Mechanisms of Genetic Variation

These flashcards cover key vocabulary and definitions related to mechanisms of genetic variation, including mutations, repair mechanisms, and methods of horizontal gene transfer.

Mutation

Heritable changes in the DNA sequences.

Genotype

The nucleotide sequence of the gene.

Phenotype

The observed characteristics of an organism.

Wild type

A natural, nonmutated characteristic.

Mutant strain

An organism that has a mutation, showing variance in characteristics.

Forward mutation

A change from wildtype to a mutant form.

Reversion mutation

Restoration of a wild type phenotype by a second mutation at the same site.

Suppressor mutation

Restoration of wild type phenotype by a second mutation at a different site.

Point mutations

Single pair of nucleotides altered; the most common types of mutations.

Spontaneous mutations

Random changes in DNA due to errors in replication or DNA lesions.

Induced mutations

Mutations resulting from exposure to known mutagens.

Base analogues

Chemicals structurally similar to normal nitrogenous bases.

DNA modifying agents

Mutagens that change a base's structure and alter its base pairing ability.

Intercalating agents

Agents that distort DNA, leading to insertions and deletions.

Missense mutation

A substitution mutation causing a change in a single amino acid.

Nonsense mutation

A mutation that changes a normal codon into a stop codon.

Silent mutation

A mutation that alters a base but does not change the amino acid.

Frameshift mutation

A mutation caused by insertion or deletion of bases altering the reading frame.

Direct selection

Detection of mutant cells by inhibiting growth of wildtype cells.

Indirect selection

Detection of mutants by distinguishing them from wildtype based on growth conditions.

Auxotroph

A mutant microbe having a specific nutrient requirement absent in wildtype.

SOS response

A global control network comprising over 50 genes activated in response to DNA damage.

Horizontal gene transfer

Acquisition and expression of genes that originated in another organism.

Conjugation

DNA transfer via direct contact between donor and recipient cells.

Transformation

Uptake of 'naked' DNA by a recipient cell.

Transduction

Transfer of bacterial DNA by a bacteriophage.

Hfr cell

A cell with the F factor integrated into its chromosome.

F' conjugation

Transfer of an F plasmid that carries additional genes from the donor's chromosome.