Translation, Protein Synthesis, and Gene Expression

Vocabulary flashcards covering the key terms, molecular components, and concepts of translation, protein synthesis, and gene expression.

Peptidyltransferase

An enzyme that catalyzes the formation of a peptide bond between adjacent amino acids during protein synthesis.

Peptide bond

The chemical bond created between amino acids by peptidyltransferase to build a polypeptide chain.

Stop codon

A messenger RNA codon (such as UAA) that does not code for an amino acid and signals the ribosome to terminate translation and release the protein.

AUG

The messenger RNA start codon that signals the ribosome where translation begins and specifies the first amino acid, methionine.

Initiation complex

A complex assembled at the start of translation consisting of the 30S ribosomal subunit, formylmethionyl-tRNA, messenger RNA, and initiation factors, later joined by the 50S ribosomal subunit.

P site (Peptidyl site)

The ribosomal binding site that initially holds the transfer RNA carrying formylmethionine and subsequently holds the tRNA attached to the growing peptide chain.

A site (Acceptor site)

The ribosomal binding site where an incoming transfer RNA carrying the next specified amino acid enters and binds to its complementary codon.

E site (Exit site)

The ribosomal site from which an empty transfer RNA is released into the cytoplasm after transferring its amino acid.

Polysome

A structure defined as many ribosomes simultaneously attached to and translating the same messenger RNA transcript.

$NH_2^+$ end

The positive terminal end of an amino acid chain, which is always located at the initiating methionine.

$COO^-$ end

The negative carboxyl terminal group that designates the very last amino acid in a synthesized protein chain.

Phosphodiester bond

The type of chemical bond that holds together the backbone of DNA.

Hydrogen bond

The bond type responsible for holding together the complementary rungs of the DNA ladder.

Hydrophobic

Meaning scared of water; describes amino acids that avoid aqueous environments and tend to bury themselves inside lipid membranes.

Hydrophilic

Meaning water-liking; describes amino acids that prefer to interact with water and remain exposed in the cytoplasm.

Phospholipid bilayer

A double layer of fatty lipid molecules forming cellular and nuclear membranes that regulates the movement of liquids into and out of the cell.

Active site

The specific functional nooks and crannies created when a polypeptide chain folds and twists into its three-dimensional conformation.

Alleles

Different variations or forms of a gene that can result in slight amino acid sequence changes and alter protein activity.

Phenotype

The observable physical characteristics and traits of an organism, determined by both genetic makeup and environmental factors.