Cell And Molecular Biology

80 Questions | By Bensale_28 | Updated: Mar 21, 2022 | Attempts: 416

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Cell and Molecular Biology

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1.

What covalent bonds link nucleic acid monomers?
- A.
  
  Hydrogen bonds
- B.
  
  Carbon-Nitrogen bond
- C.
  
  Oxygen-Nitrogen Bond
- D.
  
  Phosphodiester bonds
- E.
  
  Carbon-Carbon double bonds
2.

The figure below shows two possible conformations of DNA, numbered 1 and 2. Of these, figure 2 indicates which one of the following DNA conformations
- A.
  
  C-DNA
- B.
  
  B-DNA
- C.
  
  N-DNA
- D.
  
  Z-DNA
- E.
  
  A-DNA
3.

Which of the following scientists first discovered that the percentage of GC is constant in any given species
- A.
  
  Hershey and Chase
- B.
  
  Frederick Miescher
- C.
  
  Erwin Chargaff
- D.
  
  Avery, McCleod and McCarty
- E.
  
  Frederick Griffiths
4.

Small nucleolar RNAs are involved in which one of the following functions
- A.
  
  MRNA splicing
- B.
  
  TRNA synthesis
- C.
  
  RRNA modification and processing
- D.
  
  Telomere synthesis
- E.
  
  MRNA binding
5.

The ability of DNA to denature is important for which process?
- A.
  
  All of the options
- B.
  
  Nucleic acid hybridization experiments
- C.
  
  Polymerase Chain Reaction
- D.
  
  DNA synthesis
- E.
  
  RNA synthesis
6.

DNA replication begins at sequences called :
- A.
  
  Start
- B.
  
  Rep
- C.
  
  Lga
- D.
  
  Ori
- E.
  
  Aug
7.

F a mutation occurs in a cell preventing the double-stranded DNA strands from separating at the replication fork, then the gene for which enzyme would you predict was altered by this mutation?
- A.
  
  DNA ligase
- B.
  
  DNA polymerase
- C.
  
  RNA primase
- D.
  
  SsDNA binding protein
- E.
  
  DNA helicase
8.

The base in the wobble position of a codon
- A.
  
  Is the 3´ (third) base.
- B.
  
  is the 5´ (first) base.
- C.
  
  Often contains adenine.
- D.
  
  Is the second base
- E.
  
  Often contains thymine
9.

Which of the following factors recognizes and binds to the UAG, UAA, and UGA codons?
- A.
  
  RNA polymerase
- B.
  
  RNA synthase
- C.
  
  DNA polymerase
- D.
  
  Termination factors
- E.
  
  Elongation factors
10.

Which of the following are removed from mRNAs during processing?
- A.
  
  Exons
- B.
  
  RNA cap structure
- C.
  
  Introns
- D.
  
  RNA polymerase
- E.
  
  poly(A) tail
11.

The radionuclide phosphorus-32 (32P) has a half-life of:
- A.
  
  59.6 days
- B.
  
  5,760 years
- C.
  
  12.4 years
- D.
  
  14.3 days
- E.
  
  87.4 days
12.

When preparing DNA from E. coli contaminating protein can be removed via:
- A.
  
  Harvesting the cells at late exponential phase
- B.
  
  Phenol extraction
- C.
  
  Ethanol precipitation
- D.
  
  Grinding in liquid nitrogen
- E.
  
  Ethidium bromide precipitation
13.

Messenger RNA (mRNA) makes up about 1% of the total cellular RNA. What feature of mRNA enables it to be selectively purified?
- A.
  
  It can be copied by reverse transcriptase into DNA
- B.
  
  Its clover-leaf secondary structure
- C.
  
  It is single stranded
- D.
  
  It lacks introns
- E.
  
  It is polyadenylated
14.

Agarose gels are used to separate DNA fragments according to size. During electrophoresis DNA moves:
- A.
  
  By gravity
- B.
  
  From the anode towards the cathode
- C.
  
  By gel filtration
- D.
  
  From the cathode towards the anode
- E.
  
  By capillary action
15.

After electrophoresis, agarose gels containing DNA fragments are stained with ethidium bromide and placed on an ultra-violet transilluminator, which permits the detection of small amounts of DNA. What is the lowest amount of DNA detectable by this method?
- A.
  
  10 ng
- B.
  
  10 mg
- C.
  
  10 μg
- D.
  
  10 pg
- E.
  
  10 fg
16.

Plasmid cloning vectors often contain an antibiotic resistance gene that acts as a selectable marker. When grown in the presence of the antibiotic this resistance gene enables you to
- A.
  
  Select for β-gal-plus E. coli cells
- B.
  
  Select for E. coli cells containing non-recombinant plasmids
- C.
  
  Select for β-gal-minus E. coli cells
- D.
  
  Select for E. coli cells containing plasmids
- E.
  
  Select for E. coli cells containing recombinant plasmids
17.

Which of these refers specifically to the artificial introduction of naked bacteriophage DNA into bacteria?
- A.
  
  Induction
- B.
  
  Infection
- C.
  
  Transformation
- D.
  
  Transduction
- E.
  
  Transfection
18.

Bacteriophage lambda has two alternative life cycles. One of these is of use to the genetic engineer in lambda-derived cloning vectors. This life cycle is called:
- A.
  
  Lytic
- B.
  
  Late
- C.
  
  Lysogenic
- D.
  
  Rolling circle
- E.
  
  Logarithmic
19.

In a replacement vector a single “stuffer” fragment serves to replace all the “non-essential” regions removed from the lambda genome. The “stuffer” fragment is necessary:
- A.
  
  Because it contains essential genes
- B.
  
  To enable the vector to be replicated
- C.
  
  Because it contains the cos ends
- D.
  
  Because it is recognised by the packaging mix
- E.
  
  T enables recombinant clones to be identified
20.

When constructing a genomic library in a replacement vector the genomic DNA is partially digested with a restriction enzyme, such as Sau 3A, that recognises a four nucleotide sequence. This is to:
- A.
  
  Ensure that restriction fragments of between 15 – 22 kilo base pairs can contain all the genome of the organism
- B.
  
  Ensure that the restriction fragments have a mean size of 4096 base pairs
- C.
  
  Ensure that the restriction fragments have a mean size of 256 base pairs
- D.
  
  Ensure that all restriction fragments are of a size that are clonable
- E.
  
  Ensure that there are no restriction fragments below 256 base pairs in size
21.

The DNA probe used in nucleic acid hybridisation is often labelled by incorporating a radioactive nucleotide, such as 32P-labelled deoxycytosine 5’ triphosphate (dCTP) using the Klenow fragment of DNA polymerase. Which phosphate is labelled:
- A.
  
  Beta (β)
- B.
  
  Epsilon (ε)
- C.
  
  Delta (δ)
- D.
  
  Alpha (α)
- E.
  
  Gamma (γ)
22.

The double-stranded products of PCR are difficult to clone into conventional vectors cut with restriction enzymes, as Taq polymerase adds an extra nucleotide to either end. Therefore, you have to perform T/A cloning using special vectors possessing an extra complementary nucleotide. The extra nucleotide added to the PCR product by Taq is a:
- A.
  
  None of the options
- B.
  
  “T” to the 5’ ends
- C.
  
  A” to the 3’ ends
- D.
  
  T” to the 3’ ends
- E.
  
  A” to the 5’ ends
23.

Restriction fragment length polymorphisms (RFLPs) are detected by hybridising Southern blots of electrophoresed restriction digests with a labelled probe, and can be used for a variety of purposes from detecting genetic diseases to population genetics. RFLPs are:
- A.
  
  Variations in the lengths of restriction fragments
- B.
  
  Size-fractionated restriction fragments
- C.
  
  Variations in the shapes of restriction fragments
- D.
  
  Restriction maps of genomes
- E.
  
  Restriction maps of plasmids
24.

Which of the following is NOT an example of a reporter gene:
- A.
  
  Luciferase
- B.
  
  Blue fluorescent protein
- C.
  
  β-glucuronidase
- D.
  
  Green fluorescent protein
- E.
  
  β-glucosidase
25.

Proteins of interest can be expressed in microorganisms using special plasmids that contain promoters that can be induced or repressed (switched on or off) by external factors. The Trp promoter is an example of one of these. It is:
- A.
  
  Repressed by 3-β-indoleacrylic acid and induced by tryptophan
- B.
  
  Induced by 3-β-indoleacrylic acid and repressed by tryptophan
- C.
  
  Repressed by IPTG and induced by tryptophan
- D.
  
  Induced by IPTG and repressed by tryptophan
- E.
  
  None of the options