Posted by Kristal Louie on Mon, Feb 01, 2010 @ 02:00 PM
Blog 2: What's a gene?
If DNA is the genetic material, then what are genes? To understand this, we need to go back to the 1850's to the father of genetics, Gregor Mendel and his experiments studying traits in pea plants. In analyzing his data, he suggested factors exist that pass traits from parents to offspring, and called those factors genes. When DNA was discovered years later, many scientists quickly made the association that Mendel's factors, or genes, were composed chemically of DNA molecules.
Still not clear? Let's start with the textbook definition of a gene: A hereditary unit consisting of a sequence of DNA that occupies a specific location on a chromosome and determines a particular characteristic in an organism. Put more simply, a gene is just the stretch of DNA that when read by the cell, is the code for a specific trait or cellular function. More specifically, genes specify the sequence of amino acids within proteins, which then work with numerous other proteins to generate the trait or function. Eye color is a good way to explain this. There really isn't a blue-eye gene. Rather, there is a collection of genes that encode a collection of unique proteins, that when present together in the eye, produce a blue color.
A gene is made up of combinations of the four nucleotides (A, G, C and T) in a long sequence. These unique combinations determine the gene's function, much like letters join together to form words. This information is read using the genetic code, which specifies the sequence of the amino acids within proteins. DNA is copied into the related nucleic acid mRNA, in a process called transcription, as one step to making a protein. Humans have approximately 23,000 genes person encoded by billions of base pairs of DNA.
Genes are aligned precisely all along the length of 23 pairs of much larger structures: the chromosomes. One chromosome in each pair comes from the mother and the other one from the father. The chromosomes in any particular pair look like each other, except in a boy. There is one pair of chromosomes (the sex chromosomes), which usually settles the sex of the individual. In females, the sex chromosomes are both X-chromosomes. In males, the sex chromosomes are a mismatched pair consisting of one X-chromosome and one Y-chromosome. The Y-chromosome is transmitted only by the father.
Did you know? In 2001, the DNA sequence for humans, called the human genome, was completed. This scientific accomplishment represented the largest biomedical research project of the 20th Century. Interestingly, there were actually two competing human genome projects - one financed by the US government through the NIH and one financed by a private company, Celera Genomics. There was a bitter rivalry between NIH and Celera which was finally settled by President Clinton when he, at the White House, ceremoniously declared both groups "the winner". Nonetheless, most scientists believe that the competition between the two groups greatly enhanced and accelerated the project and led to its completion years sooner than anticipated. Celera had hoped to build a commercial enterprise around their version of the genome, but was unable to build any significant business due to the availability of the public sequence. In 2004, Celera made their sequence available, without charge, to all scientists world-wide, bringing an end to what had become known as the Genome War. For a great history of the project and to access the human genome reference sequence, visit the Department of Energy's Human Genome Project site.
Dennis Gilbert
www.sbgenetics.org
support@sbgenetics.org
Posted by Kristal Louie on Fri, Jan 22, 2010 @ 03:04 PM
Blog 1: It's in my DNA
We've heard from many of our study participants that spending some blog time on a "refresher" in genetics would be welcome. Some mothers in the SB Genetics Research Project have realized that much of what they once learned in Biology class has been long forgotten. To help jog your memory, we are starting a series of blogs simply called "Genetics 101" - not the most creative, but it get's the point across. Before I start, let me introduce myself. My name is Dennis Gilbert; I have a Ph.D. in Genetics from Johns Hopkins University and am one of the Principal Investigators for the SBGenetics Research Project.
Most simply, genetics is the science of heredity and variation. Studying genetics allows us to better understand the way in which similar characteristics among family members are maintained, and why differences between individuals occur. Geneticists examine a wide variety of inherited traits in a wide range of organisms, from fruit production in trees to metabolic diseases in humans. People who study genetics do so in a wide variety of situations, from research laboratories (like the SB Genetics Research Project) to pharmaceutical companies to crop fields. Being a geneticist nowadays is extremely exciting and rewarding as new breakthroughs that really make a difference in people's lives are consistently being made.
It's in my DNA! We've heard this expression a lot and probably have used it ourselves a few times. But, what is DNA?
DNA, or deoxyribonucleic acid, is a nucleic acid - a chemical compound that contains the genetic instructions for the development and functioning of all living organisms. The main role of DNA molecules is to ensure the long-term storage of our genetic information. DNA is often compared to a set of blueprints or a recipe, or a code, since it contains the instructions needed to construct other components of cells, such as RNA and protein molecules. DNA is found in almost every cell within the human body - from the white cells in your blood to the cheek cells in your mouth. Once the sequence of your DNA has been determined, as a combination of half the DNA of each of your parents, it does not change over your lifetime.
Chemically, DNA consists of two long chains of simple units called nucleotides, named for one of four types of molecules called bases. The four bases found in DNA are adenine (abbreviated A), cytosine (C), guanine (G) and thymine (T). It is the sequence, or order, of these four bases along the DNA chain that encodes your genetic information. There are approximately 3 billion bases in each of our cell that make up "my DNA". For illustrations and more details, the National Genome Research Institute has an excellent fact sheet.
Did you know? For many years after the discovery of DNA, most scientists remained convinced that proteins, not DNA, were the carriers of our genetic information. Why? It boiled down to the numbers. It was known that proteins were made of 20 different amino acids whereas DNA was made of only four different nucleotides. Thus, it makes some sense, then, that proteins could code for MUCH greater variety with their 20 amino acids than DNA could with its four nucleotide sequence. And the code for the complete set of instructions for human life would need enormous complexity and variety. As I'll discuss in a later blog, this great variety comes from how the code is read and then used by our body to transmit the genetic instructions. In 1952, Alfred Hershey and Martha Chase conducted what are now called the "blender experiments" to prove that DNA was indeed the genetic material and put the controversy finally to rest.
www.sbgenetics.org
support@sbgenetics.org
Posted by Kristal Louie on Fri, Nov 06, 2009 @ 12:36 AM
Hello !
We are among the first researchers to study the unique theory that tiny changes to our folic acid genes might impact us in a significant way by increasing the risk of having a child with Spina Bifida. Our hope is that with the help of all the participants we will find a way to prevent Spina Bifida.
Our group includes researchers from Children's Hospital of Oakland, the University of California Berkley, Stanford University, and the University of California San Francisco. The preliminary research has shown that some of us may not metabolize folic acid as efficiently as others. That means that the standard recommendation of 0.4 milligrams may not be enough. Some of us may need to take at least 4 milligrams (a ten-fold increase from the RDA) to compensate. The unfortunate thing is that currently there are no pre-conception tests to determine if you or I might be one of these women. With the help of mothers and children with Spina Bifida we hope to find a way to provide women with this information before they become pregnant, when they can do something about it.
We want to thank all the mothers and children who have already participated. We would love it if we could get even more mothers and their children to participate as the more data we have, the stronger our results will be. So if you have already participated a BIG THANK YOU !!! If you have not, please consider participating. Help us by telling your friends about the study or send them a link to the website. We need your help!
Kristal
P.S. Please feel free to post any comments you have !
http://www.sbgenetics.org/
support@sbgenetics.org
www.sbgenetics.org
support@sbgenetics.org