Let's start with mitosis. This is how human cells multiply in your body. You start with 23 pairs of chromosomes, duplicate them, and then separate the duplicates into different cells. (I apologize if the background is black. I included blockcolor code, but apparently it doesn't work for everyone).
Meiosis is a bit more complicated. This is the process that creates egg and sperm, each of which only carries one copy of each chromosome instead of the pairs found in your other cells in your body.
In the first step the chromosomes have already replicated, so they are at the sister chromatids stage in the mitosis picture. This first step is the same as mitosis. However, things get a bit different from here. In meiosis I you get recombination between homologous chromosomes which is often called "crossing over". This usually happens about once per chromosome. After the chromosome pairs have swapped pieces, the pairs are separate from one another. After the pairs are separated, the sister chromatids are separated. What you end up with is sex cells with only half the number of chromosomes. When they combine they produce the usual 23 pairs of chromosomes.
You have a misunderstanding of the scope we are addressing. We are not talking a few or few dozen mutations between some pair of close species. Weâ€™re talking billions of them.
In humans between parents and child there are on average about 100 mutations introduced into the genome. 100 mutations introduced into the genome per birth. Thatâ€™s a lot of mutations in a population of billions of breeding beings.
Now, take that times how many generations for millions of years? The genome available to the breeding population now is millions of mutations different from the starting population millions of years ago.
No one can identify the chain of how many of what groups of mutations were responsible for the path taken by nature from rat to whale.
A mutation or mutations that could turn a dog into a different species would have to change the dog genome in some way, otherwise mutations would just vary the dog stuff and it would still be a dog.
Youâ€™re not half wrong. Whatever species bud off the dog species in the next million years or so will still have that dog lineage and that, by then heavily mutated, dog genome.
Of the billions of new genes available to a population a million years from now the beneficial ones will have survived. By the billions. By definition the less beneficial the less it appears in the gene pool. The future genome will be built by only the more successful alleles of which many billions would have arisen in that past million years.
Other control groups of DNA/RNA. All subject to mutation of course.
B and b are alleles. They are on the DNA strand like any other allele and get expressed/activated/transcribed into protein in the same way as any other allele when the full chain of the control groups has worked its magic. The control groups are activated/controlled by yet other control groups which determine which allele gets activated for how long.
Well I can't help with Dem Nutz but that is the scoop from the reality side of the fence.
You know, Love, you can still be a good biblical conservative alt-reich racist commie Stalinist fascist theocrat and still understand the true nature of evolution. You know that right? The two arenâ€™t necessarily exclusive.
The B and the b show up as sequences of DNA and there will be a range of DNA sequences that correspond to each. Alleles are largely identified by effect, but if different mutations cause the same effect the resulting alleles would usually be considered distinct (assuming we know).
I should point out, again, that the relationship between genes and morphology is complicated so the â€œeffectâ€ is not a guaranteed - or simple - thing once you get beyond protein sequences.