Chapter Overview

Genetics is the study of the structure and function of the genomes of biological entities.
The primary levels of heredity lie in the chromosomes, genes, and the DNA molecule.
DNA is a very elongate molecule composed of deoxyribose, phosphate, and nitrogenous bases arranged in a double helix.
The two DNA strands are held together by pair bonding between matched sets of purine and pyrimidine bases: adenine pairs with thymine; cytosine pairs with guanine.
The arrangement of the base pairs along the length of DNA provides detailed instructions for the formation of proteins, key components of cell structure and metabolism.
The DNA molecule must be replicated for the distribution of genetic material to offspring.
Interpretation of the DNA is accomplished by transcription of its code into helper molecules of RNA that cooperate to translate the code into proteins.
During protein synthesis on the ribosomes, codons of mRNA are sequentially matched by a complementary anticodon on tRNA, which ensures the correct amino acid is added to the protein.
Viruses contain various forms of DNA and RNA that are translated by the genetic machinery of their host cells to form functioning viral particles.
The genetic activities of cells are highly regulated by operons, groups of genes that interact as a unit to control the use or synthesis of metabolic substances.
DNA undergoes mutations, permanent changes in its language, that alter the expression of genes and serve as a force in evolution of organisms.
Bacteria undergo genetic recombination through transfer of genes in the form of small pieces of DNA, transposons, or circular plasmids.
Forms of recombination in bacteria include conjugation, transformation, and transduction.

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