What Causes Us To Age?

It appears that the key to understanding aging is to look at it from a genetic perspective. At the end of all chromosomes are stretches of protein called telomeres. These telomeres protect the chromosome but every time the chromosome replicates (like in cell division), the telemeres shorten until the cell can no longer divide.

These shortened telomeres also appear to be the cause of some cancers. Studies have found shortened telomeres in pancreatic, bone, prostate, bladder, lung, kidney, and head and neck cancer.

Research looks promising in using an enzyme, telomerase,in allowing cells to divide beyond their usual life span.

Source:http://learn.genetics.utah.edu/content/begin/traits/telomeres/

Do Triplets Have the Same DNA?

Multiple births are very interesting. Triplets, if they come from the same egg that divides after fertilization, all have identical DNA. Identical triplets are very rare.

There are two other ways that triplets can occur. Non-identical triplets occur when three eggs are produced and each is fertilized separately, these triplets do not have the same DNA. The second way is for one egg to be fertilized and then divides creating two identical twins with the same DNA and then a second egg is fertilized. In this last example, two babies have the same DNA and third one is close but not identical.

What is it in food that makes me like some things and hate others?

Lots of things can cause someone to love one food and hate another. It could be the texture of the food, the smell or look of the food, or a cultural preference for a food because it reminds you of family traditions.
Scientists have found that people have a preference for creamy sensations as well as for foods that start off solid and melt in the mouth such as ice cream and chocolate.

Another factor in food preferences: People vary—probably based on genetics—in their ability to detect other textures, such as fat, and bitter and sweet tastes. Valerie Duffy, a registered dietitian and professor in the department of allied health science at the University of Connecticut, Storrs, Conn., has shown in her research that adults with a gene that makes bitter tastes more intense consume fewer vegetables containing bitter compounds, such as kale or spinach.

So you can see that taste preferences are really a very complex topic and you would be hard pressed to find a friend who had exactly the same favorite food as you do.

Source: Wall Street Journal 11/8/10

Do Genes Even Control Sleep?

It appears that genes do play a role in how long you sleep.

Geneticists studying sleep duration in people scanned the DNA of more than 4,200 Europeans, looking for genes associated with a person’s average nightly sleep time. The team found that people who have one version of a gene called SUR2 sleep about 28 minutes longer than people who have another version of the gene, said Karla Allebrandt of the University of Munich, who presented the research November 5 at the annual meeting of the American Society of Human Genetics.

Last year researchers from the University of California, San Francisco reported that a rare variation in DEC2, a gene involved in regulating the body’s daily rhythms, is associated with sleeping almost two hours a night less than average.

Source: Science News 9/12/10, p. 11.

What are genetic tests used for?

Doctors rely on genetic testing in many conditions, most of them involving pregnant women or infants. However, they may also be used in adults to see if they carry a risk factor for a disease before the symptoms even begin to show up. Doctors use genetic tests for several reasons. These include:

•Finding possible genetic diseases in unborn babies
•Finding out if people carry a gene for a disease and might pass it on to their children
•Screening embryos for disease
•Testing for genetic diseases in adults before they cause symptoms
•Confirming a diagnosis in a person who has disease symptoms

People have many different reasons for being tested or not being tested. For many, it is important to know whether a disease can be prevented or treated if a gene alteration is found. In some cases, there is no treatment. But test results might help a person make life decisions, such as career choice, family planning or insurance coverage.

How do you feel about genetic testing?






Source: http://www.nlm.nih.gov/medlineplus/genetictesting.html

What type of traits are polygenic?

Polygenic traits are traits that are controlled by several different genes. Usually these traits exist on a continuum of expression. For example consider height; there are not just two types of height but instead normal height exists on a fairly large continum of about 12 inches. Where you fall in this height range is caused by genetic material on several different genes. Other examples of the influence of multiple genese can be seen in skin color, autism, hypertension, hair color and eye color.

Can you give a few examples of incomplete dominance and codominance?

First let's start with a few definitions.
With incomplete dominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype that is a blending of the parental traits. With codominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear together.

Here are a couple of examples: Incomplete dominance is seen in wavy hair. It is a new phenotype that occurs when one parent has straight hair and one parent has curly hair. An example of condominance is found in blood types. The blood type AB is made up of both A proteins and B proteins.

How Can DNA Be Programmed?

Genes contained DNA can be turned off and on through several methods. One of the most promising ways of altering genes is through epigenetics. Many studies have indicated that the environment plays a role in activating or silencing certain genes. Most of the changes attributed to epigenetics only last for one generation meaning they may not be passed on to offspring.

Epigenetics has been offered as one possible process affecting obesity. An environment of high fat/fast foods may turn on a gene promoting weight gain while in another eating environment, this gene would be silenced.