Cell Bio - Unit 2 - Genetic Variation

Front 1

What are 2 conditions of change that lead to variation?

Back 1

*must be heritable - affect germ line
*must not prevent the individual from reproducing

Front 2

Describe the main sources of genetic variation.
*There are 6 listed in the notes.

Back 2

*Mutation within a gene - point mutations: change a single nucleotide, duplicate or delete one or more nucleotides in gene DNA sequence usually a result of rare “mistakes” made during DNA replication or failures in DNA repair after DNA damage.
*Gene duplication:
existing gene, its part or large segment of DNA can be duplicated.
It creates a set of closely related genes in a single cell. After additional mutations in cell progeny, duplicated genes can assume functions distinct from those of the original gene *source of genetic novelty for evolving organisms.
*Gene deletion:
Individual genes or blocks of genes can be lost through chromosome breakage and failures to repair.
*Exon shuffling:
two or more existing genes can be broken and rejoined to make a hybrid gene containing DNA segments from different genes.
*Horizontal (intercellular) gene transfer:
piece of DNA can be transferred from the genome of one cell to the genome of another cell or to the genome of another species.
*Movement of transposable elements:
cause of often observed “spontaneous” mutations, can create new exon arrangements - new genes.

Front 3

Define: point mutation.

Back 3

A mutation that changes a single nucleotide.

Front 4

Define: conjugation.

Back 4

Process by which bacterial cells can horizontally transfer DNA.
-Plasmids often carry genes for antibiotic resistance and can be transferred from species to species.