Molecular Basis of Inheritance Test

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Molecular Basis of Inheritance Test - 58

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Weekly Quiz Competition

Question 1
1 / -0

Consider these sentences regarding the structure and nature of DNA.

I. DNA has two pyrimidine bases that contain single ring structure.
II. In DNA, composition of bases should be $$\displaystyle\frac{A+T}{G+C}=1$$.
III. Each base pair of DNA is $$3.4\overset{o}{A}$$ apart from other base pairs.
IV. The nucleosome model DNA packaging was proposed by Kornberg and Thomas.

Choose the correct statements from the given options.

A
I and III

B
I, II and III

C
II, III and IV

D
I, III and IV

Solution

Erwin Chargaff$$(1950)$$ made a quantitative analysis of DNA and showed that the composition of DNA molecules varies in complex ways depending upon the source of DNA. He proposed Base Equivalence rule or Chargaff's rule, which states that, for double-stranded DNA, the proportion of adenine always equals the thymine and the proportion of guanine always equal to that of cytosine, i.e., $$A=T$$ and $$G=C$$.
It follows that an equal proportion of purines and pyrimidines is always seen in a double-stranded DNA, i.e.,
$$A+G=T+C$$ or $$\displaystyle\frac{A+G}{T+C}=1$$.
The pyrimidine bases like thymine and cytosine have a single nitrogen ring.
The total length of the DNA strand 340 angstrom and the number of base pairs in each turn is 10 base pairs. So, each base pair of DNA is 3.4 angstrom apart.
The nucleosome model DNA packaging was proposed by Kornberg and Thomas.
So, the correct answer is option D.
Question 2
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A protein with $$100$$ amino acid residues has been translated based on triplet genetic code. Had the genetic code been quadruplet, the gene that codes for the protein would have been.

A
Same in size

B
Longer in size by $$25$$%

C
Longer in size by $$100$$%

D
Shorter in size

Solution

Since the genetic code is a triplet, 64 triplets of nucleotides will be involved ( $$4^3$$ = 64). If the genetic code is quadruplet it consists of 256 triplets of nucleotides ($$4^4$$ = 256).
64 triplets coded for 100 amino acid residues. So when 256 triplets are involved in coding the genes that codes for the proteins would have been longer in size by 25%.
Calculation-
(100x 256)/64= 400 amino acids.
Hence the percent change will be (100/400) x100= 25%
Thus the correct answer is option B.
Question 3
1 / -0

During DNA replication, the addition of nucleotides on the lagging strand occurs.

A
Towards the replicating fork

B
At a faster rate than leading occurs

C
Continuously

D
Discontinuously
Solution
- As DNA polymerase replicates DNA only in 5' to 3' direction, replication in the strand with 3'-5' polarity is continuous.
- While replication in 5'-3' strand, is discontinues. The lagging strand is synthesized in short, separated segments. On the lagging strand template, a primase "reads" the template DNA and initiates synthesis of a short complementary RNA primer. A DNA polymerase extends the primed segments, forming Okazaki fragments. The RNA primers are then removed and replaced with DNA, and the fragments of DNA are joined together by DNA ligase.
- So, the correct option is 'Discontinuously'.
Question 4
1 / -0

The pitch angle of deflection between two successive base pairs in DNA double helix is

A
$$20^o$$

B
$$34^o$$

C
$$36^o$$

D
$$360^o$$
Solution
- The DNA in humans is a double helix. Pitch is the number of base pairs in one complete turn of the helix.
- There are 10 base pairs in 1 complete turn and the distance between 2 bases is 0.34nm.
- The deflection between two successive base pairs has a pitch angle of 36$$^o$$.
  Thus the correct answer is option C.
Question 5
1 / -0

Scientists who shared Nobel Prize with Khorana for interpretation of genetic code were

A
Nirenberg and Holley

B
Watson and Crick

C
Cohen and Boyer

D
Wilmut and Campbell

Solution

Har Gobind Khorana shared the 1968 Nobel Prize for Physiology or Medicine with Marshall W. Nirenberg and Robert W. Holley for research that showed the order of nucleotides in nucleic acids, which carry the genetic code of the cell and control the cell’s synthesis of proteins.
So, the correct option is 'Nirenberg and Holley'.
Question 6
1 / -0

Which of the following enzymes is not required for DNA synthesis?

A
Ligase

B
DNase

C
DNA polymerase

D
RNA polymerase

Solution

DNA synthesis is done with the help of Helicase, DNA polymerase, Ligase, and Primase enzymes. Ligase joins DNA strands called Okazaki fragments by catalyzing the formation of phosphodiester bond. Deoxyribonuclease or DNase is an enzyme that breaks the DNA into nucleotides, i.e. degrades the DNA. DNA polmerase is used to make DNA from nucleotides. RNA polmerase helps in replication. Hence, the correct answer is B.
Question 7
1 / -0

Human genome contains base pairs

A
2.5 million

B
25 million

C
27.2 million

D
3.2 billion

Solution

There are four bases adenine (A), thymine (T), guanine (G) and cytosine (C) present in humans. Bases on opposite strands pair specifically as an A always pairs with a T, and a C always with a G. The human genome contains approximately 3.2 billion of these base pairs, which reside in the 23 pairs of chromosomes within the nucleus of all our cells.
So, the correct option is '3.2 billion'.
Question 8
1 / -0

Khorana get Nobel Prize in

A
1958

B
1968

C
1978

D
1982
Solution
- Har Gobind Khorana shared the 1968 Nobel Prize for Physiology or Medicine with Marshall W. Nirenberg and Robert W. Holley for research that showed the order of nucleotides in nucleic acids and how these nucleotides carry the genetic code of the cell and control the cell’s synthesis of proteins.
- So, the correct option is '1968'.
Question 9
1 / -0

Human genome project was launched in

A
1980

B
1987

C
1990

D
1993

Solution

Human Genome Project was launched in 1990 by coordination of US Department of Energy and National Institute of Health. The 13-year mega project was aimed to sequence complete 3 billion DNA base pairs that make up human genome. So, the correct answer is ' 1990'.
Question 10
1 / -0

Human genome project was launched by

A
Khorana and others

B
Bhabha Institute

C
U.S Department of Energy and National Institute of Health

D
NASA

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Re-Attempt Weekly Quiz Competition

Molecular Basis of Inheritance Test - 58

Result

Molecular Basis of Inheritance Test - 58

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SHARING IS CARING

Question 1

I and III

I, II and III

II, III and IV

I, III and IV

Solution

Question 2

Same in size

Longer in size by $$25$$%

Longer in size by $$100$$%

Shorter in size

Solution

Question 3

Towards the replicating fork

At a faster rate than leading occurs

Continuously

Discontinuously

Solution

Question 4

$$20^o$$

$$34^o$$

$$36^o$$

$$360^o$$

Solution

Question 5

Nirenberg and Holley

Watson and Crick

Cohen and Boyer

Wilmut and Campbell

Solution

Question 6

Ligase

DNase

DNA polymerase

RNA polymerase

Solution

Question 7

2.5 million

25 million

27.2 million

3.2 billion

Solution

Question 8

1958

1968

1978

1982

Solution

Question 9

1980

1987

1990

1993

Solution

Question 10

Khorana and others

Bhabha Institute

U.S Department of Energy and National Institute of Health

NASA

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