What determines the dominance and recessiveness of genes?

Because (aa) is single (aa) is double (aa) is double so the double eyelids are determined by the dominant one, which is explained in the biology textbook.

aa is double, so double is obvious, if it is single, then single is obvious.

The experiment is based on the results, and your question is meaningless.

You take any family, and try it with the methods you have learned.

As for the reason why explicit is explicit ... I don't understand either.

In general, the explicit ones are indicated by capital letters

AA is dominant, AA is dominant, AA is recessive, uh, I can't tell ...... either

I don't know. Pay attention.

1. Dominant gene: The dominant gene refers to such an allele, whether the gene is homozygous or heterozygous, it will be expressed. When such alleles appear, the phenotype of the organism shows dominant characteristics.

2. Recessive genes: recessive genes are 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.

The difference between dominant genes and recessive genes: 1. Dominant genes are represented by uppercase letters, and recessive genes are represented by lowercase letters. 2. The dominant gene can often form a functional substance, such as an enzyme, while its recessive allele cannot produce this substance.

3. Dominant genes determine dominant genetic diseases, and recessive genes determine non-concomitant recessive genetic diseases. 4. Only homozygous recessive genes will show the trait, whether they are homozygous or heterozygous dominant genes, they will show the trait.

What is the dominant geneDominant and recessive genes are concepts relative to a pair of genes with relative traits, in a pair of heterozygous alleles, the gene that makes it exhibit a trait or refers to the gene that has a decisive role in that trait. There may be a dominant and recessive relationship between a pair of alleles, and if the action of one gene in the allele can inhibit the action of the other gene, we call the former gene dominant to the latter gene, and conversely, the latter gene is recessive to the previous gene.

A recessive gene is an allele that determines the trait only when the gene is homozygous for the trait to be expressed. In the heterozygous state, the phenotype of the organism shows traits determined by dominant genes. Generally, recessive genes are denoted by lowercase letters, and if the dominant homozygous for this gene is denoted as AA, then recessive homozygous is denoted as aa, and heterozygous is denoted as aa.

The dominant gene is the status quo that has been manifested, and the recessive gene is the one that has not been manifested. The traits shown by genes are usually indicated by two English letters, with the upper case being dominant and the lower case being recessive. When the dominant gene is present at the same time as the recessive gene, the trait of the dominant gene is displayed, and the recessive trait is not shown unless two recessive genes meet.

Dominant genes: genes that control the development of dominant traits. In diploid organisms, genes that are expressed in the phenotype in the heterozygous state are called dominant genes and are usually represented by a capital English letter.

The dominant gene often forms a functional substance (such as an enzyme), while its recessive allele cannot produce this substance due to a mutation in the corresponding nucleotide, so in the heterozygosity, only the dominant gene can exhibit normal function (dominant).

Recessive genes: Because the corresponding nucleotide is mutated to produce this substance, only the dominant gene can exhibit normal function (dominant) in the heterozygosity, while the recessive gene cannot manifest. 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.

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

The recessive gene finch high attack: It is the gene that dominates the recessive trait, and is used to form an allele that will only affect the phenotype if the genotype of the organism is homogeneous. The process of inheritance of recessive genes is called recessive inheritance.

Many well-known genetic diseases are recessive.

First, the nature is different.

1. Recessive gene: an allele that determines the trait will be expressed only when the gene is homozygous.

2. Dominant gene: Whether the gene is homozygous or heterozygous, it will be expressed.

Second, the relationship with heredity is different.

1. Recessive genes: Homozygous genes are either bidominant or birecessive. If dominant is represented by an uppercase letter and recessive is represented by a lowercase letter, the homozygous of the aa combination is the dominant homozygous, the homozygous of the aa combination is the recessive homozygous, and the aa of an uppercase and lowercase combination is heterozygous.

Heterozygous exhibits traits determined by dominant genes, which are the "precedence" of dominant genes.

2. Dominant genes: dominant genes control the alleles of dominant traits. In diploid organisms, genes that can behave as phenotypes in the heterozygous state are called dominant genes.

Dominant genes tend to form functional substances (such as enzymes), while the recessive alleles of dominant genes cannot produce this substance due to mutations in the corresponding nucleotides, so only the dominant genes in the heterozygotes can perform normal functions (dominant).