Molecular Genetics EXAM 3 (copy)

Somatic Recombination

Recombination that occurs in nongerm cells, commonly referring to recombination in the immune system.

Bivalent

The structure containing all four chromatids at the start of meiosis, with two chromatids from each homolog.

Synaptonemal Complex

The morphological structure formed by paired homologous chromosomes during meiosis.

Double Strand Break Repair (DSBR) Model

A recombination model initiated by making a double strand break in one DNA duplex.

D-loop

A branched structure formed during single-strand invasion where one strand displaces its counterpart in the other duplex.

Mismatch Repair

The process that corrects mismatched sequences in heteroduplex DNA, leading to gene conversion.

Break-Induced Replication (BIR)

A process initiated by a one-ended double-strand break that can result in translocations.

Recombinase

An enzyme that catalyzes site-specific recombination.

Linkage

The term used to indicate two genes that are located on the same chromosome.

C-value

The total amount of DNA in the genome per haploid set of chromosomes.

Junk DNA

Non-coding regions of DNA that do not encode proteins but may play roles in regulation and genome stability.

Orthologous Genes

Related genes in different species that evolved from a common ancestral gene through speciation.

Synonymous Mutation

A change in DNA sequence in a coding region that does not alter the amino acid encoded.

Nonsynonymous Mutation

A change in DNA sequence in a coding region that alters the amino acid encoded.

Fixation

The process by which a new allele replaces the allele that was previously predominant in a population.

Housekeeping Gene

A gene that is expressed in all cells because it provides basic functions needed for sustenance of all cell types.