How specific are genes? For hair is there one for color, one for density, and one for thickness? Or 1 does all

Answer 1

Most hair characteristics are given by the action of several genes combined.
There are a few characteristics in humans that are 1 gene controlled:
Tongue rolling and ear lobe free are a couple of examples, but this is rare.

Answer 2

Well you have to understand that genes tend to work on a cellular level. There are some genes, like the one for hair color, where the gene product can be seen visually, but that is not too common. Instead changes in height, hair thickness, etc. or changes that cause disease or cancer are often due to complex interactions on a cellular level. Gout, for example, is thought to be due to problems in purine metabolism. Purines are building blocks for DNA, so it is hard to see the connection between pain in your foot at making and breaking DNA. Similarily, many viruses will turn on proteins that just turn on a whole bunch of cell proteins and it so happens that the virus on the whole benefits from the chaos.

What you have to keep in mind is that genes are the product of evolution. Evolution works best in chaotic systems... I mean it is kind of like trial and error and in that type of system you want as much trial as possible. So genes often have many targets that may have little to do with each other, but many differant genes control the various processes so that you have a combinatorial effect. That might not be to clear so I will use an example. Imagine you have 3 genes that effect 5 pathways. If you think about it, none of the genes have to be specific for the 3 genes to together control all 5 pathways. Furthermore, the cell has alot of redundancy so if you knock out a gene, there will normally be a second to back it up. Thats why removing a gene can have unpredicatble results. If you knocked out one of those 3 genes, there might be another that has a redundant effect on one pathway, but not on another.

So end conclusion is that genes are not very specific and neither are the phenotypes (hair colorr, density and thickness).

Answer 3

As a general rule, not specific at all. For example, height is a common example of multi-factorial genes - this means that there are thousands of genes that contribute to how tall a person is. That's why height is a continuum, and not two or three discrete categories.
On the other hand, eye color is probably a matter of relatively few genes, since people generally have one of several colors without TOO much individual variance.

Answer 4

There are many many genes involved in most physical traits. A gene is a part of a chromosome, and humans have 26 pairs of chromosomes. Hair color has two major genes, one that controls brown (B) vs. blonde(b) and one that controls red(r)/not red(R). Brown hair is dominant over blonde hair and not red hair is dominant over red. Therefore, someone who has two copies of the brown gene (BB) and two copies of the not red gene (RR) will probably have dark brown hair. A bb/RR combination would be pale blonde, and Bb/RR would be light brown. BB/rr would result in auburn hair, Bb/rr might be a strawberry blonde, and bb/rr would be bright red. There are several other genes besides these two that control various shades of color and highlights. I hope the letter combinations haven't confused the situation too much, but if you're familiar with Punnett Squares, they'll make sense. :)

Answer 5

Alleles are carried on chromosomes. These chromosomes are the genetic matter in the nucleus of our cells and they consist of deoxyribosenucleic acid (DNA).

Some traits are thought to be multi-allelic (they're carried on several chromosomes/alleles) while some simpler ones are on single alleles.

All of our individual traits (like hair colour etc) are interestingly determined by introns that differ from other people in the human race. That's why people are correct in saying that all people have 99% of the same genes.