The diagram of a nucleosome is shown above.
(i) Identify the parts labeUed a, b, c and d in it.
(ii) Name the positively-charged and negatively charged components in it.

The Central dogma of molecular biology is shown above.
(a) Who proposed this?
(b) Identify the processes A, Band C in the above representation.
(c) Why is it not applicable to certain viruses?

A stage in the process of transcription in a prokaryote is shown above.
(a) Name the stage in transcription.
(b) Identify A and B in the diagram.
(c) Can this process be coupled to translation ? Justify your answer.

Read the following and answer any four questions from (i) to (v) given below:
In prokaryotes, DNA is circular and present in the cytoplasm but in eukaryotes, DNA is linear and mainly confined to the nucleus. DNA or deoxyribonucleic acid is a long polymer of nucleotides. In 1953, the first correct double helical structure of DNA was worked out by Watson and Crick. Based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin. It is composed of three components, i.e., A phosphate group, a deoxyribose sugar and a nitrogenous base. Different forms of DNA are B-DNA, Z-DNA, A-DNA, C-DNA and D-DNA.
(i) Name the linkage present between the nitrogen base and pentose sugar in DNA.

(ii) The double helix structure of DNA was proposed by

(iii) The double chain of B-DNA is coiled in a helical fashion. The spiral twisting of B-DNA duplex produces

(iv) Assertion: The two strands of DNA helix have uniform distance between them.
Reason: A large sized purine always paired opposite to a small sized pyrimidine.

 (v) Which of the following describes the structure of B-DNA?

Read the following and answer any four questions from (i) to (v) given below :
Translation is the process of polymerisation of amino acids to form a polypeptide. The order and sequence of amino acids are defined by the sequence bases in the mRNA. The amino acids are joined by a bond called peptide bond. Ribosome is the site of protein synthesis.
(i) Which ion is essential for association of both units of ribosome at the time of protein formation ?

(ii) During translation, how many initiation factors are required in eukaryotes for initiation reactions?

(iii) Which part of mRNA contains untranslated regions (UTR)?

(iv) Name the enzyme that helps in combining amino acid to its particular tRNA.

(v) From the given list, select the translation machinery.
1. mRNA
2. Ribosomes
3. Amino acids
4. tRNAs
5. Peptidyl transferase
6. Amino acyl tRNA synthetase
7. Pyrophosphatase