Protein Synthesis MCQs : This section focuses on the "Protein Synthesis". These Multiple Choice Questions (MCQs) should be practiced to improve the Protein Synthesis skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
Question 1
Protein synthesis rates in prokaryotes are limited by the rate of mRNA synthesis. If RNA synthesis occurs at the rate of 50 nucleotides/sec, then rate of protein synthesis occurs at
A. 10 amino acids/sec
B. 17 amino acids/sec
C. 25 amino acids/sec
D. 50 amino acids/sec
Question 2
Translation in prokaryotes begins by the formation of a 30S initiation complex between the
A. 30S ribosomal subunit, mRNA, initiation factors and N-fMet tRNA
B. 30S ribosomal subunit, tRNA and initiation factors
C. 30S ribosomal subunit and mRNA only
D. 30S ribosomal subunit, mRNA and initiation factors
Question 3
Proteins contain __________ different amino acids, whereas DNA and RNA are composed of __________ different nucleotides
A. 20,64
B. 3,20
C. 4,20
D. 20,4
Question 4
The structure in a bacterium that indicates an active site for protein synthesis is
A. a chromosome.
B. a cell membrane,
C. a flagellum.
D. a polysome.
Question 5
The pathway of a tRNA during polypeptide elongation on the ribosome is
A. A site → P site → E site
B. P site → entry site → exit site
C. A site → P site → entry site
D. P site → A site → E site
Question 6
The site on a bacterial chromosome that marks the termination point for chromosome replication is called
A. ter
B. a stop codon.
C. a stem-loop
D. pau
Question 7
Which site of the tRNA molecule binds to the mRNA molecule?
A. Anticodon
B. Codon
C. Amino acid
D. 5 prime end
Question 8
A polysome could be best described as
A. an active site of DNA synthesis.
B. an active site of protein synthesis.
C. an active site of lipid synthesis.
D. all of the above.
Question 9
The peptidyl transferase reaction occurs
A. on the large subunit
B. on the small subunit
C. between the subunit
D. none of these
Question 10
The first step in translation is
A. binding of the two ribosomal subunits to each other
B. binding of mRNA to the two ribosomal subunits
C. binding of tRNA to the small ribosomal subunit
D. binding of mRNA to the small ribosomal subunit
Question 11
The anticodon of tRNA
A. binds to rRNA
B. binds to an amino acid
C. binds to the Shine Dalgarno sequence
D. binds to an mRNA codon
Question 12
The ribosomes are composed of
A. proteins
B. RNA
C. both (a) and (b)
D. lipids
Question 13
Ribosomes select the correct tRNAs
A. then bind to the appropriate mRNA
B. solely on the basis of their anticodons
C. depending on their abundance in the cytosol
D. with the least abundant anticodons
Question 14
The lac operon contains the z, y and a structural genes
A. encoding p-galactosidase, galactose permeases and thio-galactosidase transacetylase respectively
B. encoding p-galactosidase and galactose permeases
C. encoding P-galactosidase only
D. None of the above
Question 15
The site of protein synthesis is
A. Ribosome
B. Nucleus
C. Endoplasmic reticulum
D. Chromosome
Question 16
The direction of amino acid transfer to the growing polypeptide chain is
A. from the A (aminoacyl tRNA site) site to the P (peptidyl tRNA site) site on the ribosome
B. from the P site to the A site on the ribosome
C. from the A site to the E (exit tRNA site) site on the ribosome
D. from the P site to the E site on the ribosome
Question 17
Amino acids are joined together into a protein chain by which of the following?
A. Transfer RNA
B. DNA polymerase
C. Hydrogen bonds
D. Messenger RNA
Question 18
Which of the following is not a necessary component of translation?
A. Anticodon
B. mRNA
C. Ligase
D. Amino acid
Question 19
Phosphorus is taken up by the cell during the process of
A. carbohydrate synthesis.
B. protein synthesis,
C. lipid synthesis.
D. ATP synthesis.
Question 20
Which of the following is not necessary for protein synthesis to occur, once transcription is completed?
A. tRNA
B. Ribosomes
C. mRNA
D. DNA
Question 21
Type I proteins (plasma membrane) have a
A. cleavage N- terminal signal sequence and a hydrophobic stop transfer sequence
B. cleavaged N- terminal signal sequence that doubles as the membrane anchoring sequence
C. multiple signal sequence and a hydrophobic stop transfer sequence
D. multiple signal sequence that doubles as the membrane anchoring sequence
Question 22
Processive synthesis is a characteristic feature of
A. all DNA polymerases.
B. DNA Pol III at a replication fork.
C. removal of RNA primers on Okasaki fragments.
D. DNA mismatch repair
Question 23
Which of the following has unusual bases?
A. mRNA
B. tRNA
C. rRNA
D. hnRNA
Question 24
Which of the following RNAs bind to an amino acid?
A. mRNA
B. tRNA
C. rRNA
D. hnRNA
Question 25
Which is required for protein synthesis?
A. tRNA
B. mRNA
C. rRNA
D. All of these
Question 26
Signal peptide protein removal that is translocated across a membrane is accomplished by
A. fMet aminopeptidase
B. trypsin
C. signal peptidase
D. chymotrypsin
Question 27
The growing polypeptide chain is released from the ribosomes when
A. a chain terminating codon is reached
B. a chain terminating tRNA binds to the ribosome
C. the 7-methyl guanosine cap is reached
D. the poly A tail is reached
Question 28
Degenerated codon differs mostly in
A. the identities of their second base
B. the identities of their third base
C. the wobble position
D. both (b) and (c)
Question 29
Which of the following amino acid starts all proteins synthesis?
A. Glycine
B. Proline
C. Thymine
D. Methionine
Question 30
On the ribosome, mRNA binds
A. between the subunits
B. to the large subunit
C. to the small subunit
D. none of these
Question 31
Eukaryotic mRNA binding to the ribosomes is facilitated by __________ .
A. the Shine Dalgarno sequence
B. the 7-methyl guanosine cap
C. tRNA
D. poly A tail
Question 32
How many bases of nucleic acid determine a single amino acid?
A. Four
B. One
C. Two
D. Three
Question 33
Bacteria have ____________
A. 70S ribosomes
B. 60S ribosomes
C. 50S ribosomes
D. 80S ribosomes
Question 34
In how many steps protein biosynthesis takes place?
A. 2
B. 3
C. 4
D. 5
Question 35
The eukaryotic mRNA binding to the ribosomes is facilitated by ____________
A. T-RNA
B. Poly-A tail
C. Shine Dalgarno sequence
D. 7-methyl guanosine cap
Question 36
What is the role of mRNA in protein synthesis?
A. It translates genetic code to a specific amino acid
B. It modifies mRNA molecules prior to protein synthesis
C. It provides a genetic blueprint for the protein
D. It catalyzes the process
Question 37
What is the role of small nuclear RNAs in protein synthesis?
A. It translates genetic code to a specific amino acid
B. It modifies mRNA molecules prior to protein synthesis
C. It provides a genetic blueprint for the protein
D. It catalyzes the process
Question 38
Which is the third elongation step in bacteria?
A. Peptide bond formation
B. Binding of an incoming aminoacyl t-RNA
C. Translocation
D. None of the mentioned
Question 39
Which of the following blocks the peptidyl transferase of 80S eukaryotic ribosomes?
A. Chloramphenicol
B. Cycloheximide
C. Diphtheria toxin
D. Ricin
Question 40
Which of the following catalyzes ADP-ribosylation of a diphthamide residue?
A. Chloramphenicol
B. Cycloheximide
C. Diphtheria toxin
D. Ricin
Question 41
Which of the following inactivates the 60S subunit of eukaryotic ribosomes?
A. Chloramphenicol
B. Cycloheximide
C. Diphtheria toxin
D. Ricin
Question 42
Which of the following inhibits initiation at higher concentrations?
A. Chloramphenicol
B. Streptomycin
C. Diphtheria toxin
D. Ricin
Question 43
Conversion of messages carried by mRNA into amino acid sequences is called___________
A. Replication
B. DNA repair
C. Translation
D. Transcription
Question 44
Mark the one, which is NOT a stop codon?
A. UAA
B. UAG
C. UGA
D. GGA
Question 45
Name the drug which inhibits the initiation step of translation.
A. Cyclohexamine
B. Tetracycline
C. Ricin
D. Streptomycin
Question 46
Name the inhibitor which blocks translation in both prokaryotes as well as eukaryotes?
A. Chlorophenicol
B. Tetracycline
C. Puromycin
D. Streptomycin
Question 47
Name the sequence of RNA, which is recognized by a small subunit of the ribosome.
A. Rho utilization site
B. Downstream sequence
C. Upstream sequence
D. Shine Dalgarno sequence
Question 48
The following set of RNA is required in the translation process except one, mark the INCORRECT?
A. Si RNA
B. rRNA
C. mRNA
D. tRNA
Question 49
tRNA has peptidal transferase activity.
A. True
B. False
Question 50
What is the size of the prokaryotic ribosome?
A. 80S
B. 70S
C. 40S
D. 60S
Question 51
Which of the following inhibitor block translation in eukaryotes?
A. Cyclohexamine
B. Tetracycline
C. Puromycin
D. Streptomycin
Question 52
Which of the following is considered as a start codon?
A. AUG
B. GUG
C. UAG
D. AGG
Question 53
Which of the following is not true to the nature of the genetic code?
A. Codon is triplet
B. Codons are commaless
C. Codons are overlapping
D. Codons are universal
Question 54
Which of the following recognize a specific amino acid and its cognate t-RNA molecule?
A. t-RNA synthetase
B. Ribososme
C. r-RNA
D. Topoisomerase
Question 55
Who explained the wobble hypothesis?
A. Darwin
B. Watson and Crick
C. Samuel B. Weiss
D. Nirenberg