Escherichia coli cells were grown for many generations in 15NH4Cl as sole nitrogen source. Subsequently, these cells were grown exactly for four generations in medium containing 14NH4Cl. The DNA from these cells were isolated and separated. If 15N/15N represents the two strands of DNA where both strands have heavy nitrogen; 15N/14N as intermediate DNA; and 14N/14N as DNA containing light nitrogen, the ratios for heavy: intermediate: light DNA, respectively would be:
(1) 1 : 0 : 7
(2) 1 : 1 : 6
(3) 0 : 1 : 7
(4) 0 : 8 : 0
Match each item in COLUMN I with one in COLUMN II and select your answer from the codes given:
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COLUMN I |
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COLUMN II |
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SCIENTIST |
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CONTRIBUTION |
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A. |
Francis Crick |
a. |
Breaking the genetic code |
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B. |
Nirenberg |
b. |
Established Caenorhabditis elegans as a model genetics study organism |
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C. |
Benzer |
c. |
Central dogma of molecular biology |
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D. |
Brenner |
d. |
Bacteriophage genetics |
Codes:
A. B. C. D.
1. c a d b
2. c a b d
3. a b c d
4. a c d b
The base pairing in a double stranded DNA is correctly described as:
(1) Similar
(2) Identical
(3) Complementary
(4) Synergistic
If each strand of a ds DNA acts as a template for new strand, the two daughter DNA will be:
(1) Complementary to each other
(2) Identical to the parental DNA
(3) Similar to each other
(4) Complementary to the parental DNA
In some viruses, the flow of genetic information is from RNA to DNA. These viruses are:
(1) Reverse transcriptase
(2) Teminism
(3) Ribozymes
(4) Retroviruses
In prokaryotes:
(1) A typical nucleus is not seen and DNA is scattered throughout the cell
(2) A typical nucleus may sometimes be present and DNA is scattered throughout a cell
(3) A typical nucleus is not seen but DNA is not scattered throughout the cell
(4) A typical nucleus may sometimes be present but DNA is not scattered throughout the cell
Histones are rich in amino acids:
(1) Arginine and Lysine
(2) Argine and Leucine
(3) Arginine and Isoleucine
(4) Aspartate and Glutamate
A typical nucleosome unit consists of about:
1. 60 base pairs
2. 140 base pairs
3. 200 base pairs
4. 400 base pairs
During DNA packaging in eukaryotic cells, Non Histone Chromosomal proteins:
1. Are not required
2. Are required from the beginning to the end of packaging
3. Are required only for earlier stages of packaging
4. Are required for higher level of packaging
Frederick Griffith discovered:
(1) DNA is the genetic material
(2) RNA can be the genetic material
(3) Sterptococcus has two strains
(4) Bacterial transformation
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