Biology Compulsory 1 Chapter 5 Knowledge Points, Biology Compulsory 2 Chapter 5 Knowledge Points

Genetic mutations and other mutations are the key learning knowledge of Biology Compulsory II, in order to facilitate students to grasp its knowledge points, I have compiled the knowledge points of Chapter 5 of Biology Compulsory II for you, let's take a look.

1. Types of biological variation.

1. Non-heritable variation (caused only by environmental changes).

2. Heritable variations (caused by changes in genetic material), including: genetic mutations; genetic recombination; Chromosomal variation.

2. Heritable variation.

a) Genetic mutations.

1. Concept: The change in gene structure caused by the substitution, addition and deletion of base pairs in the DNA molecule is called gene mutation.

2. Reason: physical factors: X-ray, ultraviolet, R-ray, etc.;

Chemical factors: nitrite, base analogues, etc.;

Biological factors: viruses, bacteria, etc.

3. Features: 1) Universality.

2) Randomness (genetic mutations can occur at any stage of an organism's ontogeny; Genetic mutations can occur on different DNA molecules within cells or at different sites of the same DNA molecule).

3) Low frequency.

4) Most harmful.

5) Non-directional.

Note: Somatic mutations cannot be passed directly to offspring, but germ cells can.

2) Genetic recombination.

1. Concept: refers to the recombination of genes that control different traits in the process of sexual reproduction in an organism.

2. Type: 1) Free combination of non-allelic genes on non-homologous chromosomes.

2) Cross-swapping of non-sister chromatids during the tetrad period.

1. Chromosomal structural variation:

Example: Cat meow syndrome (partial deletion of chromosome 5).

Type: Missing, Duplicated, Inverted, Translocated (read and understood).

2. Variation in the number of chromosomes.

1. Type. 1) Individual chromosomes increase or decrease:

Example: Trisomy 21 (1 more chromosome 21).

2) Multiply or decrease in the form of a set of chromosomes:

Example: Triploid seedless watermelon.

2. Chromosomes.

1) Concept: All the chromosomes present in the gametes of diploid organisms form a chromosome set.

2) Characteristics: There are no homologous chromosomes in a chromosome set, and the morphology and function are different;

A set of chromosomes carries all the genetic information that controls the growth of living things.

3) Judgment of the number of chromosomes:

Number of chromosome groups = If there are several chromosomes with the same morphology in the cell, there are several chromosome groups.

1. Multiple:

Method: Germinated seeds or seedlings were treated with colchicine. (It can inhibit the formation of spindles, resulting in non-disjunction of chromosomes, which causes the number of chromosomes in the cell to double).

Principle: Chromosomal variation.

Example: Cultivation of triploid seedless watermelons.

Advantages and disadvantages: the cultivated plant has large organs, high yield, and rich nutrition, but low seed setting rate and late maturity.

2. Haplotype Sports:

Methods: Pollen (medicine) was cultured ex vivo.