Q. No.Regulation of lac operon by repressor is referred to as:
1. Inducible regulation
2. Repressible regulation
3. Negative regulation
4. Positive regulation
Fredrick Griffith accidentally discovered transformation when attempting to develop a vaccine for pneumonia. He injected mice with samples from S-strain (virulent) and/or R-strain (nonvirulent) pneumococci bacteria (Sterptococcus pneumoniae). Which of the following results is NOT consistent with Griffith's experiments?
| 1. | injected S-strain; mouse dies. |
| 2. | injected R-strain; mouse lives. |
| 3. | injected heat-killed S-strain; mouse lives. |
| 4. | injected mixture of heat-killed S-strain and live R-strain; mouse lives. |
Which scientists first gave experimental evidence that DNA is the genetic material?
| 1. | Avery, MacLeod , and McCarty who repeated the transformation experiments of Griffith, and chemically characterized the transforming principle. |
| 2. | Garrod, who postulated that Alcaptonuria, or black urine disease, was due to a defective enzyme. |
| 3. | Beadle and Tatum, who used a mutational and biochemical analysis of the bread mold Neurospora to extablish a direct link between genes and enzymes. |
| 4. | Meselson and Stahl who showed that DNA is replicated semiconservatively. |
The function of the rho protein is
1. to help terminate translation
2. to help RNA polymerase bind to the DNA
3. to help RNA polymerase find a promoter
4. to help terminate transcription
Genetic information in a DNA molecule is coded in the:
1. Sequence of nucleotides
2. Base pairings
3. Proportion of each base present
4. The turning pattern of the helix
In general, bacterial genes are regulated at the time of:
1. Transcription
2. Post transcription
3. Translation
4. Post translation
Match each item in Column I with one item in Column II and chose your answer from the codes given below:
|
Column I (nRNA codons) |
Column II (Amino Acid) |
|
I. GUG II. UGG III. UAC IV. GAG |
1. Tryptophan 2. Valine 3. Glutamic acid 4. Tyrosine |
Codes
I II III IV
1. 1 2 3 4
2. 2 1 4 3
3. 2 1 3 4
4. 1 2 4 3
Match each item in Column I with one item in Column II and chose your answer from the codes given below:
Column I Column II
(antibiotic) (effect)
I. Tetracycline 1. inhibits binding of aminoacyl tRNA to the ribosome
II. Streptomycin 2. inhibits initiation of translation
III. Chloramphenicol 3. inhibits peptidyl transferase
IV. Erythromycin 4. inhibits translocation of mRNA along with ribosome
Codes:
1. 1 2 3 4
2. 2 1 4 3
3. 2 1 3 4
4. 1 2 4 3
The association of histone H1 with a nucleosome indicates
1. transcription is occuring
2. DNA replication is occuring
3. the DNA is condensed into chromatin fibre
4. the DNA double helix is exposed
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