What is the essence of Wendy Harberg s law in biology and why?

Landlord, I'll correct it first, it's Hardy Wengerberg balance, not the one you said...

I'm a junior in high school, and as for Harwin, it should be the content of the sophomore year of high school, which can be summed up as (a+b)2 a2+2ab+b2, (that 2 is squared!) As for why, it means that the genotypes of the two individuals are AB and AB, and the hybridization will produce a AA (a squared), a BB (a squared), and two AB genotypes.

This is mainly about the calculation of genotype frequency, if the landlord is to solve the problem, or write down the inhumane checkerboard.

Pure handwriting, hope.

Back upstairs, the answer on the first floor was correct.

Hardy-Weinberg Equilibrium (Harwin's Law): Within a sufficiently large Mendelian population (i.e., a randomly mated population), gene frequencies and genotypic frequencies remain constant across generations of the population, regardless of the effects of selection, mutation, migration, and gene drift.

Considering a pair of alleles with a dominant and recessive relationship, the population mates randomly, and the frequencies of the three genotypes d(aa), h(aa), and r(aa) are squared of p, 2pq, and q, respectively. The sum of the three is equal to 1.

Hardy Weinberg's Law" refers to the ideal state of eachAllelesThe frequency of the allele and the genotype frequency of the allele are stable in heredity, i.e., the genetic balance is maintained.

This law is applied in biology, ecology, and genetics.

Conditions: The population is large enough; random mating between individuals in the population; There are no mutations; There is no choice; There is no migration; There is no genetic drift.

Overview. The frequency of each gene at this time.

When there is only one pair (aa) of alleles, let the frequency of gene a be p and the frequency of gene a be q, then a+a=p+q=1, aa+aa+aa=p +p +2pq+q =1.

Hardy-Weinberg's law of equals states that gene frequencies and genotype frequencies remain constant in the absence of migration, mutation, and selection for a large, randomly mated population.

HardyWeinberg's law refers to the ideal state that eachAllelesThe frequency of is stable in heredity, i.e., the genetic balance is maintained.

Condition met: The population is large enough.

random mating between individuals in the population;

There are no mutations; There is no choice;

There is no migration; There is no genetic drift.

Hardy Weinberg's Law For a large and randomly mated population, gene frequency.

and genotype frequencies remain constant in the absence of migration, mutation, and selection.

Relevant significance

1) The Law of Genetic Equilibrium.

The genetic law of population gene bench frequency and genotype frequency is revealed, according to which the genetic performance of the population can be kept relatively stable, which is the theoretical basis for livestock and poultry breeding.

2) According to the law of genetic equilibrium, in livestock and poultry breeding, the method of breaking the original genetic balance of the population and then establishing a new genetic balance can be adopted to improve the original breed or create a new variety, which is the theoretical basis for the breeding, strain breeding and cross-breeding of the breed.

3) The law of genetic equilibrium reveals the relationship between gene frequencies and genotype frequencies in a random mating population, thus providing a method for calculating gene frequencies and genotype frequencies in different populations under different circumstances, which can be used to make breeding more predictable.

The "Hardy-Weinberg law" means that in an ideal state, the frequency of each allele is stable in heredity, that is, the genetic balance is maintained.

At this time, the frequencies of each gene and each genotype have the following equation and remain unchanged: when there is only one pair (aa) of alleles, let the frequency of gene a be p and the frequency of gene a q , then:

a+a=p+q=1，aa+aa+aa=p2+2pq+q2=1 。

Hardy-Weinberg Equilibrium For a large, randomly mated population, gene frequencies and genotype frequencies remain constant in the absence of migration, mutation, and selection.

The Hardy-Weinberg law, also known as the "law of genetic equilibrium" or "Hardy-Weinberg equilibrium law", was independently proved by the British mathematician G. H. Harold Hardy and the German physician Wilhelm Weinberg in 1908 and 1909 respectively. In population genetics, the Hardy-Weinberg law is primarily used to describe the relationship between allele frequencies and genotype frequencies in populations. The main content is:

Ideally, gene frequencies and genotypic frequencies in a population remain constant and in equilibrium over multiple generations (not affected by specific interfering factors, such as non-random mating, selection, migration, mutation, or limited population size). ”

In fact, there will always be one or more distractions. Therefore, the Hardy-Weinberg law is not possible in nature. Genetic equilibrium is an ideal state and is used as a benchmark for measuring genetic alterations.

The simplest example is two alleles located at a single locus: the dominant allele is denoted a and the recessive allele is denoted a, and their frequencies are denoted p and q, respectively. Frequency(a) = p; Frequency(a) = q; p + q = 1。

If the population is in equilibrium, then we can get.

Frequency of homozygous aa in the population (aa) = p2

Frequency of homozygous aa in the population (aa) = q2

Frequency of heterozygous aa in the population (aa) = 2pq

The Hardy-Weinberg law, also known as the law of genetic equilibrium, refers to the fact that in an ideal state, the frequency of each allele and the genotype frequency of the allele are stable in heredity, that is, the genetic balance is maintained. There are 5 conditions that must be met for this ideal state:

The population is large enough; Individuals in a population can mate randomly; No mutations occurred; No new genes have been added; There is no natural selection. At this time, the frequencies of each gene and each genotype have the following equation relationship and remain unchanged: Let a=p, a=q, then a+a=p+q=1, aa+aa+aa=p +2pq+q =1.

Hardy-Weinberg Equilibrium LawFor a large, randomly mated population, gene frequencies and genotype frequencies remain constant in the absence of migration, mutation, and selection.

Some populations that do not conform to genetic equilibrium can reach genetic equilibrium after one generation of free mating, at which point the law of genetic equilibrium can be applied to find the genotype frequency of offspring.

For example, 20% of AA individuals, 40% AA individuals, and 40% AA individuals in a certain group, AA individuals cannot mate, and other individuals can mate freely, and the proportion of each genotype in the next generation of individuals is obtained.

In this problem, the parent individual obviously does not meet the genetic equilibrium, so he often chooses to solve it directly. In this way, it is necessary to analyze the four mating methods and then inductively synthesize (there are four combinations of male and female individuals in AA and AA free mating), which is more cumbersome. In fact, the law of genetic equilibrium can also be applied to this question, and the answers and reasons are as follows:

In aa and aa individuals, the frequencies of the two genes are determined, a=, a= after one generation of free mating, the offspring can reach genetic equilibrium, then aa=, aa=, aa=.

Hardy-Weinberg Law In a random mating population, if a locus has two alleles A and A with the frequencies of P and Q, and the frequencies of genotypes Aa, AA, and AA are P2, 2Pq, and Q2, respectively, the population is genetically balanced and does not change with generations. The constant relationship between the allele frequency (the ratio of the number of alleles in a locus to all alleles in a locus) and the genotype frequency (the ratio of the number of individuals of a genotype to the total number of individuals in the population) of a genetically balanced population was independently discovered by the British mathematician Hardy (and the German physician Weinberg (respectively discovered in 1908, called the Hardy-Weinberg law, also known as the genetic equilibrium law). The conditions for maintaining genetic balance are:

The population is infinite, with no mutations, selection, migration, and genetic drift. The significance of the Hardy-Weinberg law is, theoretically, the cornerstone of the theory of population heredity and quantitative heredity, and the genetic model and parameter estimation of the two branches of genetics are derived from this law. In practice, it reminds us not to make the population too small when introducing, retaining, dividing and establishing inbred lines, otherwise, it will lead to changes in the allele frequency and genotype frequency of the population, which will lead to the loss of the "caste" or some excellent economic traits of the original variety (strain).

The product represents the mating result and the original ratio is meaningless.

It should be noted that in a certain generation, the genotype frequency of this generation can be used to calculate the gene frequency of that generation, and if the genotype frequency obtained by using the gene frequency of this generation, it is not the genotype frequency of this generation, but the genotype frequency of the next generation. Only by grasping the essence of Hardy-Weinberg's law can we flexibly apply it to specific problems.

In addition, some populations that do not conform to genetic equilibrium can reach genetic equilibrium after one generation of free mating, and the law of genetic equilibrium can also be applied to find the genotype frequency of offspring.

Step 1: Calculate the gene frequencies for a and a in the first year a= (400x2 +500x1) 1000x2= 65 a=1- 65=35

The second part of the genetic equilibrium is to bring in the current genotype frequency and gene frequency aa: 65%x65 = ≠ 40 aa: 65%x35%x2=

AA : 35%x35 = ≠10%, so the first generation has not yet reached the balance of data.

In a population in genetic equilibrium, the population data are generally consistent with the data, which is the actual genotype frequency = the actual gene frequency.

So in enough reproductive generations will be slowly reached.

That is, after 3 generations, the genetic balance in the data can also be reflected.

So aa: 65%x65=

aa ： 65%x35%x2=

aa ： 35%x35﹪=

**If you don't understand, please ask if you understand, and if you understand, you can adopt it.

Since it is a genetically balanced population, the genotype frequency of aa is the square of the frequency of the a gene, aa400

aa500aa100

So a gene frequency = 65%.

A gene frequency = 35%.

aa = 65% squared =

aa = 35% squared =

Hardy Weinberg's law is the law of genetic equilibrium, which refers to the fact that in a large randomly mated population, gene frequencies and genotype frequencies are passed on from generation to generation without migration, mutation, or selection, and genotype frequencies are determined by gene frequencies.

Example: What is the potential danger to an isolated and significantly reduced population?

a. Loss of genetic diversity.

b. Tend to select and mate.

c. Reduced gene flow.

d. Hardy Weinberg's balance is unstable.

D was chosen because an isolated population that has been greatly reduced in number is prone to genetic drift, which leads to changes in gene frequencies and upsets the genetic balance.