-A curious adult from SingaporeAugust 20, 2004
Most theories say Native American Indians migrated to the American continent from Asia across a land bridge around 11,500 years ago. Yes, this would, in fact, make the first Americans Asians.
-A curious adult from MississippiAugust 19, 2004
It is common to look more like one parent than the other, but that doesn't mean you only get genes from that parent. You actually get your genes from both parents. We inherit half of our genes from our mother, and the other half from our dad, so that we end up with two copies of every gene*.
-A curious adult from CaliforniaAugust 6, 2004
What a fun question! This sort of thing has been bothering me too lately. The usual statistic is that all people are 99.9% the same. But is that true for men and women?
And what about our similarity to other animals? We are really only about 80% the same as a mouse at the genetic level so men and women are clearly more similar to each other than to mice. But what about chimpanzees? If people really are 98.7% the same as a chimpanzee, are male chimpanzees closer genetically to men than men are to women?
-A curious adult from ItalyOctober 25, 2007
No it isn't possible yet to check all of your genes for prevention purposes. It would be way too expensive and we just don't yet know enough about our DNA to make sense of it all anyway.
This might seem weird what with the sequencing of the human genome and all. You'd think that because we know all 3 billion letters of human DNA we would be able to look at someone's DNA and figure out what is going on. You'd be wrong.
-A curious adult from OregonAugust 17, 2004
Man, I thought the eye questions were tough! There is very little known about hair color inheritance but there are some interesting theories. I am happy to share what I've gleaned from the web. It makes sense to me but I can't necessarily vouch for it.
What is pretty well known is where hair color comes from. Hair color happens because of a kind of pigment called melanin. There are two kinds of melanin, eumelanin and phomelanin.
I think it is definitely important that we make the public aware of this risk. But there probably doesn't need to be a genetic test. The people who blush when they drink alcohol know who they are.
What they might not know about is their higher risk for esophageal cancer. Or that there is no increased risk if they don't drink any alcohol.
The DNA difference that causes them to blush is only a problem when they drink. No alcohol means no increased risk of esophageal cancer.
The alcohol breakdown process is controlled by a few different genes. Some genes have the instructions for breaking alcohol down into acetaldehyde. Another set of genes controls turning acetaldehyde into acetic acid.
ALDH2 is one of the genes in charge of turning acetaldehyde into acetic acid. Some people have a small variation in that gene so that it barely works. Scientists call this version ALDH2*.
-A graduate student from TexasAugust 5, 2004
From what I've read, colobomas can be passed down through the generations but not always. When a coloboma is referred to as congenital, it means that it was present at birth; it does not mean that it is necessarily genetic. While what they are is pretty well understood, where colobomas come from is not.
My first inclination was to answer no but then I got to thinking...
The reason my gut reaction answer was no is because there was a big debate early on in genetics about traits and how they are passed on.
One school thought that things we do and things done to us can be passed on. The other school argued that it is all about selecting the most fit individuals in a population who then pass their traits on.
No amount of surgery, hormone injections or anything else will change someone's DNA from a man's to a woman's (or vice versa).
As you know, for humans, sex is determined by the presence of a Y chromosome -- humans with an X and a Y chromosome are male and those with two X chromosomes are female. No current (or probably future) technology can replace a chromosome in all of our trillions of cells.
A micro-satellite* is a small sequence of DNA that is repeated many times. The size of the repeated sequence is usually between 1 and 4 base pairs. When the number of repeats varies between people, a micro-satellite is called polymorphic.
Micro-satellites are usually located in DNA outside of genes and are found in all sorts of plants and animals. They are useful in figuring out who the father of a child is or who committed a crime.
The DNA from a PCR reaction is then run on an agarose gel. In an agarose gel, smaller pieces of DNA run faster and so are more towards the bottom of the gel. From looking at the figure on the right, can you guess who has a copy of A and B and who has two copies of A? That's right, Bob has a copy of A and B meaning he is heterozygous for this allele. Terri has two copies of A and so is homozygous.
This project was supported by the Department of Genetics, Stanford School of Medicine. Its content is solely the responsibility of the authors and does not necessarily represent the official views of Stanford University or the Department of Genetics.