Describe the characteristics of each genetic method used in studies of heredity and variability of organisms.

Hybridological method. It consists in crossing organisms of various traits in order to study the nature of the inheritance of traits in the offspring.
The hybrid method requires certain conditions to be met.
1. In the selection of parental pairs, in each case only a certain number of alternative attributes are taken into account: one, two, three pairs.
2. Analyze the inheritance of individual alternative traits in several generations. Z. Carry out an accurate quantitative account of the inheritance of each trait in each generation.
4. Statistically reliable results of the nature of inheritance of characters are obtained only by analyzing their manifestation in a sufficiently large number of descendants.
Cytological methods. They are based on the analysis of the karyotype of individuals, the study of the behavior of chromosomes in meiosis and the quality of gametes formed. Using a microscope, determine the number of chromosomes in the cells of the body and in gametes,
When studying a chromosome set, the following rules are taken into account:
– The number of chromosomes in somatic cells of each species is normal all the time,
– In diploid organisms, each chromosome in somatic cells has a pair – a homolog, i.e., all chromosomes are paired. The haploid set of chromosomes in most organisms is available only in gametes
– Each chromosome pair is individual and differs in its parameters from the others. When staining, different pairs of chromosomes have different differential colors – the alternation of light and dark stripes. To systematize and study the karyotype, chromosomes are arranged in pairs as their size decreases,
The molecular genetic method is based on the study of the structure of genes, their number and sequence of location in DNA molecules in the chromosomes, on the identification of the nucleotide sequence of individual genes, gene abnormalities.

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