Q. No.Which of the following is likely if there is a mutation in the lacY gene of the lac operon in E.coli?
1.
The lac genes would be expressed efficiently only in the absence of lactose.
2.
The lac genes would be expressed efficiently until the lactose supply in the cell is exhausted.
3.
The lac genes would be expressed continuously.
4.
Expression of the lac genes would cease immediately.
The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that:
| 1. | The nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose. |
| 2. | The nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups. |
| 3. | ATP contains three high-energy bonds; the nucleoside triphosphates have two. |
| 4. | ATP is found only in human cells; the nucleoside triphosphates are found in all animal and plant cells. |
Which of the following pairs of codons encode the same amino acid?
| 1. | AUG and AUC | 2. | UAA and UAC |
| 3. | GUA and GUG | 4. | UAG and UAC |
Griffith wanted to make a vaccine to prevent pneumonia. He injected heat-killed S-strain bacteria into the mice for this purpose. How can a killed bacteria help in making a vaccine?
| 1. | The heat-killed bacteria is a more potent toxin than the live one. |
| 2. | Protein denaturation due to heat changes the proteins of the bacterium. |
| 3. | Molecules from the cell surface are still intact and can provoke an immune response. |
| 4. | DNA molecules can transform other strains of bacteria. |
Griffith's experiment discovered bacterial transformation which in his experiment means:
| 1. | A mutation in the R strain made them virulent. |
| 2. | A mutation in the S strain made them non-virulent. |
| 3. | A rough strain passed genetic information to a smooth strain. |
| 4. | A smooth strain passed genetic information to a rough strain. |
Avery, MacLeod, and McCarty used DNase in their experiment because:
| 1. | It enabled them to isolate pure DNA samples. |
| 2. | It enabled them to isolate pure protein samples. |
| 3. | This allowed them to demonstrate that removing the DNA prevents transformation. |
| 4. | It made sure that RNA will always be present when they attempted to transform the R strain. |
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What key observation regarding Garrod'sinborn of metabolism leads to a landmark discovery in molecular biology?
| 1. | Identification of a defective gene in individuals with alkaptonuria. |
| 2. | Identification of a defective gene in parents of alkaptonuria patients. |
| 3. | Identification of a defective enzyme in individuals with alkaptonuria. |
| 4. | Identification of the inheritance pattern of alkaptonuria as autosomal recessive. |
T2 bacteriophage was used by Hershey and Chase to conclusively prove that DNA and not protein is the genetic material because:
| 1. | It makes capsomeres with the help of its genes. |
| 2. | It injects its genetic material into a bacterial cell. |
| 3. | It can undergo either the lytic or lysogenic life cycle |
| 4. | It enters the bacterial cell to cause infection. |
Identify the correct statements regarding a replisome:
| I: | It is a complex of several proteins. |
| II: | It includes enzymes like DNA polymerase, DNA helicase, and primase. |
| III: | It is found at the replication fork during DNA synthesis. |
| 1. | I and II only | 2. | I and III only |
| 3. | II and III only | 4. | I, II, and III |
The origin of replication is a particular sequence in a genome at which replication is initiated. This region is AT-rich because:
| 1. | DnaA proteins bind to AT-rich sites. |
| 2. | DnaC proteins bind to AT-rich sites. |
| 3. | AT base pairs are more easily separated than GC base pairs. |
| 4. | AT base pairs contain more hydrogen bonds than GC base pairs. |
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