In an operon:
I:
a polycistronic structural gene is regulated by a common promoter and regulatory genes
II:
the regulation is always negative and inducible
1.
Only I is correct
2.
Only II is correct
3.
Both I and II are correct
4.
Both I and II are incorrect
Subtopic: Â Gene Regulation: Lac Operon |
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Level 2: 60%+
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The bacterium Escherichia coli was not used by:
| 1. | Fred Griffith, when he discovered bacterial transformation |
| 2. | Alfred Hershey and Martha Chase, when they conclusively proved that DNA is the molecule that stores genetic information |
| 3. | Matthew Meselson and F. Stahl, when they experimentally proved that DNA replicates semi-conservatively |
| 4. | Francois Jacob and Jacques Monod, when they proposed the working of lactose operon |
Subtopic: Â Search for Genetic Material |
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All the following statements regarding histones, the proteins used in packaging of DNA, are correct except:
| 1. | They are rich in amino acids - Lysine and Arginine. |
| 2. | They carry a positive charge on the side chain. |
| 3. | They are organized to form a unit of 8 molecules. |
| 4. | The pH of histones is slightly acidic. |
Subtopic: Â DNA Packaging |
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Level 1: 80%+
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A double stranded DNA molecule from a bacteriophage is found to consist of 23% adenine bases. The expected percentage of guanine in this DNA molecule will be:
| 1. | 23 % | 2. | 27 % |
| 3. | 46 % | 4. | 54 % |
Subtopic: Â The DNA |Â DNA Double Helix |
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In the human genome:
| 1. | the total number of genes are about 60000 |
| 2. | less than 2 percent of genome does not code for proteins |
| 3. | repeated sequences are rarely found |
| 4. | SNPa occur at about 1.4 million locations |
Subtopic: Â Human Genome Project |
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Level 1: 80%+
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Identify the incorrect match:
| mRNA codon | Amino acid | |
| 1. | AUG | Methionine |
| 2. | GGG | Glycine |
| 3. | UGA | Tryptophan |
| 4. | UAG | None; it is a stop codon |
Subtopic: Â Genetic Code |
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Identify the incorrect statement:
| 1. | Transcription and translation can be coupled in prokaryotes |
| 2. | DNA is a better genetic material than RNA |
| 3. | It is the presence of structural gene in a transcription unit that defines the template and coding strands |
| 4. | RNA polymerase III is responsible for transcription of tRNA, 5srRNA and snRNAs |
Subtopic: Â Transcription |
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The genetic code is:
| 1. | triplet, degenerate, nearly universal and read in a contiguous fashion |
| 2. | triplet, degenerate, nearly universal and read in an overlapping fashion |
| 3. | doublet, degenerate, nearly universal and read in a contiguous fashion |
| 4. | triplet, ambiguous, totally universal and read in a contiguous fashion |
Subtopic: Â Genetic Code |
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Consider the given statements:
| I: | Griffith discovered the process of bacterial transformation. |
| II: | Hershey and Chase unequivocally proved that DNA is the genetic material. |
| III: | Meselson and Stahl showed that DNA replicated semi-conservatively. |
| 1. | Only I and II are correct |
| 2. | Only I and III are correct |
| 3. | Only II and III are correct |
| 4. | I, II and III are correct |
Subtopic: Â DNA Replication |Â Search for Genetic Material |
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The lac operon can be described as:
| 1. | an inducible operon with a positive regulation by the repressor protein |
| 2. | an inducible operon with a negative regulation by the repressor protein |
| 3. | a repressible operon with a positive regulation by the repressor protein |
| 4. | a repressible operon with a negative regulation by the repressor protein |
Subtopic: Â Gene Regulation: Lac Operon |
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