Gene Expression and Mutation

These flashcards cover key concepts related to gene expression and mutations, including definitions and important laws of inheritance.

Gene

The unit of heredity, composed of nucleotide sequences that encode amino acids or special types of RNA.

Enzyme

A protein that catalyzes chemical reactions in the cell, mediating the assembly of nucleic acids, proteins, carbohydrates, fats, and lipids.

Mendel’s First Law

States that alternative forms of a trait (alleles) do not blend in heterozygotes and segregate during gamete formation.

Mendel’s Second Law

States that genes assort independently of one another during gamete formation because they are on different chromosomes.

Allele

One of two or more alternative forms of a gene, composed of different nucleotide sequences.

Transcription

The first stage of gene expression where an RNA copy (mRNA) is synthesized from a DNA template.

Translation

The second stage of gene expression where ribosomes synthesize a polypeptide using the mRNA nucleotide sequence.

Mutation

Any change in the genetic message of a cell; can include point mutations and chromosomal rearrangements.

Point Mutation

An alteration in the coding sequence of a gene that involves only one or a few nucleotides.

Translocation

The process where a segment of one chromosome becomes a part of another chromosome.

Inversion

An alteration where the orientation of a portion of a chromosome becomes reversed.

Spontaneous Mispairing

Point mutations that occur without exposure to mutagens, often leading to insertion errors during DNA replication.

Frame Shift Mutation

Occurs when misaligned DNA segments lead to a genetic message that is out of sync with the normal reading frame.

Free Radicals

Ionized atoms with unpaired electrons that can break phosphodiester bonds in the DNA helix, usually formed by ionizing radiation.

Pyrimidine Dimer

A crosslink formed between two pyrimidine bases that can block DNA replication if not repaired.

Biological Significance of Mutation for Evolution

Mutations in germ cells are critical for evolution as they provide the genetic variation necessary for natural selection.