Message 227 of 238 (855021)
06-15-2019 5:51 AM
Reply to: Message 226 by Faith
06-14-2019 11:07 PM
Genes and Alleles
Oh there is a lot to correct here.
| Each gene NORMALLY has TWO alleles.|
The â€œgeneâ€ is just an area (locus) designating where a sequence of nucleotides used to build a protein is stored. The specific sequence of nucleotides at that gene locus constitutes an allele.
You get 2 copies of a gene. One on the chromosome from mom one on the chromosome from dad.
The specific alleles themselves are also inherited from the parents. Mom had 2 alleles on her 2 chromosomes, dad had 2 on his and you get one allele from each. Think of the allele as the software module occupying the area designated as the gene, the locus.
In the population there is no limit of 2 alleles for a gene. Alleles can number in the thousands. But only one appears at each locus (gene)
Your grandparents had 8 alleles on their specific genes. Depending on the sensitivity of the function all 8 alleles may be the same allele or all 8 may be different. Your mom inherited two and your dad inherited two then you inherited one from each of them.
For instance for Hemoglobin there are three different alleles. Highly conserved, sensitive to mutation. You tend not to live and procreate if you get a mutated hemoglobin allele. Your grandparents probably had only the one or maybe two of the variants in their 8 hemoglobin alleles. Hair color is not so sensitive. There are thousands of different alleles for expressing hair color. Your grandparents may have had 8 different alleles for this gene.
All alleles expressed in a population *is* the gene pool for that population.
| So what started out as a system to protect against a few hundred diseases is now scattered so that any given individual may have protection for that collection of diseases, while another individual has protection against a different collection.|
No. The immune system genes *do not* protect you from disease. They set up the mechanisms that allow your body to defend itself from disease. Even with different alleles of immunity genes your body set up the mechanisms to identify and combat invaders. Some of the proteins used may be somewhat different but the result is the same. A rhino virus in one person is treated pretty much the same as in another. The differing alleles of the immune system genes do not confer differing disease protection schemes. They only slightly alter the structures and chemistry used in setting up the full immunity processes.
| And what happens to Mendel's observations about how BB, Bb and bb are the formula for blue and brown eyes?|
That is high school genetics from 1970s. BB Bb bb are used as simple illustrations of a very complex processes. The reality is quite different. B is an allele. So is b. So are s, S, V, H, g, v, G and h. These variants are in the population and will be expressed if the parents pass them to their offspring.
You have seen about alternative splicing and isoforms. Genetics is not as simple as this BB bb stuff.
| So now you're saying the genes aren't particularly for eye color at all, but are all involved in forming all the eye functions? Is this known for sure?|
Weâ€™ve come a long way these past few decades. The proteins create the structure and the structure reflect color under certain conditions. There is no â€œeye colorâ€ gene. There is a suite of genes that give rise to the many structures in the eye and because there are different variants (alleles) to these genes the result is slight differences in structure and thus eye color person to person.
| But those thousands of alleles are scattered through the population, so the expression you say they give the gene are available only to separate individuals. Is that a good thing?|
Semantics. The â€œgeneâ€ is the locus where the control systems look for the information. The allele is that information. The gene pool for a species is made up of alleles. When we say â€œBrown Hair Geneâ€ we are actually referring to a brown hair allele at the locus of the hair color gene. If the allele is for blond hair it still is at the same locus (gene) but produces blond karatin. In knowing conversation gene and allele are pretty much interchangeable.
| Not clear what you have in mind here. "Within the parent?" "pass to a specific offspring?" For any given gene only one allele per parent will be available to pass along.|
Actually there are two alleles per parent. You only get one from each. Keeping it simple your mom has G and j alleles and your dad has M and m alleles. Doesn't matter what the trait is, it's just example. You end up with GM or Gm or jM or jm as your allele set for that trait, that gene. So if you end up with the jM set the j allele is from your mom and appears on the chromosome from your mom in the locus for that gene and the M allele is from dad and appears on your other chromosome in the gene loci. One gene with one allele from each parent on the two chromosomes you get.
| But all those mutations aren't really doing anything "different." Why should they? Most, again, are neutral anyway, not changing the protein or the protein's function.|
Take an allele, apply a mutation, you have a new allele. If itâ€™s harmful it probably wonâ€™t survive long and wonâ€™t appear in the gene pool. If itâ€™s neutral (which generally means the protein it produces is electrochemically close enough to work right) then it will just kinda hang out in various folks staying in the gene pool subject to drift and other processes including more mutation like any other gene. If itâ€™s beneficial then it will grow in prominence in the population and that allele will show up in more and more of the future population subject to drift and other processes including more mutation like any other gene.
| HOW different? IN WHAT WAY different?|
What are the differences between a wolf and a dog? What are the differences between a dandelion and a rose?
| First, as I've saying, this idea that new alleles per gene just keep accumulating is either not happening as you think it is, or it's so abnormal it can only cause problems as it does in the immune system.|
It is wrong so stop thinking alleles accumulate on genes. Alleles are the active part of the gene. It is the data used to build the protein. You only get one allele occupying one gene. You have two hair color genes so you have two alleles that actually code the specific keratin for your hair color.
| You guys make much too much of mutations. They really aren't necessary and they don't do what you think they do.|
Mutations are the machine that feeds natural selection. Change is everything in life everywhere.
Just like your confusion on gene/allele and how it all works I see you don't understand mutation and the vital role it plays in diversity.
Edited by AZPaul3, : No reason given.
Eschew obfuscation. Habituate elucidation.
|This message is a reply to:|
| ||Message 226 by Faith, posted 06-14-2019 11:07 PM|| ||Faith has responded|
|Replies to this message:|
| ||Message 228 by Theodoric, posted 06-15-2019 9:16 AM|| ||AZPaul3 has acknowledged this reply|
| ||Message 229 by Faith, posted 06-15-2019 5:51 PM|| ||AZPaul3 has responded|