How to judge the recessive and dominant nature of genes

Explicit and implicit are relative.

For example, the expression gene of double eyelids is A, and the performance gene of single eyelids is A, so there are three types of eyelid gene types: AA, AA, and AA.

If the gene is AA and manifests as a double eyelid, the double eyelid is dominant;

If the gene is AA and appears as a single eyelid, the single eyelid is dominant.

In reality, AA manifests as double eyelids, so double eyelids are dominant.

On a pair of chromosomes, if there is a double eyelid gene, then that person is a double eyelid. For a person to have a single eyelid, both of the person's chromosomes must be single eyelid genes. So it's a matter of how dominant and recessive a gene is determined by its combination.

A pair of chromosomes can be called dominant if it contains only one gene for that trait, and a recessive gene if both must be of the same gene in order to exhibit its trait.

What is shown is dominant, and what is hidden is recessive, but that's a matter of genes.

The characteristics that are not manifested are recessive, and the obvious ones are explicit.

I wonder if you studied biology in high school? If you have learned, this question is not difficult, if you have not learned, this question is not clear in a few words.

Double eyelids and single eyelids are a pair of relative traits in humans, controlled by dominant gene A and recessive gene A, respectively

If a person decides that the genetic combination of the eyelids is AA or AA, the person has double eyelids.

If it's AA, the person has a single eyelid.

And how to tell if a gene is dominant and recessive, there are several methods. If hybridization experiments and cross-crossing experiments are carried out, it can be determined.

If you haven't studied in high school, it's enough to talk about this, and you can check the details of the process on the Internet, and I won't be **.

This is the result of genetics.

Out of nothing, there is something hidden out of nothing.

Dominant recessive genes.

There are two ways to judge, namely:

1. Forward thrust method: after homozygous hybridization, the traits that are easy to appear in the offspring are dominant, such as tall stem A, short stem A, hybridized with homozygous high stem Aa and homozygous dwarf stem Aa, the offspring show high stem, then the high stem is the dominant trait, so the A gene is the dominant gene.

2. Reverse deduction method: after heterozygous (AA) hybridization, the offspring will have trait separation, then the new trait is recessive, and the control gene is also recessive gene. If the tall stem AA is inbred with the tall rolling stem AA, and the offspring appear tall stem and short stem, then the short stem is a new trait that is recessive, so A is a recessive gene.

Something out of nothing, "have" is hidden, referring to the traits that the parents do not have, but the offspring shows).

The specific embodiment of dominant and recessive genes is as follows:

1. Dominant allele is the gene that controls the development of dominant traits. In diploid organisms, genes that can be expressed in the phenotype in the heterozygous state are called dominant genes and are usually represented by an English letter in large capital letters.

The dominant gene often forms a functional substance (such as an enzyme), while its recessive allele is recessive.

then due to the corresponding nucleotides.

A closed mutation occurs and the substance cannot be produced, so in the heterozygosity, only the dominant gene exhibits normal function (dominant);

2. The recessive gene cannot produce this substance due to the mutation of the corresponding nucleotide, so in the heterozygosity, only the dominant gene can show normal function (dominant), while the recessive gene cannot manifest.

In particular, catalyze cellular chemical reactions.

The enzymes used in very small quantities can be recycled, so the enzymes produced by the dominant gene alone can maintain a normal phenotype, so the effect of the recessive gene is masked.

Dominant gene: A gene used to represent a certain sex in a heterozygous that is chiral.

Recessive genes: Used to indicate genes that manifest only in homozygous auspicious silver states.

In the title, dominant genes are generally indicated by uppercase letters, and recessive genes are generally represented by lowercase letters.

If you want to know whether a trait is dominant or recessive in life, you can check the relevant information. If you need to judge the dominant recessiveness when doing the question, you generally look at the next generation, for example: the homozygous hybridization of two relative traits, and the traits shown by the offspring generation are dominant traits; The parents are heterozygous, and the trait with a higher number of offspring is the dominant trait, and the trait with a smaller number of potatoes is the recessive trait.

Among human traits, single eyelids are recessive traits, and double eyelids are dominant traits.

The color of the human eye is more complex, and it is not easy to judge the explicit and recessive. In animals, there are more questions about the eye color of fruit flies, with red eyes being dominant and white eyes being recessive.

The mantra for judging the explicit and recessive nature of genes is: there is no dominance in the middle, and there is a celebration and defeat out of nothing is recessive.

1. The child is normal and the parents are sick, the father is sick, the daughter is sick, and the mother is sick, which is accompanied by x dominant inheritance;

2. The child is normal and the parents are sick, the father is not sick, the daughter is not sick, and the child is not sick, which is autosomal dominant inheritance;

3. The normal children of both parents are sick, the mother is sick, the son is sick, and the father is sick, which is accompanied by x recessive inheritance;

4. The disease of the normal children of both parents, the disease of the mother and the son, and the disease of the father of the daughter are not disease, which is autosomal recessive inheritance.

Judgment of genotype: Determine the inheritance mode that the dry letter conforms to, find out the dominant recessive nature of the gene, and according to the dominant recessiveness, the genotype can be introduced.

Dominant gene: Used to describe a Puna allele that affects phenotype in both homogeneous and heterogeneous situations, is called dominant. The process of inheritance determined by dominant genes is called dominant inheritance.

The inheritance determined by recessive genes is called recessive inheritance.

Recessive genes: are the genes that dominate recessive traits. In diploid organisms, genes that can be phenotypically displayed in the homozygous state, but not in the heterozygous state are called recessive genes.

There are dominant and recessive characteristics in genes, and generally speaking, the final characteristics that can be seen are the results of dominant gene expression, while what cannot be seen are the results of recessive gene expression. In particular, the enzymes that catalyze cellular chemical reactions are used in very small quantities and can be recycled, so the enzymes produced by the dominant gene alone can maintain a normal phenotype, so the effect of recessive genes is masked.