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DNA Structure and Replication

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Questions

Question 1 Multiple Choice (Single Answer)

The DNA strands are antiparallel because of
A. orientation of nitrogenous bases
B. phosphodiester bonds
C. orientation of sugar and phosphate molecules
D. structure of the deoxyribose sugar
E. hydrogen bonds

  1. B and D
  2. B, C and D
  3. Only A
  4. A, B and E
Question 2 Multiple Choice (Single Answer)

With reference to the properties of sugars in DNA, answer the following question.

What would be the expected change in the DNA structure if the 1' position of the deoxyribose sugar is silenced?

  1. The double helical structure will distort and bend towards right.
  2. The complete double helical structure will be destroyed.
  3. The stack space will be highly decreased thus minimising the helical rise.
  4. There would not be a visible change in the structure although physico-chemical properties would be affected.
Question 3 Multiple Choice (Single Answer)

For dsDNA, which of the following will always be equal to 1?
i. (A+T)/(G+C)
ii. C/T
iii. A/G
iv. (A+G)/(C+T)

  1. Only i and iv
  2. Only iii
  3. Only ii and iii
  4. Only i
Question 4 Multiple Choice (Single Answer)

DNA having labelled thymidine is allowed to replicate in medium having non-radioactive thymidine. After 3 replications, the number of DNA molecules having labelled thymidine shall be

  1. one
  2. two
  3. four
  4. eight
Question 5 Multiple Choice (Single Answer)

A student isolates the dsDNA from a novel virus that it is subjected to genomic analysis. It reveals that the molecule contains 14% thymine. What would you predict for the %C (cytosine)?

  1. 72%
  2. 28%
  3. 36%
  4. 14%
Question 6 Multiple Choice (Single Answer)

Which amongst the given can be proficiently defined as a gene that results from integration into genome of a reverse-transcribed copy of an mRNA?

  1. Transfected gene
  2. Orthologous gene
  3. Fused gene
  4. Processed pseudogene
Question 7 Multiple Choice (Single Answer)

In which of the following cases would you assert that the virus used the host DNA to replicate?

  1. If radioactive sulfur from a bacteriophage is found in a bacterium
  2. If radioactive phosphorus from a bacteriophage is found in a bacterium
  3. If radioactive phosphorus from a bacterium is found in a bacteriophage
  4. If radioactive sulfur from a bacterium is found in a bacteriophage
Question 8 Multiple Choice (Single Answer)

With reference to the properties of sugars in DNA, fill in the blanks.

The ribose sugar and deoxyribose sugar are ____ carbon sugars and they both differ in an oxygen (O) at ___ position.

  1. 5; 1'
  2. 6; 3'
  3. 6; 2'
  4. 5; 2'
Question 9 Multiple Choice (Single Answer)

The individual zone of a chromosome that replicates as a discrete section is called

  1. telomere
  2. euchromatin
  3. replication unit
  4. linker DNA
Question 10 Multiple Choice (Single Answer)

Assertion: Artificially synthesised genes in which non-coding regions have been excluded fails to express proteins in-vivo.
Reason: Their m-RNA molecules fail to move through the pores in the nuclear envelope.

  1. Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
  2. Both Assertion and Reason are correct and Reason is not the correct explanation of Assertion.
  3. Assertion is correct but Reason is wrong.
  4. Both Assertion and Reason are incorrect.
Question 11 Multiple Choice (Single Answer)

The nucleus from a cell of a developed organism was transplanted to an egg cell that grew into a normal adult. On which organism was the very first nuclear transplant performed?

  1. Mouse
  2. Sheep
  3. Cat
  4. Frog
Question 12 Multiple Choice (Single Answer)

The helical double stranded structure of DNA would have been named after Rosalind Franklin but her results were hindered by the lack of

  1. precision instruments
  2. strong x-rays
  3. true crystals
  4. recurrent contamination of samples
Question 13 Multiple Choice (Single Answer)

Assertion: Majority of the genome is non-coding but it also has very important role to play almost equal to the coding DNA.
Reason: DNA fingerprinting matches the variable number of tandem repeats in order to conclude the results.

  1. Assertion and Reason both are correct and Reason is the correct explanation of Assertion.
  2. Assertion and reason both are correct and Reason is NOT the correct explanation of Assertion.
  3. Assertion is correct but Reason is wrong.
  4. Assertion and Reason both are incorrect.
Question 14 Multiple Choice (Single Answer)

During DNA replication, the sequence 5'-TpApGpAp-3' would produce

  1. 5'-TpCpTpAp-3'
  2. 5'-UpCpUpAp-3'
  3. 5'-GpCpGpAp-3'
  4. 5'-ApTpCpTp-3'
Question 15 Multiple Choice (Single Answer)

Match the functions of the enzymes involved in DNA replication and choose the correct option from the alternatives given below.

 
ENZYME FUNCTION
A. DNA Polymerase III I. Stabilisation of the single stranded DNA strand
B. Helicase II. Nicks and cuts the backbone and relieves the tension of unzipped strand
C. Topoisomerase III. Synthesises new strand from RNA primer
D. DNA Polymerase I IV. Joins the backbone of newly synthesised strand
E. RNA Polymerase V. Unzipping DNA double strand
F. SSBP VI. Replaces RNA with DNA
G. DNA Ligase VII. Lays down the RNA primer
  1. A - VI, B - V, C - I, D - III, E - VII, F - II, G - IV
  2. A - III, B - V, C - II, D - VI, E - VII, F - I, G - IV
  3. A - VII, B - V, C - II, D - VI, E - III, F - I, G - IV
  4. None of these
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