Breeding and Biotechnology

Breeding: the science of creating plant varieties, animal breeds, and microorganism strains.

N. I. Vavilov identified the centers of origin of cultivated plants and discovered the law of homologous series in hereditary variation.

Breeding methods:

• Mass and individual selection.
• Hybridization: between close relatives (inbreeding), between distant species (distant hybridization).
• Polyploidy and artificial mutagenesis.

The strong vitality of F₁ hybrids: heterosis.

Biotechnology

Genetic engineering (recombinant DNA), cell engineering (cloning), and microbiological synthesis (insulin, antibiotics, vitamins).

Stages of genetic engineering:

1. Isolating the required gene (restriction enzyme cuts DNA)
2. Joining it to a vector (plasmid) (ligase stitches the fragments together)
3. Introducing it into a bacterium
4. Producing the protein (insulin)

Key facts

• Restriction enzyme cuts DNA, ligase stitches the fragments together. Vector: a plasmid or a virus.
• I. V. Michurin used the method of distant hybridization. G. D. Karpechenko created an intergeneric (radish × cabbage) hybrid.
• Polyploid: the chromosome set has increased many times over (large-fruited varieties).
• Cloning: Dolly the sheep was created in 1996.
• Transgenic organism: an organism into which a foreign gene has been introduced.
• In inbreeding, heterozygosity decreases and harmful recessive traits appear.