Gene Expression Vocabulary

Flashcards for vocabulary review of gene expression, transcription, translation, and mutations.

Molecular Genetics Terminology

The use of appropriate terminology related to molecular genetics.

Garrod's biochemical investigation of alcaptonuria

A series of chemical reactions where the build-up of homogentisic acid was due to a defective enzyme in the metabolic pathway that breaks down the amino acid phenylalanine.

One-gene/one-polypeptide hypothesis

One gene specifies one enzyme; later updated to one gene codes for one polypeptide (or protein).

Messenger RNA (mRNA)

RNA that contains the genetic information of a gene and carries it to the protein synthesis machinery; it provides the information that determines the amino acid sequence of a protein.

Genetic code

A set of rules for determining how genetic information in the form of a nucleotide sequence is converted to an amino acid sequence of a protein; a code specifying the relationship between a nucleotide codon and an amino acid.

Triplet hypothesis

The genetic code is read three nucleotide bases at a time.

Gene expression

The synthesis of a protein based on the DNA sequence of a gene; genetic information flows from DNA to RNA to protein.

Transcription

The synthesis of RNA from a DNA template; the first step in gene expression.

Translation

The synthesis of protein from an mRNA template; the second step in gene expression.

RNA polymerase

The main enzyme that catalyzes the formation of RNA from a DNA template.

Promoter region

A sequence of nucleotides in DNA that indicates where the RNA polymerase complex should bind to initiate transcription.

Precursor mRNA (pre-mRNA)

mRNA that has not undergone processing.

Mature mRNA

mRNA that has undergone processing.

5' cap

A modified form of a guanine nucleotide which is added to the 5’ end of an mRNA molecule.

3' poly-A tail

A series of adenine nucleotides added to the 3’ end of mRNA.

Splicing

A process of excising out the introns and combining in the exons.

Transfer RNA (tRNA)

An RNA molecule that links the codons on mRNA to the corresponding amino acid for protein synthesis.

Anticodon loop

A triplet of bases positioned at one end of a tRNA that recognizes and base-pairs with a codon on mRNA during protein synthesis.

Acceptor stem

The 3’ end of a tRNA molecule that is the site of attachment for a particular amino acid, based on the anticodon.

Aminoacyl-tRNA synthetase

An enzyme responsible for attaching an amino acid to a tRNA.

Translation

One of the most energy-consuming processes of the cell.

Ribosome

A cell structure composed of proteins and rRNA that provides the site where protein synthesis occurs.

Ribosomal RNA (rRNA)

the RNA that is associated with proteins in the ribosome

Polyribosome

A structure composed of multiple ribosomes along a strand of mRNA.

Start codon

A triplet of three bases that specifies the first amino acid of a protein.

Reading frame

Collectively, the codons of mRNA that are read to produce an amino acid sequence; it is set by the start codon.

Peptide bond

A covalent bond formed between two amino acids during protein synthesis.

Mutation

A permanent change in the nucleotide sequence of a cell’s DNA.

Single-gene mutation

A mutation that involves changes in the nucleotide sequence of one gene.

Chromosome mutation

A mutation that involves changes in chromosomes and may involve many genes.

Point mutation

A mutation involving a single base pair substitution, insertion, or deletion.

Frameshift mutation

A mutation caused by the addition or deletion of a number of nucleotides not divisible by three, resulting in a change in the reading frame.

Silent mutation

A mutation that does not change the amino acid sequence of a protein.

Missense mutation

A mutation that changes the amino acid sequence of a protein.

Nonsense mutation

A mutation that shortens a protein by introducing a stop codon.

Transposon

A short segment of DNA capable of moving within the genome of an organism; also called a jumping gene.

Mutagen

An event or substance that increases the rate of changes to the DNA sequence of an organism’s genome.

Gene regulation

The control of the level of gene expression.

Constitutive gene

A gene that is constantly being expressed; It does not undergo regulation of expression.

Operon

A cluster of genes grouped together under the control of one promoter; occurs in prokaryotic genomes.

Operator

A repressor protein that binds to a DNA sequence element; it regulates transcription.

Repressor

A protein that binds to a particular DNA sequence to regulate transcription; it inhibits the transcription of a gene or genes.

Activator

A protein that binds to a particular DNA sequence to regulate transcription; it increases the rate of transcription of a gene or genes.

Transcription factor

One of a set of proteins required for initiation of transcription; it is required for the RNA polymerase complex to bind to the promoter.

RNA interference

The regulation of gene expression by small RNAs; it inhibits gene expression by degrading mRNA or inhibiting translation.