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Blue eyes, and a star-shaped iris pattern. Blue eyes are the newest mutation in our genome. Blue-eyed is only about 10,000 years old, which means that there were no blue-eyed humans until the end of the last ice age.
Regardless of their utility, Blue Eyes has had amazing success in promoting itself, and in a very short period of time, the world's population has grown from 0 to 15%. This is the extremely positive choice pressure.
Fact: We all start with blue eyes, and then as the eyes mature, usually while still in the womb, the pigment will coat the eyes. Some babies are born with blue eyes and then, to the disappointment or indifference of their parents, turn green, gray, hazel or brown in the first months of life.
Therefore, it is clear that blue eyes are a point mutation, and at some point, the genes of pigmentation cannot be expressed, and they remain blue. The evolutionary advantages of blue eyes are unknown (other than sheer sexual appeal, which may be enough in itself), other than getting many Hollywood actors and actresses to contract films. I would like to add that this attraction applies to all races as well, not just Caucasians.
What geneticists want to know, know now!
Blue eyes are recessive – by definition recessive genes must be homozygous – (2) recent mutations – the chances of further mutations are small because mutations are a function of time – then theoretically all blue-eyed people should have the same blue color. However, there are many different shades of blue, which should not be possible genetically and statistically. So, there's more at play here than meets the eye.
Side note: Blue eyes produce sub-mutations in 10,000 years, while brown eyes take about 100,000 years! In other words, blue eyes are an out-of-control mutation that produces sub-mutations ten times faster than brown eyes – not at all on the charts – and we don't know why.
This does not explain this even when the positive selection pressure of the rate of accelerant mutation is taken into account.
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I don't think so, because this disease is very rare, and none of us have been exposed to it at all, so I don't think there is.
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I think it's the change in the color of the pupils, and some people have very strange pupil colors after genetic mutations.
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1. Static mutations.
Static mutation is a gene mutation that always occurs at a certain frequency in each generation of an organism, and can be relatively stable with the reproduction and alternation of generations.
a) Point mutations: changes in a single base or base pair in a DNA polynucleotide strand.
1. Base substitution: a mutant form in which a specific base or base pair in the polynucleotide chain of a DNA molecule is replaced or replaced by other bases or base pairs.
2. Frameshift mutation: due to the insertion or deletion of base pairs in the genomic DNA polynucleotide chain, some or all of the triplet genetic codon combinations have been changed since the insertion or deletion point.
2) Deletion, insertion, and rearrangement of small fragments.
1. Microdeletion: caused by a small fragment not being copied normally or failing to be repaired during the repair process of DNA replication or damage.
2. Micro-insertion: During the process of DNA replication or damage, a small fragment is inserted into the DNA strand, and the result is a micro-insertion of the corresponding small fragment in the new strand.
3. Rearrangement: When there are more than two breaks in the DNA molecule, the two ends of the small fragments formed are reversed and reconnected, or different fragments change the original structural order and reconnect.
2. Dynamic mutations.
The abnormal changes or diseases of some monogenic inherited traits are caused by the amplification of some short tandem repeats in the DNA molecule, especially the trinucleotide tandem repeats of the gene coding sequence or flanking sequence, because the number of tandem trinucleotide repeats can show an increasing cumulative mutation effect with the transmission of generations, so it is called dynamic mutation.
In biology, a mutation is a change in the nucleotide sequence in the genome of an organism, virus, or extrachromosomal DNA. Genetic mutations include point mutations caused by a single base change, or deletions, duplications, and insertions of multiple bases.
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Purine is replaced with purine, and pyrimidine is replaced with pyrimidine source envy point mutation.
Point mutations in which purines are replaced with pyrimidine, or pyrimidines are replaced with purines.
Mutations in DNA cause codons in mRNA to change to codons that encode another amino acid. For example, when the AGG conversion mutation in DNA becomes AGG, lysine is replaced by arginine, but because the two amino acids are basic amino acids and have similar properties, the function of the genetically encoded protein has not changed, and this missense mutation is also calledNeutral mutations, the second nucleotide in this hail large codon that causes the neutral mutation is also called"Generalized ciphers".
Mutations in the DNA cause the codons in the mRNA to change to a kind of stop code.
Although the mutation of DNA causes the codon in the mRNA to change to another codon, it does not change the encoded amino acid due to the degeneracy of the codon.
The insertion or deletion of amino acids in the DNA that is not equal to a multiple of 3 can cause changes in the reading frame of the mRNA.
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A mutation from a dominant gene to a recessive gene is called a recessive mutation, and a mutation from a recessive gene to a dominant gene is called a dominant mutation. The vast majority are recessive mutations.
1) For sex cells:
If it is a dominant mutation, i.e., AA AA, it can be passed on to the offspring through the fertilization process and manifest itself immediately.
If it is a recessive mutation, i.e., AA AA, it does not manifest itself in the present generation and can only be manifested when the second-generation mutated gene is homozygous.
2) For somatic cells:
If there is a dominant mutation, the contemporary manifestation coexists with the original traits, forming a mosaic. The earlier the mutation, the greater the extent, and vice versa. Many of the "bud changes" on fruit trees are caused by somatic mutations, and once found, they can be propagated and preserved by cuttings, grafting or tissue culture.
If it is a recessive mutation, it does not manifest itself in contemporary times.
Genetic mutations cause the original gene to become its allele and is not directive: i.e., a gene can mutate in different directions; It can be a dominant mutation or a recessive mutation, but more often it is a recessive mutation.
Gene mutation is not the same as gene deletion, gene mutation is the addition, deletion or replacement of base pairs inside the gene, the gene is still there, but it has changed, while gene deletion is a chromosome structural variation, it is the deletion of the previous segment of the chromosome that causes the entire gene to be missing.
It can't be understood that way, these are two different levels of concept. One is from the micro and the other is from the relative macro. Gene mutation only refers to the variation of gene segments, while chromosomal variation is only the change of the entire chromosome, which cannot be measured by genes, there are too many. >>>More
For humans, genetic mutations can be useful or harmful.
Mutagenesis breeding. This is a useful aspect of genetic mutations by inducing a large and diverse number of genetic mutations in organisms, so that excellent varieties can be bred according to needs. Before the discovery of chemical mutagens, radiation was mainly used as a mutagen in plant breeding. After the discovery of chemical mutagens, the means of mutagenesis increased greatly. >>>More
Genetic reasons, either because of low immunity, irregular diet, staying up late at night, or often eating some high-salt and high-calorie foods, may lead to malignant tumors.
It's "which"), baobab (you can get water from it), rubber tree (can be used to make rubber), ......