Translation and Protein Synthesis Practice Questions
20 free Translation and Protein Synthesis practice questions for the Zoology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Translation is the process by which:
- A DNA is copied into RNA
- B RNA is converted into protein
- C Proteins are modified after synthesis
- D Amino acids are synthesized
Correct answer: RNA is converted into protein
Translation converts the nucleotide sequence of mRNA into a polypeptide chain. It occurs on ribosomes using tRNA and amino acids.
The site of translation in a cell is the:
- A Nucleus
- B Golgi apparatus
- C Ribosome
- D Endoplasmic reticulum only
Correct answer: Ribosome
Translation occurs on ribosomes present in the cytoplasm or on the rough endoplasmic reticulum. Ribosomes provide the platform for protein synthesis.
The initiation codon for translation is:
- A UAA
- B UGA
- C AUG
- D UAG
Correct answer: AUG
AUG serves as the initiation codon and codes for methionine. It signals the start of translation.
During translation initiation in prokaryotes, the small ribosomal subunit binds to the:
- A Poly-A tail
- B Shine-Dalgarno sequence
- C Start codon directly
- D Termination codon
Correct answer: Shine-Dalgarno sequence
The Shine-Dalgarno sequence aligns the mRNA with the ribosome. This ensures correct positioning of the start codon.
Which RNA molecule brings amino acids to the ribosome?
- A Poly-A tail at the 3' end
- B Shine-Dalgarno sequence
- C The start codon directly, without upstream help
- D The termination codon region
Correct answer: Shine-Dalgarno sequence
The Shine-Dalgarno sequence aligns the mRNA with the ribosome by base-pairing with 16S rRNA in the small subunit. This ensures correct positioning of the start codon at the P site.
The ribosomal site that holds the growing polypeptide chain is the:
- A A site
- B P site
- C E site
- D S site
Correct answer: P site
The P site holds the tRNA carrying the growing polypeptide chain. Peptide bond formation occurs between amino acids at the P and A sites.
During elongation, peptide bonds are formed by the activity of:
- A Aminoacyl-tRNA synthetase
- B Peptidyl transferase
- C Release factor
- D Initiation factor
Correct answer: Peptidyl transferase
Peptidyl transferase catalyzes peptide bond formation between the growing chain and the incoming amino acid. It is a ribozyme activity carried out by the 23S rRNA in the large ribosomal subunit.
Which ribosomal site is responsible for entry of aminoacyl-tRNA?
- A P site
- B E site
- C A site
- D R site
Correct answer: A site
The A site binds incoming aminoacyl-tRNA during elongation. Correct codon-anticodon pairing occurs here.
The E site of the ribosome functions to:
- A Bind incoming tRNA
- B Hold the growing polypeptide
- C Release empty tRNA
- D Bind mRNA
Correct answer: Release empty tRNA
The E site releases tRNA after it has transferred its amino acid. This allows the ribosome to continue elongation.
Elongation of the polypeptide chain proceeds in which direction?
- A C-terminus to N-terminus
- B N-terminus to C-terminus
- C Random direction
- D Both directions simultaneously
Correct answer: N-terminus to C-terminus
Polypeptides are synthesized from the N-terminus to the C-terminus. Each new amino acid is added to the carboxyl end.
Translocation during elongation moves the ribosome along mRNA by:
- A One nucleotide at a time
- B Two nucleotides at a time
- C Three nucleotides at a time
- D Six nucleotides at a time
Correct answer: Three nucleotides at a time
The ribosome moves exactly three nucleotides (one codon) at a time during translocation, powered by GTP hydrolysis of EF-G (EF-2 in eukaryotes). Each shift exposes the next codon at the A site.
Which factor provides energy for translocation during elongation?
- A ATP
- B cAMP
- C GTP
- D NADH
Correct answer: GTP
GTP hydrolysis provides energy for ribosomal movement during translocation. Elongation factors facilitate this process.
Termination of translation occurs when the ribosome encounters:
- A A start codon (AUG)
- B A sense codon for an amino acid
- C A stop codon (UAA, UAG, or UGA)
- D A Shine-Dalgarno sequence
Correct answer: A stop codon (UAA, UAG, or UGA)
Stop codons (UAA, UAG, and UGA) signal the end of translation. They are not recognized by any tRNA and do not code for an amino acid; instead, release factors bind and trigger polypeptide release.
Which of the following is a stop codon?
- A AUG
- B UAC
- C UAA
- D GUG
Correct answer: UAA
UAA is one of the three stop codons. Stop codons terminate protein synthesis.
Release factors function during translation to:
- A Bring amino acids to the ribosome
- B Catalyze peptide bond formation
- C Recognize stop codons in the A site
- D Initiate translation at the start codon
Correct answer: Recognize stop codons in the A site
Release factors bind to stop codons at the A site. They promote hydrolysis of the peptidyl-tRNA bond, releasing the completed polypeptide and triggering ribosome disassembly.
Which molecule is released at the end of translation?
- A mRNA template strand
- B tRNA with its anticodon
- C Polypeptide chain
- D rRNA scaffold complex
Correct answer: Polypeptide chain
The completed polypeptide chain is released during termination when a release factor triggers hydrolysis of the bond between the polypeptide and the final tRNA. The ribosomal subunits then dissociate for reuse.
In eukaryotes, translation initiation requires recognition of the:
- A Shine-Dalgarno sequence
- B Poly-A tail
- C 5' cap structure
- D Termination codon
Correct answer: 5' cap structure
The 5' cap is essential for eukaryotic translation initiation. It helps recruit the ribosomal subunits.
Which amino acid is the first incorporated during eukaryotic translation?
- A Methionine
- B Formylmethionine
- C Alanine
- D Glycine
Correct answer: Methionine
Eukaryotic translation begins with methionine. Prokaryotes use a modified form, formylmethionine.
Polysomes are structures formed when:
- A Multiple ribosomes simultaneously translate one mRNA
- B Multiple mRNA molecules bind to one ribosome
- C Ribosomes aggregate together in the absence of mRNA
- D Individual ribosomes stall and halt translation
Correct answer: Multiple ribosomes simultaneously translate one mRNA
Polysomes consist of several ribosomes translating the same mRNA simultaneously, increasing the efficiency of protein synthesis. Each ribosome is at a different stage of elongation along the transcript.
A key difference between prokaryotic and eukaryotic translation is that prokaryotes:
- A Use an entirely different genetic code
- B Carry out translation exclusively in the nucleus
- C Couple transcription and translation simultaneously
- D Synthesize proteins without ribosomes
Correct answer: Couple transcription and translation simultaneously
In prokaryotes, transcription and translation occur simultaneously in the cytoplasm because there is no nuclear membrane separating the two processes. Eukaryotes must export mRNA to the cytoplasm before translation begins.