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Multiple choice question for engineering

Set 1

1. Bacteria have
a) 70S ribosomes
b) 60S ribosomes
c) 50S ribosomes
d) 80S ribosomes

View Answer

Answer: a [Reason:] Bacteria have 70S ribosomes, with a large (50S) and a small (30S) subunit.

2. Which of the following inactivates the 60S subunit of eukaryotic ribosomes?
a) Chloramphenicol
b) Cycloheximide
c) Diphtheria toxin
d) Ricin

View Answer

Answer: d [Reason:] Ricin inactivates the 60S subunit of eukaryotic ribosomes by depurinating a specific adenosine in 23S r-RNA.

3. Which is the third elongation step in bacteria?
a) Peptide bond formation
b) Binding of an incoming aminoacyl t-RNA
c) Translocation
d) None

View Answer

Answer: c [Reason:] Binding of an incoming aminoacyl t-RNA is the first step, peptide bond formation is the second step and translocation is the final elongation step in bacteria.

4. In how many steps protein biosynthesis takes place?
a) 2
b) 3
c) 4
d) 5

View Answer

Answer: d [Reason:] Activation of amino acids, initiation, elongation, termination and release and folding and posttranslational processing are the five steps.

5. The role of mRNA in protein synthesis is
a) It translates genetic code to a specific amino acid
b) It modifies mRNA molecules prior to protein synthesis
c) It provides genetic blueprint for the protein
d) It catalyzes the process

View Answer

Answer: c [Reason:] t-RNA translates genetic code to a specific amino acid. sn-RNA modifies mRNA molecules prior to protein synthesis. r-RNA catalyzes the process.

6. The role of small nuclear RNAs in protein synthesis is
a) It translates genetic code to a specific amino acid
b) It modifies mRNA molecules prior to protein synthesis
c) It provides genetic blueprint for the protein
d) It catalyzes the process

View Answer

Answer: b [Reason:] t-RNA translates genetic code to a specific amino acid. r-RNA catalyzes the process. mRNA provides genetic blueprint for the protein.

7. 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

View Answer

Answer: d [Reason:] The initiating (5’) AUG is guided to its correct position by the Shine Dalgarno sequence in the mRNA.

8. Which of the following blocks the peptidyl transferase of 80S eukaryotic ribosomes?
a) Chloramphenicol
b) Cycloheximide
c) Diphtheria toxin
d) Ricin

View Answer

Answer: b [Reason:] Chloramphenicol does not affect cytosolic protein synthesis in eukaryotes.

9. Which of the following catalyzes ADP-ribosylation of a diphthamide residue?
a) Chloramphenicol
b) Cycloheximide
c) Diphtheria toxin
d) Ricin

View Answer

Answer: c [Reason:] Diphtheria toxin catalyzes ADP-ribosylation of a diphthamide residue of eukaryotic elongation factor eEF2, thereby inactivating it.

10. Which of the following inhibits initiation at higher concentrations?
a) Chloramphenicol
b) Streptomycin
c) Diphtheria toxin
d) Ricin

View Answer

Answer: b [Reason:] Streptomycin, a basic tri-saccharide causes misreading of the genetic code at relatively low concentrations and inhibits initiation at higher concentrations.

Set 2

1. Posttranslational modification of many eukaryotic proteins begins in the
a) Endoplasmic reticulum
b) Mitochondria
c) Chloroplasts
d) Nucleus

View Answer

Answer: a [Reason:] Most lysosomal, membrane or secreted proteins have an amino-terminal signal sequence that marks them for translocation into the lumen of the ER.

2. The antibiotic aided in elucidating the steps of protein glycosylation is
a) Streptomycin
b) Tunicamycin
c) Penicillin
d) Chrocin

View Answer

Answer: b [Reason:] It acts by interfering with one or more steps in this process.

3. The coated pits are coated on their cytosolic side with a lattice of
a) Clathrin
b) Lipoprotein
c) Gycoprotein
d) Transferrin

View Answer

Answer: a [Reason:] Clathrin is coated on the cytosolic side of the coated pits.

4. How many amino acid residues are there in ubiquitin?
a) 72
b) 73
c) 75
d) 76

View Answer

Answer: d [Reason:] One of the most highly conserved proteins is known as ubiquitin (76 amino acid residues).

5. The two subassemblies of 26S proteasome are
a) 20S core particle and 19S regulatory particle
b) 20S regulatory particle and 19S core particle
c) 18S core particle and 19S regulatory particle
d) 20S core particle and 18S regulatory particle

View Answer

Answer: a [Reason:] The two subassemblies are 20S core particle and 19S regulatory particle.

6. Proteins tagged with mannose 6-phosphate are transported to
a) Golgi complex
b) Mitochondria
c) Lysosome
d) Nucleus

View Answer

Answer: c [Reason:] The presence of one or more mannose 6-phosphate residues in its N-linked oligosaccharide is the structural signal that targets the protein to lysosomes.

7. Signal sequences are
a) Short peptide sequences attached to a protein that initiates its degradation by digestive enzymes
b) Short peptide sequences to transport a protein to the nucleus
c) Glycoproteins that serve as an address for transporting newly synthesized protein to the correct location
d) Short peptide sequences that serves as an address for transporting newly synthesized proteins to the correct location

View Answer

Answer: d [Reason:] The signal sequence directs a protein to its appropriate location in the cell.

8. The correct order of transport of protein in a secretory pathway is
a) Protein synthesized in the cytoplasm-SER lumen-RER lumen-cis Golgi-median Golgi-trans Golgi-vesicles-fusion of vesicles with plasma membrane-exocytosis
b) Protein synthesized in the cytoplasm-RER lumen-cis Golgi-median Golgi-trans Golgi-vesicles-fusion of vesicles with plasma membrane-exocytosis
c) Protein synthesized in the cytoplasm- vesicles -SER lumen-RER lumen-cis Golgi-median Golgi-trans Golgi-fusion of vesicles with plasma membrane-exocytosis
d) Protein synthesized in the cytoplasm- RER lumen-trans Golgi -median Golgi-cis Golgi -vesicles-fusion of vesicles with plasma membrane-exocytosis

View Answer

Answer: b [Reason:] Protein synthesized in the cytoplasm-RER lumen-cis Golgi-median Golgi-trans Golgi-vesicles-fusion of vesicles with plasma membrane-exocytosis.

9. Nuclear localization signal is rich in
a) Tryptophan and histidine
b) Serine and threonine
c) Glutamine and asparagine
d) Lysine and arginine

View Answer

Answer: d [Reason:] Nuclear localization signal is rich in lysine and arginine.

10. Secretory proteins are synthesized by
a) Ribosomes on nuclear membrane
b) Ribosomes on endoplasmic reticulum
c) Free ribosomes
d) None of the mentioned

View Answer

Answer: b [Reason:] Ribosomes on endoplasmic reticulum synthesize secretory proteins.

Set 3

1. Which of the following statements is not correct?
a) Bacteria possess only one type of RNA polymerase
b) Attenuation is a regulatory process used by bacteria to control the initiation of transcription
c) Repressor binds to operator
d) Bacterial genes are polycistronic

View Answer

Answer: b [Reason:] Attenuation results in premature termination of transcription.

2. Which of the following bacterial operon is not controlled by attenuation?
a) Arabinose
b) Tryptophan
c) Leucine
d) Histidine

View Answer

Answer: a [Reason:] Arabinose is a carbohydrate.

3. Which of the following is the most appropriate definition of an operator?
a) A non-coding, regulatory DNA sequence that is bound by RNA polymerase
b) A non-coding, regulatory DNA sequence that is bound by a repressor protein
c) A DNA-binding protein that regulates gene expression
d) A cluster of genes that are regulated by a single promoter

View Answer

Answer: b [Reason:] A repressor binds to operator.

4. To which class of transcription factor do nuclear receptors belong?
a) Zinc finger proteins
b) Leucine zipper proteins
c) Helix-turn-helix proteins
d) Helix-loop-helix proteins

View Answer

Answer: a [Reason:] Nuclear receptors belong to zinc finger motif.

5. Which of the following statements about lac operon in e.coli is true?
a) Promoter is the binding site for the lac repressor
b) Operon is only switched on in the absence of lactose in the growth medium
c) β-galactosidase is only produced in large quantities when the lac repressor is bound to the operator
d) Lac operon mRNA is a polycistronic mRNA

View Answer

Answer: d [Reason:] Bacterial genes are polycistronic and genes in eukaryotes are monocistronic.

6. Which of the following statements regarding the regulation of trp operon expression by attenuation is correct?
a) Rapid translation of the leader peptide prevents completion of mRNA transcript
b) Rapid translation of the leader peptide allows completion of mRNA transcript
c) The leader peptide sequence encodes enzymes required for tryptophan synthesis
d) The leader peptide sequence contains no tryptophan residues

View Answer

Answer: a [Reason:] Attenuation results in premature termination of transcription.

7. Which of the following increases gene expression as much as 200-fold?
a) TATA box
b) Insulator
c) Enhancer
d) CAAT box

View Answer

Answer: c [Reason:] Only enhancers can increase gene expression as much as 200-fold.

8. The mechanism by which CBP activates transcription is
a) CBP has DNA methyl transferase activity
b) CBP has histone acetyl transferase activity
c) CBP interacts with the basal transcription complex
d) CBP interacts with the basal transcription complex and has histone acetyl transferase activity

View Answer

Answer: c [Reason:] CBP interacts with the basal transcription complex and activates transcription.

9. RNAi stands for
a) RNA inducer
b) RNA interference
c) RNA intron
d) RNA insertion

View Answer

Answer: b [Reason:] RNAi stands for RNA interference.

10. Which of the following about mRNA stability is not correct?
a) Regulation of mRNA stability is a way of regulating gene expression
b) Prokaryotic mRNAs have a half-life of only a few minutes
c) Histone mRNAs have especially long poly-A tails and are stable
d) It is thought that poly-A tails stabilize eukaryotic mRNAs

View Answer

Answer: c [Reason:] Histone mRNAs lack poly-A tails so they are unstable.

Set 4

1. An example of RNA-dependent DNA polymerase is
a) Reverse transcriptase
b) DNA ligase
c) RNA polymerase I
d) RNA polymerase II

View Answer

Answer: a [Reason:] RNA polymerase I, RNA polymerase II are DNA dependent RNA polymerases and DNA ligase is ATP-dependent.

2. Reverse transcriptase does not catalyze
a) RNA-dependent DNA synthesis
b) RNA degradation
c) DNA-dependent DNA synthesis
d) DNA-dependent RNA synthesis

View Answer

Answer: d [Reason:] Reverse transcriptase catalyzes three different reactions: RNA-dependent DNA synthesis, RNA degradation and DNA-dependent DNA synthesis.

3. Which of the following are not DNA viruses?
a) Hepatitis B virus
b) Influenza A virus
c) CMV virus
d) Parvovirus

View Answer

Answer: b [Reason:] Influenza A virus is RNA virus.

4. Which of the following statements about viruses is true?
a) They contain DNA
b) They contain RNA
c) They contain protein
d) They are susceptible to lipid solvents

View Answer

Answer: c [Reason:] They contain either DNA or RNA. Only enveloped viruses are susceptible to lipid solvents.

5. The enzyme used in the formation of cDNA from mRNA is
a) Polymerase
b) Helicase
c) Reverse transcriptase
d) Gyrase

View Answer

Answer: c [Reason:] Reverse transcriptases make possible the synthesis of DNA complementary to an mRNA template.

6. Which of the following solves the problem of shortening of chromosomes in each cell cycle?
a) DNA ligase
b) Endonuclease
c) Telomerase
d) RNA polymerase

View Answer

Answer: c [Reason:] Telomerase adds telomeres to chromosome ends and solve the problem of chromosomes shortening.

7. Which of the following is RNA-dependent RNA polymerase?
a) Reverse transcriptase
b) RNA polymerase I
c) RNA polymerase II
d) RNA replicase

View Answer

Answer: d [Reason:] RNA polymerase I, RNA polymerase II are DNA dependent RNA polymerases and reverse transcriptase is RNA-dependent DNA polymerase.

8. HIV may not respond to
a) Nucleoside analogues
b) Protease inhibitors
c) Neuraminidase inhibitors
d) Reverse transcriptase inhibitors

View Answer

Answer: c [Reason:] Neuraminidase inhibitors are used for the treatment of influenza virus.

9. Which of the following introns have self-splicing activity?
a) Group I and group II
b) Group II and group III
c) Group III and group IV
d) Group I and group III

View Answer

Answer: a [Reason:] Only group I and group II introns have self-splicing activity.

10. Which type of homing is DNA-based?
a) Group I intron
b) Group II intron
c) Group III intron
d) Group IV intron

View Answer

Answer: a [Reason:] Group II intron homing occurs through an RNA intermediate.

Set 5

1. Which of the following statements regarding splicing in eukaryotes is correct?
a) Several reactions in the splicing process involve hydrolysis of ATP
b) Exons are spliced out and introns are retained in the mature mRNA transcript
c) Splicing takes place in the cytosol
d) Small nuclear RNAs are retained in the mature mRNA transcript

View Answer

Answer: a [Reason:] Splicing takes place within the nucleus. Introns are spliced out and exons are retained in the mature mRNA transcript.

2. Which of the following is not involved in the post transcriptional processing of t-RNA?
a) Base modulation
b) Attachment of CCA arm
c) Splicing
d) Attachment of poly-A tail

View Answer

Answer: d [Reason:] Base modulation, attachment of CCA arm and splicing are involved in the post transcriptional processing of t-RNA.

3. Incorrect statement about m-RNA
a) Cap is added to the 5’ end
b) Introns are removed and exons are spliced together
c) Histone mRNAs lack 5’ cap
d) Poly-A tail is added to the 3’ end

View Answer

Answer: b [Reason:] Introns are removed and exons are ligated.

4. The first nucleic acid synthesizing enzyme discovered is
a) Polynucleotide phosphorylase
b) DNA polymerase
c) RNA polymerase
d) DNA ligase

View Answer

Answer: a [Reason:] Polynucleotide phosphorylase is the first nucleic acid synthesizing enzyme discovered.

5. 70S prokaryotic ribosome is the complex of
a) 30S + 50S
b) 30S + 40S
c) 20S + 60S
d) 20S + 30S

View Answer

Answer: a [Reason:] 70S prokaryotic ribosome is the complex of 30S and 50S subunits.

6. 80S eukaryotic ribosome is the complex of
a) 60S and 40S
b) 40S and 20S
c) 60S and 50S
d) 30S and 20S

View Answer

Answer: a [Reason:] 80S eukaryotic ribosome is the complex of 60S and 40S subunits.

7. The main function of t-RNA is
a) Proof reading
b) Inhibits protein synthesis
c) Identifies amino acids and transport them to ribosomes
d) None

View Answer

Answer: c [Reason:] t-RNA identifies amino acids and transports them to ribosomes.

8. One of the following best describes the cap modification of eukaryotic mRNA
a) Modified guanine nucleotide added to the 3’ end of the transcript
b) Modified guanine nucleotide added to the 5’ end of the transcript
c) String of adenine nucleotides added to the 3’ end of the transcript
d) String of adenine nucleotides added to the 5’ end of the transcript

View Answer

Answer: b [Reason:] Modified guanine nucleotide added to the 5’ end of the transcript, this best describes the cap modification of eukaryotic mRNA.

9. The largest class of introns which are found in nuclear mRNA primary transcript is
a) Spliceosomal introns
b) Group I introns
c) Group II introns
d) Group IV introns

View Answer

Answer: a [Reason:] Spliceosomal introns are the largest class of introns which are found in nuclear mRNA primary transcript.

10. Which type of splicing reaction requires a guanine nucleoside or nucleotide cofactor that is not used as a source of energy?
a) Spliceosomal
b) Group I
c) Group II
d) Group IV

View Answer

Answer: b [Reason:] Group I type of splicing reaction requires a guanine nucleoside or nucleotide cofactor that is not used as a source of energy.