0.1 Basic principles of genetics  (Page 11/19)

Recombinant DNA technology - genetic engineering - has made it possible to gain insight into how genes work. In cases where it is impractical to test gene function using animal models, genes can first be expressed in bacteria or cell cultures. Similarly, the phenotypes of gene mutations and the efficacy of drugs and other agents can be tested using recombinant systems. This transfer may occur naturally through transformation. This is an idea that geneticists are realizing is more important than previously thought.

The techniques for gene manipulation as well as for gene transfer are described in detail in the lectures 14 and 15.

Lecture 12. a genome is an entire set of genes

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In classical genetics, the genome of a diploid organism including eukarya refers to a full set of chromosomes or genes in a gamete ; thereby, a regular somatic cell contains two full sets of genomes. In a haploid organism , including bacteria, archaea, virus, and mitochondria, a cell contains only a single set of genome, usually in a single circular or contiguous linear DNA (or RNA for some viruses). In modern molecular biology the genome of an organism is its hereditary information encoded in DNA (or, for some viruses, RNA ).

The genome includes both the genes and the non-coding sequences of the DNA. The term was adapted in 1920 by Hans Winkler , Professor of Botany at the University of Hamburg , Germany . The Oxford English Dictionary suggests the name to be a portmanteau of the words gene and chromosome; however, many related -ome words already existed, such as biome and rhizome , forming a vocabulary into which genome fits systematically. [1]

More precisely, the genome of an organism is a complete genetic sequence on one set of chromosomes ; for example, one of the two sets that a diploid individual carries in every somatic cell . The term genome can be applied specifically to mean that stored on a complete set of nuclear DNA (i.e., the "nuclear genome") but can also be applied to that stored within organelles that contain their own DNA, as with the mitochondrial genome or the chloroplast genome. Additionally, the genome can comprise nonchromosomal gentic elements such as viruses , plasmids , and transposable elements [2] . When people say that the genome of a sexually reproducing species has been " sequenced ," typically they are referring to a determination of the sequences of one set of autosomes and one of each type of sex chromosome , which together represent both of the possible sexes. Even in species that exist in only one sex, what is described as "a genome sequence" may be a composite read from the chromosomes of various individuals. In general use, the phrase "genetic makeup" is sometimes used conversationally to mean the genome of a particular individual or organism. The study of the global properties of genomes of related organisms is usually referred to as genomics , which distinguishes it from genetics which generally studies the properties of single genes or groups of genes.