MOLECULAR BIOLOGY Question Papers (Supple, 2006)

SET: 1

1. What is the relationship between nucleosomes, 30nm fibers and the scaffold structure with respect to the organisation of DNA in the nucleus?

2. Why is the 3’OH group on the ribose ring so important for DNA & RNA synthesis?

3. Eukaryotic mRNA is usually monocistronic. What does this mean? Why is thes the case for eukaryotes, where as polycistronic mRNA is often found in prokaryotes?

4. Describe the following terms ribosome binding site, RNA polymerase, tRNA synthetases.

5. Write short notes on

(a) Thymine dimers

(b) Error prone repair

6. Describe the Ames assay for screening potential environmental mutagens. Why is it though that a compound that tests positively in the Ames assay may also be carcinogenic?

7. Describe the basis for chromosome mapping in Hfr × f – crosses.

8. What are the differences among an IS element, a transposon, an intron and a plasmid.

SET: 2

1. What are the roles of RNAprimers and Okazaki fragments during DNA replication.

2. Describe Messelson-Stahl experiment.

3. Write the following

(a) RNA pol “basal” factors

(b) RNA pol “Transcription factors”

4. Write briefly on the different types of protein that exists.

5. What is significantly different about the type of DNA “damage” repaired by mismatch repair compared to other types of DNA damage?

6. Write a note on microbial testing that are widely used in industrial reasearch.

7. What is the role of Rec protien in bacterial recombination?

8. Describe lysis and lysogeny.

SET: 3

1. What are the features of the DNA molecule described by Watson & Crick? Are these features the same for all DNA molecules?

2. DNA relplication is bidirectional. What would the replication bubble look like (using the same labelling regimen as discussed in class) if replication was unidirectional?

3. Write short notes on

(a) rho dependent termination

(b) rho independent termination

4. What will determine whether regions of alpha-helical structure lie at the surface or in the interior of a water-soluble globular protien?

5. What is meant by reverse genetics? How is it useful?

6. Describe the the Ames assay for screening potential environmental mutagens. Why is it though that a compound that tests positively in the Ames assay may also be carcinogenic?

7. With respect to F+ and F- bacterial mating, answer the following:

(a) How was it established that physical contact was necessary?

(b) How was it established that chromosome transfer was unidirectional?

8. What are the differences among an IS element, a transposon, an intron and a plasmid.

SET: 4

1. Summarise and compare the properties of DNA polymerase – І, ІІ, ІІІ.

2. In Meselson-stahl experiment, which of the three modes of replication could be ruled out after one round of replication? After two rounds?

3. What processing events occur with prokaryotic Mrna?

4. Which feature of the Genetic code is responsible for redundancy of Genetic Code.

5. What is significantly different about the type of DNA “damage” repaired by mismatch repair compared to other types of DNA damage?

6. Write a short note on split genes.

7. What is the role of Rec protien in bacterial recombination?

8. Describe what are the three different physical forms of phage λ chromosome?