Chapter 8: DNA Structure and Function

activator

Transcription factor that increases the rate of transcription when it binds to a promoter or enhancer.

anticodon

In a tRNA, set of three nucleotides that base-pairs with an mRNA codon.

bacteriophage

Type of virus that infects bacteria.

base-pair substitution

Type of mutation in which a single base pair changes

codon

In an mRNA, a nucleotide base triplet that codes for an amino acid or stop signal during translation.

deletion

Mutation in which one or more nucleotides are lost from DNA.

differentiation

Process by which cells become specialized during development; occurs as different cells in an embryo begin to use different subsets of their DNA.

DNA ligase

Enzyme that seals strand breaks or gaps in double-stranded DNA.

DNA polymerase

Enzyme that carries out DNA replication. Uses a DNA template to assemble a complementary strand of DNA.

DNA replication

Process by which a cell duplicates all of its DNA before it divides.

epigenetic

Refers to potentially heritable mechanisms that stably alter gene expression without changing the DNA sequence.

exon

Nucleotide sequence that remains in an RNA after post-transcriptional modification.

gene

Chromosomal DNA sequence that encodes an RNA or protein product.

gene expression

Multistep process by which the information in a gene guides assembly of an RNA or protein product. Includes transcription and translation.

genome

An organism’s complete set of genetic material.

homeotic gene

Type of master gene; its expression triggers formation of a specific body part during development.

insertion

Mutation in which one or more nucleotides become inserted into DNA.

intron

Nucleotide sequence that intervenes between exons and is removed during post- transcriptional modification.

master gene

Gene encoding a product that affects the expression of many other genes.

mutation

Permanent change in the DNA sequence of a chromosome.

operator

Part of an operon; a DNA binding site for a repressor.

operon

Group of genes together with a promoter–operator DNA sequence that controls their transcription.

primer

Short, single strand of DNA or RNA that base-pairs with a specific DNA sequence and serves as an attachment point for DNA polymerase.

promoter

In DNA, a sequence that is a site where RNA polymerase binds and begins transcription.

repressor

Transcription factor that slows or stops transcription.

RNA polymerase

Enzyme that carries out transcription.

semiconservative replication

Describes the process of DNA replication in which one strand of each copy of a DNA molecule is new, and the other is a strand of the original DNA.

transcription

Process in which enzymes use DNA as a template to assemble RNA. Part of gene expression.

transcription factor

Regulatory protein that influences transcription by binding directly to DNA; e.g., an activator or repressor.

translation

Process in which a polypeptide chain is assembled from amino acids in the order specified by an mRNA.