Lecture 17: Translation Vocabulary

Vocabulary flashcards covering key terms, RNA types, stages, enzymes, and cellular components involved in translation.

Central Dogma

The concept that cells are governed by a cellular chain of command, dictating the flow of genetic information from DNA to RNA to protein.

Codon

A set of three mRNA nucleotides that specifies a single amino acid in a polypeptide chain.

Start Codon

The specific codon AUG that signals the start of mRNA translation.

Non-sense Codons

The codons UAA, UAG, and UGA that do not code for an amino acid and signal the termination of translation.

Wobble Hypothesis

The explanation for flexible base pairing at the third base of a codon, allowing a single tRNA to pair with more than one codon.

mRNA (Messenger RNA)

A type of RNA that transmits the genetic code from DNA and features a 5' cap and 3' poly-A tail for stability.

tRNA (Transfer RNA)

A single RNA strand folded into four stems in a cloverleaf appearance that carries a specific amino acid on one end and an anticodon on the other.

rRNA (Ribosomal RNA)

The RNA component that combines with proteins to form the structure of ribosomes.

Aminoacyl-tRNA Synthetase

The enzyme responsible for accurately matching a specific tRNA with its corresponding amino acid prior to translation.

Ribosome

A molecular complex composed of large and small subunits containing rRNA and proteins, featuring A, P, and E binding sites to facilitate codon-anticodon coupling.

Initiation

The first stage of translation where the small ribosomal subunit, mRNA, initiator tRNA, and large ribosomal subunit assemble with the aid of initiation factors.

Elongation

The second stage of translation where amino acids are sequentially added in a $5' \rightarrow 3'$ direction through codon recognition, peptide bond formation, and translocation.

Termination

The final stage of translation triggered when a stop codon enters the A site, resulting in the halt of protein synthesis and release of the translation assembly.

Release Factor

A protein that binds to the A site when a stop codon is reached, causing the addition of a water molecule instead of an amino acid to release the completed polypeptide.

Free Ribosomes

Ribosomes suspended in the cytosol that primarily synthesize proteins that function within the cytosol.

Bound Ribosomes

Ribosomes attached to the endoplasmic reticulum (ER) that synthesize proteins destined for the endomembrane system or secretion from the cell.

Signal Peptide

A sequence of amino acids that marks a newly synthesizing polypeptide for targeting to the endoplasmic reticulum or for secretion.

Signal-Recognition Particle (SRP)

A protein-RNA complex that binds to the signal peptide and escorts the ribosome and nascent polypeptide to an SRP receptor on the ER membrane.

Polyribosome (Polysome)

A structure formed by multiple ribosomes simultaneously translating a single mRNA strand, enabling rapid synthesis of multiple protein copies.