Monday, 26 September 2011

DIY Atomic bomb?

A Swedish man named Richard Handl was arrested in late July for "trying to split atoms in his kitchen," as several media outlets put it. According to Handl's blog, the 31-year-old chemistry hobbyist obtained samples of radium, americium and uranium and was trying to set up a makeshift nuclear reactor on his stove.
Handl apparently didn't know that his DIY activity was illegal. He wasn't caught until he sent a question to Sweden's Radiation Authority and was answered in the form of a police visit.

Kent Hansen, professor emeritus of nuclear science and engineering at the Massachusetts Institute of Technology, thinks not. "My guess is that this is a tempest in a teapot," Hansen said, referring to the media storm surrounding Handl's arrest rather than what the Swede may have been brewing on his stovetop.
First off, Handl didn't have the right raw materials, according to Tom Ewing, a nuclear scientist at Argonne National Laboratory, outside Chicago. "As best I can tell … he only possessed minute amounts of radioactive materials: radium from old watch hands (from antique devices purchased on eBay) used in the old days to make dials 'glow' at night, americium used in trace amounts as an ionizing source in ordinary smoke detectors you buy at hardware stores, and depleted uranium (who knows where he obtained this)," Ewing said by email.

None of those were going to work. Radium doesn't fission, or split when bombarded with neutrons. To make americium work, you need a complex nuclear reactor, and depleted uranium contains scant amounts of the right variety for nuclear fission: U-235.
The vast majority of uranium in nature is another kind, U-238. "To make a reactor you have to separate out U-235 from U-238, but to do that you need something the size of centrifuges or fusion points," MIT's Hansen told Life's Little Mysteries. "These are enormous industrial facilities. There's no way someone could do it in their kitchen."

Ewing pointed out that the difficulty in enriching uranium is why so few nations have the ability to make fuel reactors. "Not a thing that you can do in your kitchen!" he wrote.
In short, Handl probably didn't have the right materials to set off a fission reaction. But what if he — or you — did? How could you get them to react?

Let's pretend you have access to pure U-235. "To make it fission, you need neutrons," Hansen said. Because your kitchen doesn't include a nuclear reactor, which uses something called a moderator to bring neutrons into contact with uranium, your only option is to pack together a critical mass of the stuff.
"You could bring together enough nuclear material to make a critical mass so that the neutrons from fission would produce more fission and sustain the reaction," Hansen said. "To do that you need a sphere of pure U-235 a foot across."

So just pack a wok full of U-235. It'll cook on its own.

There's one little problem: "If anyone had that much and tried to bring it together, they would kill themselves," Hansen said. "It will fizzle, not make an explosion, but it will produce enough radiation to kill you."

The above article is taken from Life's Little Mysteries. 

STD slides

https://docs.google.com/leaf?id=0B61FLI2_Iqx0ZjM4NmI3ZTYtYjQxMy00ODNkLThiYmUtNTY2ZWY3MjI3MjE3&hl=en_US

Wednesday, 14 September 2011

Very Important!

Here are the links to the first parts of the videos of "Black Rain White Light" and "Barefoot Gen".

Apologies for the lack of time in class to show you all the videos, but please do view all parts in your own time. You can search for the links for the rest of the video on the right side.

Black Rain White Light
http://www.youtube.com/watch?v=PqEcJZ43Tik

Barefoot Gen
http://www.youtube.com/watch?v=sCK4arVflHE&feature=related

Monday, 12 September 2011

Welcome back

To a new (and very short) semester!

This week we are starting on the Atomic bomb (no, not making it). Before you present your projects, we will be viewing the movie "Fat Man and Little Boy".

The following PDF is an article written by Richard Feynman, who is a physicist and was part of the team of the Manhattan Project.
http://calteches.library.caltech.edu/3090/1/FeynmanLosAlamos.pdf

Good luck for the project.

Monday, 5 September 2011

Something interesting on the Manhattan Project

Ever wondered what "The Mahatten Project" was about?

The following website links directly to the people involved in the project
http://intergate.cccoe.k12.ca.us/abomb/responsible.htm. Are you able to guess what the Manhattan project just by viewing this page?

Do navigate the website to gain more info - would probably help immensely in your a-bomb project!

A very big THANK YOU

Hi guys,

Thank you very much for a wonderful teacher's day in RI. It's been a great pleasure seeing your appreciation for the teachers who have taught you, and a very huge encouragement!

Special thanks to the boys who have given me presents; your gestures meant enormously to me.

Meanwhile, have a great holiday, and I am looking forward to seeing all of you already :)

Friday, 26 August 2011

Life Science Slides - GE link fixed

Central Dogma
https://docs.google.com/leaf?id=0B61FLI2_Iqx0YzZmYzgzYzQtNmU2MS00ZTk0LWFkNTYtYzAwYzVhYTQzZDY3&hl=en_US

Transcription Video


Translation Video


There are also many other good animations out there - do take a look at some of them.

The following video shows DNA replication - the next part of the Life Science topic we will be covering in the next lesson.



Genetic Engineering Slides
https://docs.google.com/leaf?id=0B61FLI2_Iqx0NjgxNDk5ODctODM0ZS00NWY1LThlYzgtMjRhMDExYzA0M2Zh&sort=name&layout=list&num=50

Wednesday, 24 August 2011

ATOMIC BOMB Project - link fixed

Hi guys,

I know you have all been waiting for this. Sorry for deseminating this only now, but don't worry, there is definitely ample time, and all factors will be taken into consideration when grading. Further details will be explained in class next week, and I will be giving you some time to come together in your groups to discuss.

https://docs.google.com/leaf?id=0B61FLI2_Iqx0ZWU4ZDRiYTEtMGRhZC00ZTdhLWFlNmUtZjkyYmE1ZTQ3YTI5&sort=name&layout=list&num=50

The other relevant learner outcomes and worksheets on atomic bomb after-effects will be given out during Term 4. If you can, go borrow and watch the movie "Fat Man and Little Boy".

Good luck for the assignment!

Wednesday, 17 August 2011

Survey on Teaching and Learning of Science

Hi all,

This last term of teaching you have been eventful, and I have learnt a lot from you boys. Now that we are coming to the end of the term, I would like to have your feedback on your science lessons so that I can understand your learning needs better, and improve on my teaching.

Please complete the survey in your own time at the following website: https://spreadsheets.google.com/spreadsheet/viewform?formkey=dGsyRVZHNDZ1UXBJYVJZemFLcjZfdkE6MQ.

The last date of completion of the survey is 31 August 2011.

Thank you very much for being my students this term - I've enjoyed my time with all of you :)

Tuesday, 16 August 2011

Monday, 15 August 2011

Dead Grandmother/Exam Syndrome

Exams are coming!
Does that mean more grandmothers are going to be "dead"?

Check out the following website on a mock paper (yes, very much like the RE paper you should be writing) that Mike Adams from the Biology Department of the Eastern State Connecticut University has written.
http://www.cis.gsu.edu/~dstraub/Courses/Grandma.htm

Thursday, 11 August 2011

Why do you need to know the baby's sex?

http://www.livescience.com/15475-blood-test-baby-sex-pregnancy.html

Blood Test Predicts Baby's Sex at 7 Weeks



Some prenatal gender tests that use mom's blood are very accurate at determining baby's sex, a new study finds. But curious parents-to-be should be wary of online marketers that claim to be able to figure out fetal gender using just a woman's urine.

New research to be published Aug. 10 in the Journal of the American Medical Association finds that after seven weeks into a pregnancy, tests that analyze mom's blood for fetal DNA can correctly identify a male fetus 95.4 percent of the time and a female fetus 98.6 percent of the time on average. In comparison, tests that analyzed DNA from urine instead of blood were only accurate 41 percent of the time, said study researcher Diana Bianchi, a reproductive geneticist at Tufts University School of Medicine.

"It was worse than flipping a coin," Bianchi told LiveScience.

Why baby's sex matters

Ultrasound imaging can sometimes reveal the sex of a baby as early as 11 weeks into pregnancy, though the results are wrong as much as 40 percent of the time. Most pregnant women in the United States get an ultrasound between 18 and 22 weeks of pregnancy that looks for fetal anomalies. At that point, the fetus' sex can be determined with high accuracy.

Some people don't like to wait that long. Chelsea Gladden, who blogs at breezymama.com, told LiveScience that she and her "swollen ankles" needed the excitement of finding out her baby's sex about halfway through the pregnancy, but said she would have found out earlier if she could have. "I was definitely consumed with finding out," Gladden said.

But curiosity isn't the only reason for earlier gender testing. Certain genetic disorders are linked to the X chromosome, so they overwhelmingly affect males, whose XY sex chromosomes mean they lack the "backup" X that women have. Families at risk for these disorders can now opt to have amniocentesis, in which the fluid that cushions the fetus in the womb is extracted and tested, or a procedure called chorionic villus sampling, both of which carry a small risk of miscarriage.

A non-invasive blood test would cut down on such testing by 50 percent because moms carrying female babies wouldn't need to worry, said Bianchi. Bianchi is on the advisory board and holds stock options in the biotechnology company Verinata Health, Inc., which has the goal of developing non-invasive fetal abnormality tests.

Another disorder, congenital adrenal hyperplasia, or CAH, disrupts hormone balance, resulting in a female fetus taking on masculine traits. Moms carrying fetuses with CAH take steroids during their pregnancies, which can have unpleasant side effects. If fetal sex were known earlier, Bianchi said, the moms carrying male fetuses with CAH would be able to skip the steroids.

Chromosome-based diagnoses of gender are also important to parents whose children are born with ambiguous genitalia. If an ultrasound reveals genitals that could be male or female, Bianchi said, knowing the baby is XX or XY can give parents a road map for what gender to raise the child.

It's a boy! (or girl)

Blood tests for fetal gender aren't available clinically in the United States, Bianchi said, though they are used in Europe for diagnosis in high-risk pregnancies. A number of companies do sell blood and urine tests of fetal sex to parents online for several hundred dollars.

Bianchi and her colleagues combed through the scientific literature to find studies on those blood and urine tests that use fetal DNA from mom's blood to identify sex. Only males have Y chromosomes, so if Y chromosomes are found in mom's blood, she's likely carrying a baby boy. If no Y chromosomes are found, she's probably expecting a daughter.

After excluding studies that lacked data or were too small, Bianchi and her team came up with 57 studies of prenatal sex tests to analyze. They found that urine tests were extremely unreliable, possibly because by the time fetal DNA is filtered from the blood into the urine, it's been broken down.

Blood tests, on the other hand, revealed fetal DNA quite early. Before seven weeks, blood tests correctly identified male fetuses only 74.5 percent of the time. After seven weeks, however, accuracy went up. Tests conducted between seven and 20 weeks of pregnancy accurately identified baby boys about 95 percent of the time and baby girls about 99 percent of the time. After 20 weeks, these test were extremely accurate, pegging boys as boys 99 percent of the time and girls as girls 99.6 percent of the time.

Parents of at-risk pregnancies should talk with their doctors, Bianchi said, because blood tests could help prevent more invasive procedures down the road. Bianchi said she sends samples to the U.K. when she really needs a test done.

But for moms and dads who just want to know what color to paint the nursery, Bianchi recommends patience.

"Currently, they would have to go to the Internet, and I would say that they should be wary," she said. "There is not a whole lot of transparency in those methods or the actual performance results."
The study was funded by the National Human Genome Research Institute.

Monday, 8 August 2011

Geneticists vs Biochemists (Part II)

This is the second installment of the story of geneticists vs biochemists! Read how the biochemist makes his witty comeback!
The Demise of Bill

by Douglas R. Kellogg

On a hill overlooking an automobile factory, lived Bill, a retired geneticist, and a retired biochemist (nobody knew his name). Having spent a life in pursuit of higher learning, both were wholly unfamiliar with how cars worked, and they decided that they would like to learn about the functioning of cars. Having different scientific backgrounds they each took a very different approach. Bill, not being inclined towards hard work (like most geneticists), immediately came up with a scheme that he thought would lead him to an understanding of cars. The next morning he went down the hill and tied the hands of one of the workers in the factory. He then went back up the hill and sat down to a cup of coffee. As he was just starting to sip his cup of coffee, he heard some banging noises and went out to the garage to see what was going on. When he looked in the garage he found that the biochemist had gotten one of the cars from the factory and was already covered with grease and oil as he was doing something under the hood. When Bill asked the biochemist what he was doing, he replied: "I'm taking the car apart to see how it works". The geneticist laughed and then sat down to enjoy his cup of coffee while he made fun of the biochemist. Bill spent the entire day drinking coffee while the biochemist struggled and sweated under the hood of the car.''

Towards the end of the day, as the exhausted biochemist was washing up, the geneticist pointed at the factory below. Cars were rolling out of the factory, and each one lacked a particular circular device (the steering wheel). Moreover, each of the cars failed to make the first turn in the road as they left the factory, and all the cars were piling up on the lawn. "Hah!" exclaimed the geneticist, "The worker whose hands I tied up today is responsible for installing the circular device, and the circular device is responsible for steering the car". The geneticist then asked the biochemist what he had learned that day. The biochemist said that he had been focusing on a small white object (the spark plug) and that he did not yet know what it did. The geneticist hooted with laughter.

The next day, the geneticist, emboldened by his success, went back down the hill and tied the hands of another worker. He then went back up the hill to get a cup of coffee. As he sat down to his coffee, he heard an explosion in the garage. He ran out to see what happened, and he found the biochemist picking himself up off the ground, his face all black and most of his hair burned away. When Bill asked in amazement what had happened, the biochemist simply replied: "I have found that the liquid in the tank of the car is fairly explosive". Later that day, when they looked down at the factory to see the effect of Bill's experiment, they observed that there were no cars coming out of the factory. Bill seemed puzzled.

This continued for many days. The geneticist gloated over his every discovery. For instance, at the end of one day the cars that rolled out of the factory were missing the front and rear windows, but not the side windows. Bill told the toiling biochemist: "The worker whose hands I tied today is responsible for installing the front and back windows, and this process is independent of installing the side windows." One evening, as they were drinking some beer and arguing, the biochemist asked Bill "Now that you have learned so much, tell me how the car works." Bill seemed puzzled by the question, but after thinking awhile he said that he had noticed that whenever the cars don't have the round things (the tires) they are completely unable to go anywhere at all. He therefore concluded that these round things were actually responsible for moving the car. The biochemist had another sip of his beer and noticed how beautiful the sunset can be after a good day of hard work.

Meanwhile, the biochemist, after many hard months of work, thought that he was beginning to define some pathways. In one pathway, he found that the explosive liquid in the tank moved through a small tube to a device that turned it into a vapor, and that the vapor was sucked into some cylindrical chambers. In another pathway, an electrical current flowed from a battery to the white devices he had studied earlier, and then formed a spark that ignited the explosive vapor, thus forcing a piston out. The biochemist had also gone down the hill and taken the time to look at the cars that failed to leave the factory when Bill had tied the hands of some of the workers. He found that they were lacking carburetors, spark plugs, drive shafts, gasoline, etc. By studying these cars, he was able to confirm some theories that he had developed regarding the functions of the cars components.

After awhile, the geneticist decided that he now knew enough about cars, and he wanted to get one so that he could go out while he waited for the results of his experiments. He decided to get a Volkswagen Camper Van. The day he got his van, he stopped by the garage to see what nonsense the biochemist was up to. The biochemist was sitting in the car pumping the clutch, and each time he did a stream of liquid shot out from underneath the car. He told Bill that he thought the liquid in the tube leading from the clutch pedal to the clutch played a critical role in disengaging the gears from the drive shaft. Bill laughed and then drove off to spend the day at a Three Stooges Film Festival that was showing at a nearby theater.

One day, several weeks later, Bill spent the day surfing and then got in his van to go home. But when he turned the key, nothing happened. He wasn't sure what was wrong, and he wondered whether or not his car might need new wheels. He tried the key several more times and then got out and started to walk. Pretty soon it started to rain. He tried to hitchhike but nobody seemed to want to pick him up, and he did not make it home until late that night. When he got home, the biochemist asked him where he had been, and Bill told him what had happened. Bill confessed that he did not know what to do, but the biochemist said that he might be able to help. The next day, they drove back to Bill's stalled van in the biochemist's car--a 1964 Valiant with a V8 engine and a push-button transmission. The geneticist couldn't help noticing how smoothly the biochemist's car ran. When they got to Bill's car, the biochemist rapidly determined that one of the battery cables no longer made a good connection, and he had the car running in no time at all. As Bill drove away, he just shook his head.

Bill's car kept breaking down, and every time it did the biochemist had to go out and fix it. He tried to teach Bill how cars work, but Bill didn't seem to understand and was always more interested in his hand-tying experiments. The story came to an end when Bill's car crashed into a tree. He had been driving along just fine when a fruit fly crawled into his eye and caused him to swerve off of the road. Unfortunately, he was not wearing his seat belts because when he had tied the hands of the worker that installed them, the cars that came out of the factory seemed to function fine, and Bill had concluded that seat belts were vestigial and not important to the functioning of the car. Remarkably, Bill survived the accident, but as soon as he got out of the hospital he got a new car and had the biochemist help him start taking it apart.


Douglas R. Kellogg is in the Department of Physiology, School of Medicine, University of California, San Francisco, CA 94143.

GENErations, Volume 2, Number 1
1994 Genetics Society of America, March 31, 1994

A new ART method?

Woman to Receive Uterus Transplant From Mom. Will It Work?

Natalie Wolchover, Life's Little Mysteries Staff Writer
14 June 2011
http://www.lifeslittlemysteries.com/woman-receive-uterus-womb-transplant-mom-will-it-work-1784/

A Swedish woman may soon become the first person ever to carry a baby in the very womb from which she was born. Sara Ottosson, a 25-year-old who, like 1 in 5,000 women, was born without a uterus, has been shortlisted for an experimental uterus transplant surgery. Sara's would-be womb donor is Eva Ottosson, her mother.

"I've had two daughters, so it's served me well," Eva Ottosson told the press, referring to her uterus. "[Sara] needs it more than me."

Sara, like all women whose wombs are missing, dysfunctional or were cancerous and had to be removed at a young age, cannot naturally conceive and give birth to a child. Like many others, Sara is so desperate to do so that she has volunteered for a completely unproven surgery — one that has never before worked in humans — in which her mother's uterus will be transplanted into her abdomen. It will then be implanted with one of Sara's own eggs, fertilized in vitro. After delivering the baby nine months later, Sara will go back under the knife to have the borrowed uterus removed.

A previous attempt at uterus transplantation was made in 2000 in Saudi Arabia, but the recipient's body rejected the foreign organ, and it had to be removed four months into her pregnancy. Now, a team led by Mats Brannstrom, a Swedish surgeon, thinks that enough research has since been done to try the procedure again. Sara hopes the team will choose her for their first attempt.

Edwin Ramirez, a gynecologist at Antelope Valley Hospital in Lancaster, Cali., who leads a group that also hopes to transplant a uterus within the next two years, told Life's Little Mysteries what makes the surgery so unique, and why a mother-daughter donor-recipient team provides the best shot for pulling it off.

Will it work?
"A uterus transplant is complex in the sense that the pelvis is more vascular than other parts of the body — it has more blood vessels — so the risk of bleeding during uterus removal is higher than with other organs," Ramirez said. He and his colleagues are developing a protocol for the organ removal procedure by operating on sheep and monkeys.

Another issue is organ rejection: When you receive an organ transplant, your immune system treats the foreign organ as an invading enemy and tries to break it down. Organ recipients must stay on a regimen of "immunosuppressive" drugs for the rest of their lives to stifle this natural response. Sometimes, though, the drugs don't work — and they didn't work for the patient involved in the previous uterus transplant attempt.

Furthermore, immunosuppressive drugs have side effects (such as weakening the immune system's response to real infections and illnesses) which could be dangerous to both mother and fetus during pregnancy. An appropriate drug regimen thus needs to be designed specifically for uterus transplantation recipients.

Despite these complications, uterus transplantation is less complex overall than heart or liver transplantation, Ramirez noted; the procedure has simply been slower to develop because it isn't life-saving. "It's a little different than your traditional organ transplantation because we're dealing with a nonvital organ. It's more of a life-improving procedure," he said.

World's best mom
The mother of the recipient makes the ideal donor, Ramirez explained. The mother of an adult daughter is most likely in her late 50s or early 60s, past menopause, and is no longer in need of her uterus. "You're performing an operation on a female that really doesn't need to have her uterus removed, but she's doing it to benefit her daughter," he said.

Old age is no issue when it comes to the uterus: It can be brought back to full functionality at any point. "The uterus will always be functioning. If you give it estrogen, it's going to respond. If you prepare the uterus, it should work perfectly fine in the recipient," Ramirez said.

Only a mother-daughter pair who share the same blood type would be considered for surgery, Ramirez explained, because this lowers the chance of organ rejection. Having 50 percent of the same genes also means the mother-daughter pair might share similarly positioned blood vessels, he said, making it easier for surgeons to lock the transplanted organ into place in the daughter.

In short, he said, "If we can transplant a uterus into the recipient who actually was born out of that uterus there's less chance of rejection."

Medical competition
Ramirez and Brannstrom are colleagues who have worked together on uterus transplantation research in the past, Ramirez said, but now they lead separate teams, both of which would like to be the first to transplant a womb.

"From a personal standpoint, I feel that I know Brannstrom fairly well and I think he's making this public because he sees that our group is advancing fast," Ramirez said. "He doesn't want to be behind in research."

Ramirez said Brannstrom may well be ready to do the surgery within a year, but that his group is nearly ready, too. "We already have our patients screened and ready to go. Do I feel like I can do it tomorrow? Yes. But I'm a perfectionist," Ramirez said.

Sunday, 7 August 2011

Can you solve the mystery on heredity?

Read on and see if you can solve this medical mystery!

Medical Mystery: Only 1 Identical Twin Has Rare Illness

05 August 2011

When the girl was 8 years old, she started to rapidly gain weight, and put on 75 pounds by the time she was 9. She was instructed to exercise, which helped stabilize her weight, but when she exerted herself, she turned blue.

Then at 9, she developed breathing problems. Doctors first thought she had asthma, then pneumonia. It wasn't until she was taken to the emergency room with extremely low oxygen levels in her blood that doctors suspected her seemingly disjoined symptoms might be related.

The girl was later diagnosed with Rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation, or ROHHAD, an extremely rare condition that has been identified in just 75 people worldwide.

But there is something that makes this girl's case even more unique: She has an identical twin. Although the pair have the same DNA, the girl's sister has so far shown no signs of the affliction. That's puzzling because researchers had suspected ROHHAD was genetic.

"[The other] twin continues to do fine, which is amazing," said Dr. Pallavi Patwari, who treated the girl at Children's Memorial Hospital in Chicago, and is one of the world's few experts on ROHHAD. "It really speaks to the fact that there's a lot of things that we need to learn about ROHHAD," Patwari said.

The twins' case, overseen by Patwari and her colleagues, provides a unique window to study ROHHAD's cause. It suggests that epigenetics, or the way our cells read our genes, may play a greater role than genes themselves, she said. Though identical twins have the same DNA sequence, their cells could read their genes differently.

"We really have to start looking more broadly than the simple DNA sequence," Patwari said.

Rare disease
Children with ROHHAD suffer an array of symptoms. The first sign is usually rapid weight gain. Other symptoms include early puberty, breathing problems and tumors in nerve tissue. The disease usually strikes between the ages of 1 and 10.

Many of the disease's features are caused by problems in the part of the brain called the hypothalamus, which is involved in regulating the body's automatic functions, such as body temperature, hunger and breathing.

The breathing problems in ROHHAD are unique, Patwari said. "It's not that they work hard to breathe or that they feel short of breath," she said. It's that the brain does not send signals to increase the breathing rate when it needs to, such as when the oxygen levels are too low.

The twin with ROHHAD later developed tumors in her nerve tissue, which were removed, and problems with her heart rate. She had a pacemaker implanted when she was 10 years old. Now 13, her condition is stable, and she requires ventilator support only at night.

The other twin also gained weight when she was a teen, but her weight gain was mild compared to that of her sister, and she did not have breathing problems.

Is it genetic?
Although only one twin developed ROHHAD, the disease could still be partly genetic, the researchers said. It could be that a mutation predisposes someone to ROHHAD, but something in the environment triggers its development.

Another idea is that the disease is set off by the body's response to cancer cells, although tumors occur in only about 40 percent of cases.

Patwari said she and colleagues hope to compare the entire genomes of the twins to gain insight into ROHHAD's cause. They also want to look for the presence of epigenetic changes that might turn certain genes on or off. However, obtaining funding for this research has been difficult.

Research on this rare disorder might also have broad applications. Patwari hopes it can provide a greater knowledge of what causes obesity.

"If we understand ROHHAD, we're hoping we'll understand a piece of what goes into the actions that cause obesity in general," Patwari said.

Thursday, 4 August 2011

Some helpful hints on how to solve pedigree problems

Some rules of thumb to determine the mode of inheritance:
Dominant traits:
Affected individuals have at least one affected offspring.
The phenotype appears every generation.
Unaffected progeny do not transmit the trait to their offspring.
Two unaffected parents have only unaffected offspring.

Recessive traits:
Unaffected parents can have affected offspring.
Affected progeny are both male and female.
May skip generations.

X-linked dominant:
Trait is never passed from father to son.
All daughters of an affected father are affected.
Male phenotype is generally more severe than female phenotype although more females are typically affected.

X-linked recessive:
Trait is never passed from father to son.
Males are more likely than females to be affected.
All affected males in a family are related through their mother.


The above is taken from http://bioserv.fiu.edu/~biolab/labs/genetics/karyotyping%20and%20web%20problems.htm.

Wednesday, 3 August 2011

Geneticists vs Biochemists

The following is a story of a geneticist and biochemist. It has been an unspoken characteristics of aspects of biochemistry research and work to be much more tedious and difficult than genetics. This story hints at these characteristics of genetics and biochemistry research.

However, there is a second installment of this story, where a comeback is made by a biochemist to defend his work. Keep a lookout on the second installment!



The Salvation of Doug

by William T. Sullivan

On a hill overlooking an automobile factory, lived Doug, a retired biochemist, and a retired geneticist (nobody knew his name). Every morning, over a cup of coffee, and every afternoon, over a beer, they would discuss and argue over many issues and philosophical points. During their morning conversations, they would watch the employees entering the factory below to begin their work day. Some would be dressed in work clothes carrying a lunch pail, others, dressed in suits, would be carrying briefcases. Every afternoon, as they waited for the head on their beers to settle, they would see fully built automobiles being driven out of the other side of the factory.

Having spent a life in pursuit of higher learning, both were wholly unfamiliar with how cars worked. They decided that they would like to learn about the functioning of cars and having different scientific backgrounds they each took a very different approach. Doug immediately obtained 100 cars (he is a rich man, typical of most biochemists) and ground them up. He found that cars, consist of the following: 10% glass, 25% plastic, 60% steel, and 5% other materials that he could not easily identify. He felt satisfied that he had learned of the types and proportions of material that made up each car. His next task was to mix these fractions to see if he could reproduce some aspect of the automobile's function. As you can imagine, this proved daunting. Doug put in long hard hours between his morning coffee and afternoon beer.

The geneticist, not being inclined toward hard work (as is true for most geneticists) pursued a less strenuous (and less expensive) approach. One day, before his morning coffee, he hiked down the hill, selected a worker at random, and tied his hands. After coffee, while the biochemist zipped up his blue jump suit, adjusted his welders goggles, and lit his blow torch to begin another day of grinding, the geneticist pueered around the house, made himself another pot of coffee, and browsed through the latest issue of Genetics.

That afternoon, while the automobiles were rolling off the assembly line, Doug, wet with the sweat of his day's exertions, took a sip of beer and as soon as he caught his breath began discussing his progress. "I have been focusing my efforts on a component I consistently find in the plastic fraction. It looks like this (he draws the shape of a steering wheel on the edge of a napkin). Presently I have been mixing it with the glass fraction to see if it has any activity.. I am hoping that with the right mixture I may get motion, although I have not had any success so far. I believe with a bigger blow torch, perhaps even a flame thrower, I will get better results."

The geneticist was only half listening because his attention was drawn to the cars rolling off the assembly line. He noticed that they were missing the front and rear windows, but not the side windows. As soon as the biochemist finished speaking (geneticists are very polite conversationalists), the geneticist proclaimed, "I have learned two facts today. The worker whose hands I tied this morning is responsible for installing car windows and the installation of the side windows is a separate process from the installation of the front and back windows."

The following day the geneticist tied the hands of another worker. That afternoon he noticed that the cars were being produced without the plastic devices the biochemist was working on (steering wheels). In addition, he noticed that as the cars were being driven off to the parking lot, none of them make the first turn in the road and they begin piling up on the lawn. That evening, to Doug's dismay, the geneticist concluded that steering wheels were responsible for turning the car and, in addition, that he had identified the worker responsible for installing the steering wheels.

Emboldened by his successes, the next morning the geneticist tied of the hands of an individual dressed in a suit and carrying a briefcase in one hand and a laser pointer in the other (he was a vice president). That evening the geneticist, and Doug (although he would not openly admit it), anxiously awaited to see the effect on the cars. They speculated that the effect might be so great as to prevent the production of the cars entirely. To their surprise, however, that afternoon the cars rolled off the assembly line with no discemible effect.

The two scientists conversed late into the evening about the implications of this result. The geneticist, always having had a dislike for men in suits, concluded that the vice president sat around drinking coffee all day (much like geneticists) and had no role in the production of the automobiles. Doug, however, held the view that there was more than one vice president so that if one was unable to perform, others could take over his duties.

The next morning Doug watched as the geneticist, in an attempt to resolve this issue, headed off towards the factory carrying a large rope to tie the hands of all the men in suits. Doug, after a slight hesitation, abandoned his goggles and blow torch, and stumbled down the hill to join him.



Reproduced from the Genetics Society of America Newsletter, April 30 1993. GENErations Vol. 1, No. 3

The author, William Sullivan, is a Professor in the Department of Biology, Sinsheimer Labs, University of California at Santa Cruz, Santa Cruz, CA 95064. He uses this story to explain the rationale behind mutational analysis in his introductory genetics classes, and suggests that it may be useful for teaching students the basic differences between genetics and biochemistry.

ART lesson slides

Hi babies (pun fully intended),

Here are the lesson slides and summary table for ART.

Abortion
https://www.opendrive.com/files?34957172_9duGM

ART
https://www.opendrive.com/files?34957161_yRkHO

ART summary


Study hard!

Monday, 1 August 2011

New sexual reproduction method!

Remember when you were told to create an imaginary animal with an entirely novel sexual reproductive method in your groups?


Now here's a REAL insect, with a very interesting and novel way of reproduction which scientist have only recently discovered!

Strange Insect Incest May Spell the End for Males by Remy Melina


Scientists recently discovered that the cottony cushion scale insect isn’t a hermaphrodite — the species' females fertilize their own eggs through infectious, parasitic tissue that infects them at birth and is derived from the leftover sperm of their fathers.

For the full article, please visit

http://www.livescience.com/15292-insect-incest-male-reproduction.html


Natural selection is NOT the survival of the fittest!

Remember the misconception that Natural Selection is based on the principle of the survival of the fittest?

So what is it exactly that drives evolution?

The following article is retrieved 31 July 2011 from http://www.livescience.com/1736-greatest-mysteries-drives-evolution.html

by Jeanna Bryner

Boobies were a species of bird that Charles Darwin found on the Galapagos Islands.

From bizarre butterfly spots to rainbow-colored lizards to adaptations that allow squirrels and even snakes to "fly," physical innovations in the natural world can be mind-boggling.

Natural selection is accepted by scientists as the main engine driving the array of organisms and their complex features. But is evolution via natural selection the only explanation for complex organisms?

"I think one of the greatest mysteries in biology at the moment is whether natural selection is the only process capable of generating organismal complexity," said Massimo Pigliucci of the Department of Ecology and Evolution at Stony Brook University in New York, "or whether there are other properties of matter that also come into play. I suspect the latter will turn out to be true."

Flexible genes

Some scientists are proposing additions to the list of evolutionary forces.

"Over the past decade or two, scientists have begun to suspect that there are other properties of complex systems (such as living organisms) that may help, together with natural selection, explain how things such as eyes, bacterial flagella, wings and turtle shells evolve," Pigliucci told LiveScience.

One idea is that organisms are equipped with the flexibility to change their physical or other features during development to accommodate environmental changes, a phenomenon called phenotypic plasticity.

The change typically doesn't show up in the genes. For instance, in social bees, both the workers and guards have the same genomes but different genes get activated to give them distinct behaviors and appearances. Environmental factors, such as temperature and embryonic diet, prompt genetic activity that ends up casting one bee a worker and the other a guard.

If beneficial, this flexibility could be passed on to offspring and so can lead to the evolution of new features in a species. "This plasticity is heritable, and natural selection can favor different kinds of plasticity, depending on the range of environmental conditions the organism encounters," Pigliucci said.

Made to order

Self-organization is another evolutionary force that some experts say whips up complex features or behaviors spontaneously in living and non-living matter, and these traits are passed on to offspring through the generations.

"A classic example outside of biology are hurricanes: These are not random air movements at all, but highly organized atmospheric structures that arise spontaneously given the appropriate environmental conditions," Pigliucci said. "There is increasing evidence that living organisms generate some of their complexity during development in an analogous manner."

A biological illustration of self-organization is protein-folding. A lengthy necklace of amino acids bends, twists and folds into a three-dimensional protein, whose shape determines the protein's function. A protein made up of just 100 amino acids could take on an endless number (billions upon billions) of shapes. While this shape-shifting takes on the order of seconds to minutes in nature, the fastest computers don't have the muscle yet to pull off the feat.

The mechanism that triggers the final form could be a chemical signal, for instance.

Novelties in nature

The environment also could drive changes in an animal's appearance or phenotype, a phenomenon that intrigues many biologists.

For instance, Sean Carroll, a molecular biologist at the University of Wisconsin-Madison, discovered butterflies in East Africa have different colorings depending on when they hatch. Those hatching during the wet season emerge with brightly colored eyespots while their dry-season relatives wear neutral cryptic coats.
Biology has a pretty good understanding of how animals develop from a fertilized egg to a fully formed organism.

"We just don't understand how … the environment and [the] genetic blueprint interact during development," said Theunis Piersma of the Center for Ecological and Evolutionary Studies at the University of Groningen in the Netherlands.

Piersma's research on shorebirds called red knots has revealed the birds can morph their phenotypes depending on their migration routes.

When brought into captivity and placed in colder temperature environments, the shorebirds' flight muscles and organs shrink to reduce heat loss. The birds pass on to offspring the capacity to make these changes.

So the mystery is starting to clear around how diverse species with an array of features evolve. The field, which had relied in the past mostly on fossil records, got a boost with the development of genetic techniques and the integration of diverse sectors of science, connecting genetics, biology, ecology and computer science.

While scientists are shedding light on natural mechanisms that work to shape species, many questions in the field are brewing on the lab-bench. And the original question examined by Charles Darwin—what is the mechanism that causes new species to evolve—has yet to be fully explained. And another related question looms: How important are chance events, as opposed to natural selection, to shaping organisms?

Aspiring parents, genotypes and phenotypes: the unexamined myth of the perfect baby

by Andrea D. Gurmankin, Peter A. Ubel, Elizabeth Banger, Glenn McGee

Abstract
Although many have argued that assisted reproductive technologies ("ARTs") attract those with a desire to genetically engineer their offspring, this claim has yet to be verified. To address this question, we surveyed three groups: the general public, people enrolling in an in vitro fertilization ("IVF") program, and pregnant couples. We asked subjects which traits they would select in their children if it were possible to use a magic wand to do so and to value genetic relatedness. In our sample, the potential parents who were using ARTs were less likely to express a desire to select traits in their offspring than were the general public, and just as likely as the pregnant couples. Those using ARTs, however, placed greater importance on having genetically related children than the others. Thus, the widely held view that reproductive technology is utilized by those most likely to favor genetic engineering is falsified by our findings.

For the full article please visit http://findarticles.com/p/articles/mi_hb3243/is_4_68/ai_n29199446/

By the way, this is an EXCELLENT reference article on how to write your scientific articles (e.g. RE report).

Wednesday, 27 July 2011

Mission (Im)possible?

In today's lesson on Heredity - Phenotypic Variations, you saw how each of us differ in various traits and charcteristics.

Here's a mission for you all:

There is ONE male teacher who sits in Staff Room 1, who has a COUNTER-CLOCKWISE hair whorl!

Can you find out who he is? =)

Clue: He is a science teacher.

Wednesday, 20 July 2011

Would You Consider Abortion in These Situations?

Disclaimer: The following is taken from various Internet sources, and contains religious inclinations. It does not aim to impose any religious ideologies.

A man raped a 13 year old black girl and she got pregnant. If you were her parents, would you consider recommending abortion? 

There is a preacher and wife who are very, very poor. They already have 14 kids. Now she finds out she is pregnant with her 15th. They are living in tremendous poverty. Considering their poverty and the excessive world population, would you consider recommending abortion? 

The father is sick with sniffles, the mother has TB. They have 4 children. The first is blind, the second is dead. The third is deaf and the fourth has TB. The mother finds she is pregnant again. Given the extreme situation, would you consider recommending abortion?

A teenage girl is pregnant. She is not married. Her fiancée is not the father of the baby, and he is very upset. Would you recommend an abortion?


If you have answered “yes” to any of these situations:

In the first case you would have killed John Wesley, one of the great evangelists of the 19th century.

In the second case, you would have killed Beethoven.

In the third case you would have killed Ethel Waters, the great black gospel singer.

In the fourth case you would have recommended the murder of Jesus Christ.

Tuesday, 19 July 2011

2.3 Reflections on ART


In today's lesson, you have learnt about the various forms of ART, and how to identify the most appropriate ART for certain infertility issues. You also had a discussion on ethical issues surrounding surrogacy and the rights of a child conceived via ART.

Now, reflect individually on the following questions as a guideline, while incorporating Elements of Thought. Submit a min 100-word reflection by Friday 11:59pm through e-mail. You may wish to include any other points in your reflections.


Information: 3 things I have learnt about Assisted Reproductive Techniques – differences, affordances, advances, etc.
Implications/Perspectives: 2 impacts of such advances in human reproduction on families and society
Consequences: 1 way to reconcile adverse human emotions towards such medical advances

2.2 Assisted Reproductive Techniques

For the upcoming lesson on Assisted Reproductive Techniques, please visit http://www.nytimes.com/2010/10/05/health/research/05nobel.html
http://www.artificialinsemination.net/
http://www.moh.gov.sg/mohcorp/mediaforums.aspx?id=4632.
to learn more about assisted reproductive techniques.

You will need information gathered from these two sites to complete ExB6 as well as the interesting tasks in the next class!

Sunday, 17 July 2011

AND finally, the newest update on AIDS

Drugs Can Avert HIV Infection

http://news.discovery.com/human/hiv-infection-prevention-110713.html

Rose Palazzo
July 14, 2011

For the first time, studies show that AIDS drugs taken daily can cut "by more than half a person’s chance of becoming infected with HIV through heterosexual intercourse," according to the Washington Post.

"This is a good day for HIV prevention," Dr. Lynn Paxton, HIV research coordinator for the Centers for Disease Control and Prevention, said to the Associated Press about the promising new findings.

The first of the new studies, run by the Centers for Disease Control, involved more than 1,200 men and women in Botswana. About half received Truvada, an HIV treatment made by Gilead Sciences Inc. The other half received a fake pill.

An analysis found four of those on Truvada became infected with HIV, compared to 19 on the dummy pill. That means the real drug lowered the risk of infection by roughly 78 percent, researchers said.

The second study was funded by the Bill & Melinda Gates Foundation and run by the University of Washington. It involved more than 4,700 heterosexual couples in Kenya and Uganda. One partner had HIV and the other did not. The uninfected were given either daily placebos, Truvada pills, or another Gilead treatment, Viread.

The study found 13 HIV infections among those on Truvada, 18 in those on Viread, and 47 of those on dummy pills, according to the AP. So the medications reduced the risk of HIV infection by 62 percent to 73 percent, the researchers said.

Another report announced last year was not as promising.  The study of Truvada involved gay men in Peru, Ecuador, Brazil, South Africa, Thailand and the United States. The drug lowered the chances of infection by 44 percent, and by 73 percent or more among men who took their pills most faithfully.

It was thought to be a huge triumph. But then in April, an interim analysis of the study of 3,900 women in Kenya, Tanzania and South Africa did not show a benefit.


"Scientists are still piecing together why that study pointed to failure and the two latest indicate success. One theory is that the women in the earlier study did not take the medication as often as they should have, Paxton said," the AP reported.

Gonorrhea - its a BACTERIAL infection!

For those of you who missed out on this important information...
Drug-Resistant Gonorrhea Strain Emerges

 

July 12, 2011 1:32:00 AM


For the first time, international researchers have identified a strain of gonorrhea that is resistant to treatment with antibiotics, scientists announced at a sex disease research conference Monday.

The common bacterial infection, often called the "clap," has until now been easily treatable with antibiotics but if left alone can cause infertility in women and painful urination and a pus-oozing infection in men.

"This is both an alarming and a predictable discovery," said Magnus Unemo of the Swedish Reference Laboratory for Pathogenic Neisseria. "Since antibiotics became the standard treatment for gonorrhea in the 1940s, this bacterium has shown a remarkable capacity to develop resistance mechanisms to all drugs introduced to control it."

Details of the discovery were to be released by Unemo and colleagues at the 19th conference of the International Society for Sexually Transmitted Disease Research, on from July 10-13 in Quebec City, Canada.

Since the finding is so new, scientists are unclear how widespread the resistant strain may be in the world population, but concerns are mounting that it could spread quickly. "While it is still too early to assess if this new strain has become widespread, the history of newly emergent resistance in the bacterium suggests that it may spread rapidly unless new drugs and effective treatment programs are developed," Unemo said.

As many as 700,000 people in the United States are believed to get gonorrhea annually, according to the Centers for Disease Control and Prevention. Up to half of infected women experience no symptoms, while men usually see signs of infection within two to 30 days.

"Anyone who has any type of sex can catch gonorrhea," according to the US National Institutes of Health, which notes however that risks are higher among people with multiple partners and people who have unprotected sex. "Gonorrhea is more common in large cities, inner-city areas, populations with lower overall levels of education and people with lower socioeconomic status," added the NIH.

People who suspect they may be infected should see a doctor in order to obtain a prescription and should not attempt to treat the problem themselves, experts say.
The current treatment recommended by the CDC is an single dose pill of an antibiotic called cefixime, or a single dose of azithromycin (Zithromax) for people who are allergic to penicillin, ceftriaxone or cefixime.

Penicillin is no longer considered the standard treatment because it was previously found to be ineffective in some cases.

Tuesday, 12 July 2011

1.7 The birds and the bees

It is an expression often used in reference to teaching someone about sex and pregnancy. In the olden times, the birds and the bees is a metaphorical story used to explain the mechanics and good consequences of sexual intercourse by referring to commonly seen natural events. For instance, the idea of bees carrying and depositing pollen into flowers explains male fertilisation, and that of birds laying eggs explaid female ovulation.

But, the mechanics of courtship and sexual intercourse of the birds and the bees can be very, very different from that of humans. Do you know how they attract partners and mate?

Frigate Birds

Compared to the mating rituals and accesories of peacocks, the frigatebirds are so much more awe-inspiring! A male frigatebird inflates his red throat sac into a giant heart-shaped balloon. This takes an immense effort, and 20 minutes. He then does a courtship dance by waggling his head from side to side, spreading and shaking his wings, and calls the females to take a good look at him.

A female frigatebird then makes her choice after the viewing, and usually the male with the biggest and shiniest balloon wins. During sexual intercourse, the male bird may even possessively put his wings over her eyes to ensure that she does not get to see other males with grander balloons!


Honey bees



A female bee is selected to be bred in a designated compartment in the bee hive. She is then fed a special diet of royal jelly by worker bees to induce maturation of her sexual characteristics.

This queen bee will proceed to go on a mating flight with about 15 - 20 male bees, otherwise called drones, picked out from tens of thousands eligible bachelors in the colony. However, this is a "kamikaze" mission, because during mating, their genitals explodes and the penis snaps off inside the queen!

This bizzare phenomenon is actually a "for the sake of honey bee-kind" philantropic act. The penis left inside the queen acts as a plug to prevent other drones from fertilizing her.

Watch the mating of honey bees here.

Monday, 11 July 2011

1.6 Advocating abstinence or contraception?

New campaign targets teens, promotes responsible sexBy Hoe Yeen Nie, Channel NewsAsia | Posted: 07 October 2007 0011 hrs

SINGAPORE: The number of teenagers contracting sexually-transmitted diseases has doubled in the past five years.

Teen abortions have also not gone down. The worrying situation is despite sexuality campaigns that encourage teens to say 'no' to sex. So some are calling for a change.

One group is advocating the message that if you're saying 'yes' to sex, do it responsibly. Bayer Healthcare and web portal Youth.SG say telling teenagers to abstain from sex is no longer realistic. They believe that what is needed now is to teach youth about responsible sex.

And that means, keeping the message of saying 'no' but at the same time, promoting the use of condoms and oral contraceptives. They hope to promote this message with the help of mascots.

But some feel that there is no side-stepping the issue, even when sex is still largely seen as a sensitive topic in Singapore. Associate Professor P C Wong, chief of Obstetrics and Gynaecology Department at the National University Hospital, said: "The statistics speak for themselves. Every year, as I said, 1,300 to 1,500 teenage abortions occur. The numbers have not dropped. And STDs (sexually-transmitted diseases) have gone up, more than double. So we have to sit up and pay attention to the statistics."

"The statistics are giving us a signal, that there's a lot of teenage sexuality out there, and we have to teach our teenagers to be sexually responsible," he added. Latest figures from the Ministry of Health put the number of teen abortions in 2005 at 1,279. And in 2005, 678 teens aged between 10 and 19 years sought help for sexually-transmitted diseases, compared to 256 in 2001.

Also, a recent survey showed that four in 10 sexually active women did not use any form of contraception. This is according to the Whisper Study, which was conducted between September 2003 and December 2004.

In a statement to Channel NewsAsia, the Singapore Planned Parenthood Association said it supports the campaign to encourage teens to be sexually responsible. It said this will promote comprehensive understanding of sexuality and reproductive health. It added that it will help the people identify their own values and make decisions.

But SPPA stressed that it does not discourage abstinence. Parents Channel NewsAsia spoke to, would rather teens say a complete 'no' to sex. "Even though they are taught to use condoms or whatever, it's better not to do it," said a Muslim woman.

"Contraceptives? At this age, if you ask them to use contraceptives, that means you're encouraging them (to have sex) by using condoms and contraceptives," said a Chinese woman.

Opening up a Pandora's box? This is what Bayer Healthcare and Youth.SG hope to achieve with their latest campaign. They hope the campaign will start a discussion on issues related to teenage pregnancies and sexually-transmitted diseases. They are working with the Republic Polytechnic to expand the programme.