Tag: structure of chromosome, cell cycle and cell division

Questions Related to structure of chromosome, cell cycle and cell division

Which of the following is TRUE regarding sense and antisense strands?

  1. Both the strands are present on RNA

  2. Both the strands are present on DNA

  3. Sense strand is on DNA and antisense on RNA

  4. Sense strand is on RNA and antisense on DNA


Correct Option: B
Explanation:

Both sense and antisense strands are present in DNA as these act as antisense strand acts as a template during transcription and sense strand has the same sequence as mRNA in the nucleus.

So, the correct option is B.

In which of the following DNA sequences the sequence of nucleotides is the same when one strand is read left to right and the other strand is read right to left?

  1. RFLP

  2. RAPD

  3. VNTR

  4. Palindromic sequence


Correct Option: D
Explanation:
A palindromic sequence is a sequence made up of nucleic acids within double helix of DNA or RNA that is the same when reading from 5' to 3' on one strand and 5' to 3' on the other, complementary strand. 
So, the correct answer is 'Palindromic sequence'.

The double-helix structure of DNA was described by

  1. Watson

  2. J.D. Watson and F. H. C. Crick

  3. Maurice Wilkins

  4. All of the above


Correct Option: D
Explanation:

The structure of DNA was deciphered by Watson and Crick in 1953 on the basis of X-ray diffraction data generated by Wilkins, Astbury and Franklin. Wilkins, Watson and Crick were awarded Nobel prize for their model in 1962.
So, the correct answer is option D.

The characteristic feature of Z-DNA is

  1. Left handed

  2. Right handed

  3. 12 base pairs in each turn

  4. Both A and C


Correct Option: D
Explanation:

DNA duplex of Watson and Crick is right handed and is called as B-DNA. Z-DNA is left handed double helix, which contains zigzag backbone of phosphodiester bonds and 12 base pairs per turn. The diameter of Z-DNA is 18 $\mathring A$ as against B-DNA diameter of 20 $\mathring A$.
So, the correct answer is option D.

Which of the following has higher surface area (SA) to volume (V) ratio?

  1. Red blood cell

  2. Nails

  3. DNA

  4. Human Hair


Correct Option: C

A five carbon sugar with molecular formula $C _5H _{10}O _4$

  1. Deoxyribose

  2. Ribose

  3. Glucose

  4. Lactose


Correct Option: A
Explanation:

Glucose (C$ _6$H$ _1$$ _2$O$ _6$), Deoxyribose (C$ _5$H$ _1$$ _0$O$ _4$), Lactose (C$ _1$$ _2$H$ _2$$ _2$O$ _1$$ _1$), Ribose (C$ _5$H$ _1$$ _0$O$ _5$)

So, the correct answer is option A.

The number of base pairs in each turn of Z-DNA and B-DNA helices respectively is

  1. 9 and 11

  2. 12 and 10

  3. 10 and 13

  4. 12 and 11


Correct Option: B
Explanation:

B-DNA is physiologically the most important form of DNA. The double helical secondary structure model of DNA described by Watson and Crick was the B-DNA. As per the original model, it contains 10 bp per turn but later measurements showed that it contains 10.5 base pairs per turn. Z DNA is the zigzag DNA. It is left handed helix. There are 12 base pair per turn, with a rise of 0.38 nm per base pair.
So, the correct answer is option B.

Which one is correct

  1. Catalytic converter can precipitate particular matter of less than 2-5

  2. Histones are acidic and form core of packing

  3. Template with ${ 5 }'\longrightarrow 3'$ polarity shows continuous DNA replication

  4. Lactobacillus is not present in dough for idli preparation


Correct Option: A
Explanation:
  • DNA replication goes in the 5' to 3' direction because DNA polymerase acts on the 3'-oh of the existing strand for adding free nucleotides.
  • Histones are rich in the basic amino acid residues lysines and arginines and forms histone octamer.
  • Catalytic converters, having expensive metals namely platinum-palladium and rhodium as the catalysts, are fitted into automobiles for reducing the emission of poisonous gases.
  • As the exhaust passes through the catalytic converter, unburnt hydrocarbons are converted into carbon dioxide and water, and carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas, respectively.
  • Fermentation of idli or dosa batter is carried out largely by lactic acid bacteria, the same class of microorganisms that are found in ‘curd.’
  • So the correct answer is " Template with 5′⟶3′ polarity shows continuous DNA replication ".

What is the nature of the 2 strands of a DNA duplex?

  1. Identical & Complimentary

  2. Antiparallel & complimentary

  3. Dissimilar & non complimentary

  4. Antiparallel & non complimentary


Correct Option: B
Explanation:

DNA is a macromolecule of high molecular weight made up of repeating units called nucleotides. Each nucleotide is made up of

 1) a 5 carbon sugar 
2) a phosphate group 
3) a nitrogenous base.
DNA molecule is a helix with bases stacked perpendicularly to the main axis of the molecule. The two strands of a DNA, double helix are called complimentary due to specific base pairing, i.e, each chain has a sequence of nucleotides attached together by phosphodiester bonds joining the adjacent deoxyribose molecules. The base pairing,is specific as adenine is always paired with thymine and guanine with cytosine and vice-versa, i.e, one purine with another pyrimidine and one pyrimidine with another purine. This property of complimentarity makes DNA unique to store and transmit genetic information. The sugar-phosphate backbones of two complimentary strands are antiparallel as they have opposite chemical polarity. Therefore, one strand of the double helix has 5'-3' polarity while the other has 3'-5' polarity. 

The method of DNA replication, in which two strands of DNA separates and synthesize new strands is called as

  1. Dispersive

  2. Conservative

  3. Semi conservative

  4. Non conservative


Correct Option: C
Explanation:

DNA replication, is the process of producing two identical replicas from one original DNA molecule. This biological process, occurs in all living organisms and forms the basis for biological inheritance. DNA is made up of two strands and each strand of the original DNA molecule serves as a template for the production of the complementary strand, a process referred to as semiconservative replication.