Cell And Molecular Biology

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Cell And Molecular Biology

Cell and Molecular Biology


Questions and Answers
  • 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. 
    • 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

  • 26. 
    Which of the following enzymes will produce a blunt end (the cut site is indicated by the * in the recognition sequence)?
    • A. 

      AluI (AG*CT)

    • B. 

      BamHI (G*GATCC)

    • C. 

      EcoRI (G*AATTC)

    • D. 

      Sau3A (*GATC)

  • 27. 
    Which of the following is a functional element of a plasmid?
    • A. 

      Origin of replication

    • B. 

      Polylinker sequence

    • C. 

      Drug-resistance gene

    • D. 

      All of the options

  • 28. 
    A DNA sequencing reaction contains which of the following?
    • A. 

      Dideoxyribonucleoside triphosphates

    • B. 

      deoxyribonucleoside triphosphates

    • C. 

      DNA polymerase

    • D. 

      All of the options

  • 29. 
    Southern blotting is used to detect a specific
    • A. 

      RNA.

    • B. 

      Carbohydrate

    • C. 

      DNA.

    • D. 

      Protein

  • 30. 
    CDNA libraries can be constructed in the insertion vector λgt11.  In which case an antibody can be used to identify your clone of interest through binding to a:
    • A. 

      Hybrid protein

    • B. 

      Fusion protein

    • C. 

      Accessory protein

    • D. 

      Fission protein

  • 31. 
    Reporter genes are a powerful tool used in gene expression studies because they provide the investigator with information pertaining to
    • A. 

      The cellular and tissue-specific localization of the mRNA encoded by a particular gene.

    • B. 

      The activity of the protein translated from a particular mRNA.

    • C. 

      The size of the mRNA transcript.

    • D. 

      All of the above

  • 32. 
    Deletion analysis is used to identify DNA sequence motifs in the regulatory region of a gene that modulate gene expression.  The proteins that interact with these motifs are called:
    • A. 

      Expression factors

    • B. 

      Accessory factors

    • C. 

      Control factors

    • D. 

      Transcription factors

  • 33. 
    High-value proteins can be produced in animals and plants by “pharming”.  In mammals such proteins are often driven by the following promoter of the following gene:
    • A. 

      α-haemoglobin

    • B. 

      α-lactoglobin

    • C. 

      β-haemoglobin

    • D. 

      β-lactoglobin

  • 34. 
    What method can be used to functionally inactivate a gene without altering its sequence?
    • A. 

      RNA interference and gene knockout

    • B. 

      RNA interference and anti-sense gene construct

    • C. 

      Anti-sense gene construct and gene knockout

    • D. 

      None of the options listed

  • 35. 
    According to the medium estimate of the United Nations the world’s population will peak in 2075 at: 
    • A. 

      10.3 billion

    • B. 

      9.2 billion

    • C. 

      7.8 billion

    • D. 

      9.5 billion

    • E. 

      8.4 billion

    • F. 

      15.6 billion

  • 36. 
    The development of higher animals and higher plants differ in several significant ways. Select appropriate answers from the list below: 
    • A. 

      Plant development is accomplished by varying the plane of cell division only

    • B. 

      Plant cells move and migrate during embryonic development

    • C. 

      Animal development is mostly post-embryonic

    • D. 

      Higher plant embryos do not contain organs found in the adult

    • E. 

      Plants can regenerate from numerous vegetative (somatic) parts

  • 37. 
    Arabidopsis thaliana is a plant used by scientists as a model organism.  Which of the following is NOT a feature of this plant?
    • A. 

      Self-fertilisation

    • B. 

      A diploid genome consisting of 10 chromosomes

    • C. 

      A genome containing 7,000 fewer genes than the human genome

    • D. 

      A rapid life cycle of approximately 10 weeks under laboratory conditions

    • E. 

      All of the options are true

  • 38. 
    What happens in an apetala 3 null mutant flower? 
    • A. 

      Whorl 1 organs are carpels

    • B. 

      Whorl 2 organs are sepals and whorl 3 organs are carpels

    • C. 

      Whorl 2 organs are petals and whorl 3 organs are stamens

    • D. 

      Whorl 3 organs are stamens and whorl 3 organs are carpels

  • 39. 
    The ABC model for flower development in Arabidopsis has 2 key features. Which of the following is correct?:
    • A. 

      All ABC homeotic genes encode MADS box proteins. All ABC homeotic genes are regulated at the level of transcription.

    • B. 

      Based on mutations that define 3 ABC homeotic genes. All ABC homeotic genes are regulated at the level of transcription.

    • C. 

      ABC homeotic genes operate in 4 overlapping fields. Mutations in ABC homeotic genes affect pairs of overlapping whorls.

    • D. 

      Requires a combination of ABC homeotic genes expression to select the appropriate organ type. Regulatory antagonism exists between some ABC homeotic genes

    • E. 

      All ABC homeotic genes encode bHLH box proteins. All ABC homeotic genes are regulated at the level of transcription

  • 40. 
    The developing mammalian embryo divides by 
    • A. 

      Meroblastic cleavag

    • B. 

      Superficial cleavage

    • C. 

      Radial cleavage

    • D. 

      Equatorial cleavage

    • E. 

      Rotational cleavage

  • 41. 
    The endodermal germ layer will eventually form: 
    • A. 

      Epidermis, neurons of the brain and central nervous system, pigment cells

    • B. 

      Lining of the digestive tube, lining of the respiratory tube, thyroid cells

    • C. 

      Lining of the digestive tube, lining of the respiratory tube, pigment cells

    • D. 

      Epidermis, neurons of the brain and central nervous system, peripheral nervous system

    • E. 

      Muscle and connective tissues, bone, kidneys and gonads

  • 42. 
    During mammalian neurulation, neural folds form on the ectodermal layer of the trilaminar embryo, either side of the midline. The following processes then occur:
    • A. 

      Invagination occurs and a neural tube forms.

    • B. 

      Uncaught Exception.Please try to submit again.

    • C. 

      Ingression occurs and a neural tube forms.

    • D. 

      Ingression occurs and a notochord forms.

    • E. 

      Invagination occurs and a notochord forms.

  • 43. 
    What happens in a Ubx null mutant Drosophila fly? 
    • A. 

      Extra pair of wings and extra pair of halters

    • B. 

      Antennea where legs should be

    • C. 

      Extra pair of wings and loss of halteres

    • D. 

      Extra pair of legs and loss of halteres

    • E. 

      Loss of a pair of legs

  • 44. 
    In comparison to Drosophila, how many HOX genes do mammals have? 
    • A. 

      Four times as many as Drosophila

    • B. 

      Over four times as many as Drosophila.

    • C. 

      The same number as Drosophila

    • D. 

      Fewer than Drosophila

    • E. 

      Two times as many as Drosophila

  • 45. 
    What is the effect of UV irradiation on developing Xenopus leavisembryos? 
    • A. 

      inhibits left/right axis formation

    • B. 

      Inhibits ventral structures

    • C. 

      Inhibits anterior structures

    • D. 

      Inhibits posterior structures

    • E. 

      Inhibits dorsal structures

  • 46. 
    How big is the nuclear genome? 
    • A. 

      16.6 Mbp

    • B. 

      3.2 Mbp

    • C. 

      3.2 Gbp

    • D. 

      16.6kbp

  • 47. 
    How many genes does the human genome contain?
    • A. 

      26-32,000

    • B. 

      Over 50,000

    • C. 

      10-20,000

    • D. 

      5,000-10,000

    • E. 

      None of the above

  • 48. 
    What is the percentage of human variation?
    • A. 

      2.4%

    • B. 

      10%

    • C. 

      0.01%

    • D. 

      1.5%

    • E. 

      0.1%

  • 49. 
    What is the C value? 
    • A. 

      The total number of Cytosine Bases in an organism

    • B. 

      The total DNA content of an organism

    • C. 

      The number of Cytosine bases per haploid cell

    • D. 

      The DNA content of a haploid cell

    • E. 

      The number of chromosomes per haploid cell

  • 50. 
    How big is the largest known mammalian gene? 
    • A. 

      1.5 kbp

    • B. 

      5 Mbp

    • C. 

      6 kbp

    • D. 

      2.5 kbp

    • E. 

      2.5 Mbp

  • 51. 
    Why does a plasmid that has never been cut give more than one band on a gel?
    • A. 

      Junk DNA

    • B. 

      DNA Supercoiling

    • C. 

      Single stranded DNA

    • D. 

      SiRNA

  • 52. 
    There are two forms of DNA super coiling, which of the two involve histones? 
    • A. 

      Histone supercoiling

    • B. 

      Bacterial supercoiling

    • C. 

      Toroidal supercoiling

    • D. 

      Interwound supercoiling

  • 53. 
    In order to unwind supercoiled DNA which enzyme is used?
    • A. 

      Ligase

    • B. 

      Endonuclease

    • C. 

      Helicase

    • D. 

      Topoisomerase

    • E. 

      Polymerase

  • 54. 
    What is the Tm? 
    • A. 

      The temperature at which a double stand of DNA is fully denatured

    • B. 

      The temperature at which a double stand of DNA begins to denature

    • C. 

      The temperature at which half of the helical structure is lost

    • D. 

      The temperature at which the helical structure begins to denature

  • 55. 
    What causes the Tm to be increased? 
    • A. 

      A high AT content

    • B. 

      A high GC content

    • C. 

      A high AC content

    • D. 

      A low AC content

  • 56. 
    Which of the following features do Nucleotides have?
    • A. 

      Pentose sugar groups

    • B. 

      Nitrogenous base

    • C. 

      Phosphate group

    • D. 

      All of the above

  • 57. 
    Pyrimidines are:
    • A. 

      C, T & U

    • B. 

      G, T & U

    • C. 

      A & G

    • D. 

      A, T & U

    • E. 

      G & C

  • 58. 
    What sugar is used in a DNA monomer? 
    • A. 

      3'-deoxyribose

    • B. 

      5'-deoxyribose

    • C. 

      2'-deoxyribose

    • D. 

      Glucose

  • 59. 
    Which base is not found in DNA but found in RNA? 
    • A. 

      Cytosine

    • B. 

      Uracil

    • C. 

      Thymine

    • D. 

      Adenine

  • 60. 
    Each DNA nucleotide is composed of?
    • A. 

      2'-deoxyribose sugar, Nitrogenous base, 5'- hydroxyl

    • B. 

      3'-deoxyribose sugar, Nitrogenous base, 5'- hydroxyl

    • C. 

      3'-deoxyribose sugar, Nitrogenous base, 5'- Phosphate

    • D. 

      Ribose sugar, Nitrogenous base, 5'-hydroxyl

    • E. 

      2'-deoxyribose sugar, Nitrogenous base, 5'- phosphate

  • 61. 
    Which of the following are rules of DNA replication?
    • A. 

      Starts at origin

    • B. 

      Always 3' to 5'

    • C. 

      Semi conservative

    • D. 

      Unidirectional only

    • E. 

      All of the above

    • F. 

      A & C only

  • 62. 
    Drosophila is good for mutant screens as 
    • A. 

      It is small

    • B. 

      It has a short generation time

    • C. 

      It has easily identifiable structures

    • D. 

      All of the above

  • 63. 
    A homeotic mutation: 
    • A. 

      Causes loss of a structure

    • B. 

      Loss of one structure and gain of another

    • C. 

      Is caused by loss of a gene function

    • D. 

      All of the above

  • 64. 
    In situ hybridisation shows
    • A. 

      Where RNA encoded by a gene is found

    • B. 

      Where protein encoded by a gene is found

    • C. 

      Where mutant cells are found

    • D. 

      None of the above

  • 65. 
    What would happen in an Antp loss of function mutation? 
    • A. 

      Loss of antennae and gain of legs

    • B. 

      Loss of legs and gain of antennae

    • C. 

      Loss of wings and gain of legs

    • D. 

      Loss of antennae and gain of wings

  • 66. 
    Define cell fate 
    • A. 

      How the cell will die

    • B. 

      How many multiplications the cell will undergo

    • C. 

      What the cell will become in the future

    • D. 

      None of the above

  • 67. 
    Define an inductive signal
    • A. 

      An intercellular signal which causes replication

    • B. 

      An intercellular signal which causes transcription

    • C. 

      An extracellular signal which causes replication

    • D. 

      An extracellular signal which causes the cell to follow a different fate

  • 68. 
    What change in fate does the organiser graft make? 
    • A. 

      Induces a dorsal fate in cells which would have been ventral

    • B. 

      Induces a ventral fate in cells which would have been posterior

    • C. 

      Induces an anterior fate in cells which would be been posterior

    • D. 

      Induces a left fate in cells which would have been right

  • 69. 
    Which of the following is a feature of tRNA
    • A. 

      Anticodon

    • B. 

      Exon

    • C. 

      Intron

    • D. 

      Poly(A)tail

  • 70. 
    What is the sequence ACCAUGC known as? 
    • A. 

      Klenov fragment

    • B. 

      Okazake fragment

    • C. 

      Kozak sequence

    • D. 

      Stop region

  • 71. 
    Which of the following is not a post translational modification? 
    • A. 

      Poly(A)tail

    • B. 

      Protein folding

    • C. 

      Covalent modification

    • D. 

      Proteolytic cleavage

  • 72. 
    Which form of Nuclear radiation is harmful as a contaminant?
    • A. 

      Alpha

    • B. 

      Beta

    • C. 

      Gamma

    • D. 

      X ray

    • E. 

      Gamma and X Ray only

    • F. 

      Alpha and beta only

  • 73. 
    Which is the best phase to harvest bacterial cells in? 
    • A. 

      Exponential

    • B. 

      Lag

    • C. 

      Stationary

    • D. 

      Death

    • E. 

      None of the Options

  • 74. 
    What feature of PCR makes it less desirable for gene cloning?
    • A. 

      None of the options

    • B. 

      It is more selective

    • C. 

      High temperature damages the gene

    • D. 

      Can clone up to 5 kbp