Cell Biology – Lecture 7: Translation

Vocabulary flashcards covering the major terms and concepts from Lecture 7 on translation, including mRNA structure, tRNA function, ribosome anatomy, three stages of translation, decoding mechanisms, and regulation.

Translation

The cellular process in which ribosomes synthesize proteins by decoding the nucleotide sequence of mRNA into an amino-acid sequence.

mRNA (messenger RNA)

Single-stranded RNA that carries the genetic information copied from DNA in the form of codons to the ribosome for protein synthesis.

rRNA (ribosomal RNA)

RNA that combines with proteins to form ribosomes and catalyzes peptide-bond formation during translation.

tRNA (transfer RNA)

Adaptor RNA molecules that deliver specific amino acids to the ribosome by pairing their anticodon with mRNA codons.

Genetic Code

The universal, non-overlapping, degenerate set of 64 mRNA codons that specify 20 amino acids or translation stop signals.

Codon

A sequence of three adjacent nucleotides in mRNA that codes for a single amino acid or a stop signal.

Reading Frame

One of three possible ways of grouping mRNA nucleotides into codons; only one is used for a given protein.

Start Codon (AUG)

The first codon recognized by the ribosome, coding for methionine and defining the reading frame of the ORF.

Stop Codon (UAA, UAG, UGA)

A codon that does not encode an amino acid but signals termination of translation.

Open Reading Frame (ORF)

The continuous stretch of codons beginning with a start codon and ending with a stop codon that is translated into protein.

5' UTR

Untranslated region upstream of the start codon that helps regulate translation initiation.

3' UTR

Untranslated region downstream of the stop codon that influences mRNA stability and translation efficiency.

5' Cap (m7Gppp)

Modified guanine nucleotide added to the 5' end of eukaryotic mRNA required for ribosome binding and translation initiation.

Poly(A) Tail

A stretch of adenine residues added to the 3' end of eukaryotic mRNA that enhances stability and translation.

Ribosome

A large ribonucleoprotein complex composed of small and large subunits that coordinates mRNA decoding and peptide-bond formation.

A Site (Aminoacyl Site)

Ribosomal site where incoming charged tRNA binds to the mRNA codon.

P Site (Peptidyl Site)

Ribosomal site that holds the tRNA carrying the growing polypeptide chain.

E Site (Exit Site)

Ribosomal site where deacylated (uncharged) tRNA temporarily resides before leaving the ribosome.

Peptidyltransferase

The ribosomal rRNA-based catalytic activity that forms peptide bonds between amino acids during elongation.

Aminoacyl-tRNA Synthetase

One of 20 enzymes that attach the correct amino acid to its corresponding tRNA, charging it for translation.

Charged tRNA

A tRNA molecule to which its specific amino acid has been covalently attached by an aminoacyl-tRNA synthetase.

Wobble Position

The 5' nucleotide of a tRNA anticodon that can form non-standard base pairs, allowing one tRNA to recognize multiple codons.

Initiator tRNA (tRNAi^Met)

Special methionine tRNA that starts translation by binding to the start codon in the P site of the small ribosomal subunit.

Translation Initiation Factors (eIFs)

Protein factors that assemble the small ribosomal subunit with mRNA and initiator tRNA and help locate the start codon.

Translation Elongation Factors (EF1, EF2)

GTP-binding proteins that deliver aminoacyl-tRNAs to the A site (EF1) and drive ribosome translocation (EF2).

Release Factors (eRF1, eRF3)

Proteins that recognize stop codons and trigger cleavage of the polypeptide from the tRNA, terminating translation.

Polysome (Polyribosome)

An mRNA molecule simultaneously being translated by multiple ribosomes, increasing protein synthesis efficiency.

eIF2 Phosphorylation

Regulatory modification that prevents eIF2 from exchanging GDP for GTP, thereby blocking translation initiation under stress.

Aminoglycoside Antibiotics

Prokaryote-specific drugs that bind to the small ribosomal subunit and disrupt decoding, inhibiting bacterial protein synthesis.

Wobble Base-Pair Rules

Set of permissible non-Watson–Crick pairings in the wobble position (e.g., G–U, I–A/C/U) that expand decoding capacity.