OBJECTIVES OF MOLECULAR GENETIC CELLULAR CONTROL

Multiple Choice Questions MCQs

  • Four options are given at the end of each statement. You should

encircle one option from them.

  1. Franklin’s X-ray data indicate that the helix makes one full turn after
    every.

(a) 2.4 nm                   (b) 3.4 nm                 (c) 34 nm                  (d) 4.3 nm

  1. The helix has a uniform width:

(a) 2 nm                       (b) 3 nm                    (c) 4 nm                    (d) 5 nm

  1. Peptide bond is formed on:

(a) A site                      (b) P site                   (c) E site                   (d) None

  1. The formation of puff in insects is controlled by:

(a) Insulin                   (b) Ecdysone           (c) transferase         (d) None

  1. Anticodon is present in:

(a) mRNA                    (b) tRNA                   (c) rRNA                   (d) None

  1. Which of the followings is initiation codes:

(a) UAA                       (b) UCC                    .(c) AUG                    (d) GUC

  1. Which of the followings is termination codes:

(a) UAA                       (b) UCC                    (c) AUG                     (d) GUC

  1. The enzyme which join the pieces of the DNA is:

(a) Primase                 (b) Ligase                 (c) Helicase              (d) None

Ans:

1. (b) 2. (a) 3. (b) 4. (b) 5. (b) 6. (c) 7. (a) 8. (b)

Fill in the blanks

1. Deoxyribonucleic acid or DNA is the material.

These strands open up to form a replication ____________

An enzymes •                            catalyzes elongation of new DNA.

The enzyme DNA polymerase can only add nucleotides to the free___________
end of a DNA strand.

The lagging strand is first synthesized as a series of segments. These

pieces are called _______________

The center loop is called.___________ loop.

An enzyme_________________ transferase breaks the bond between the amino
acid and tRNA in the P site.

The transcription factors bind selectively to the ____________ regions of DNA.

The formation of puff is controlled by a hormone______________

10. In this case the mutant condition is taken as a ______________ , or hereditary

11. Alterations in change of codon of an amino acid to a stop signal are called

____________ mutation.

12. Base____________ are chemicals that are similar to normal DNA bases But they pair incorrectly.

Ans:

1. genetic       2. bubble      3 . DNA polymerases       4. 3′     5. Okazaki fragments 6. anticodon      7. peptidyl      8. enhancer     9. ecdysone

10. genetic disorder   11. nonsense     12.analogues

Short Questions

1          What is the function of rRNA?

Ans: Transfer RNA (tRNA) picks up amino acids in the cytoplasm and carries

them to ribosomes. It joins these amino acids for the synthesis of

Give different function of enzymes involved in the transcription.

Ans: They unwind a region of a DNA molecule. They initiate and end mRNA

synthesis. They also modify the mRNA after the completion transcription.

What are primary transcripts?

Ans: The newly transcribed mRNA is called the primary transcript.

What is the function of RNA splicing?

Ans:, Some base sequences in newly transcribed mRNA do not code for

proteins. RNA splicing cut out these noncoding regions.

What is anticodon?

Ans: The center loop of tRNA is called anticodon loop. It has a sequence of

three unpaired bases called the anticodon.

What is the function of peptidyl transferase?

Ans: An enzyme peptidyl transfercase breaks the bond between the amino acid

and tRNA in the P site. It also catalyzes the formation of a peptide bond between that amino acid and the amino acid in the A site.

  1. What is harmless missense mutation?

Ans: There is redundancy of the genetic code. So some substitution mutations have no effect on the protein coded. In other words, a change in a base pair may transform one codon into another. The new codon is translated into the same amino acid.

  1. What is nonsense mutation?

Ans: Alterations in change of codon of an amino aid to a stop signal are called nonsense mutation.

  1. What are mutagens and mutagenesis?

Ans: The creation of mutations is called mutagenesis Mutagen is a chemical or physical agent that causes mutation.

  1. What is recombinant DNA and DNA technology?

Ans: The DNA which contains DNA from two different sources is called Recombinant DNA and the technology for the formation of recombinant DNA is called DNA technology.


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  1. What is vector?

Ans: The means by which recombinant DNA is introduced into a host cell is called vector.

True/ False                  (For Punjab University only)

Marks are True or False statement. Give correct statement if false •

Statement

  1. The cytosine and thymine are purine bases.
  2. These strands open up to form a replication “bubble.”
  3. An enzymes RNA polymerases catalyzes elongation of new DNA at a replication fork.
  4. Okazaki fragments are about 100 to 200 nucleotides long in eukaryotes.
  5. The primer is a short stretch of RNA. It is synthesized by another enzyme
    ligase.
  6. Ligase joins all the DNA fragments into a strand.
  7. A sequence of bases in DNA that codes for the synthesis of one polypeptide is called gene.
  8. DNA must code for the 30 different amino acids.
  9. Hence more than one codon can specify same amino acid because This characteristic of the code is called degeneracy.
  10. The codon AUG codes for the amino acid lysine.
  11. The synthesis of messenger RNA from DNA is called transcription.
  12. The newly transcribed mRNA is called the primary transcript.
  13. Ligase cut out these noncoding regions.
  14. The transcription factors bind selectively to the enhancer regions of DNA.
  15. The formation of puff is controlled by a hormone ecdysone.
  16. Alterations in change of codon of an amino acid to a stop signal are called nonsense mutation.Ans:
    Statement T/F Correct Statement
    . The cytosine and thymine are purine bases. F       , The cytosine and thymine are pyrimidine bases.
    : . These strands open up to form a replication “bubble.” T  
    :. An enzymes RNA polymerases catalyzes elongation of new DNA at a replication fork. F An enzymes DNA polymerases catalyzes elongation of new DNA at a

    replication fork.

    1.  
    Okazaki fragments are about 100 to
    200 nucleotides long in eukaryotes.
    T  
    The primer is a short stretch of RNA. It is synthesized by another enzyme ligase. F The primer is a short stretch of RNA. It is synthesized by another enzyme primase.
    Ligase joins all the DNA fragments into a strand. T  
    7 A sequence of bases in DNA that codes for the synthesis of one polypeptide is called gene. T  
    8 DNA must code for the 30 different amino acids. F DNA must code for the 20 different amino acids.
    9 Hence more than one codon can specify same amino acid because. This characteristic of the code is called

    1. .
    T  
      The codon AUG codes for the amino acid lysine. F The codon AUG codes for the amino acid methionine.
    1′ . The synthesis of messenger RNA from DNA is called transcription. T  
    The newly transcribed mRNA is called

    the primary transcript.

    ._

    T  
      1:..Ligase

    cut out these noncoding         •
    regions.

    F RNA splicing cut out these noncoding regions.
    The transcription factors bind selectively to the enhancer regions of T  

     

     

    ..  
    15.The formation of puff is controlled by a hormone ecdysone. T  
    16.Alterations in change of codon of an • amino acid to a stop signal are called nonsense mutation. T  

     

 

 

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