Question

1. The alpha-tubulin molecule is composed of 450 amino acids. What is the minimum number of base pairs of DNA needed to encode the alpha-tubulin molecule?

A. 1350

B. 1335

C. 450

D. 445

2. Compared to a 0.5 M NaCl solution, a 0.2 M NaCl solution is __________.

A. hypotonic

B. hypertonic

C. isotonic

D. neotonic

3. You have identified a frame-shift mutation very near the N-terminus of the protein you are studying. What will be the MOST LIKELY effect on the function of the protein?

A. no effect, as the amino acids are the same, just shifted

B. the protein will be non-functional, as nearly all the amino acids will be different compared to the non-mutated protein

C. the protein will probably not be affected very much as the frame-shift mutation occurs near the end of the protein

4. Which of the following molecules are present in RNA, but not DNA?

A. adenine

B. guanine

C. phosphate group

D. ribose

E. thymine

5. Which of the following processes is central to the initiation of transcription in bacteria?

A. binding of sigma factor to the promoter region of a gene

B. formation of a phosphodiester bond in the elongating RNA strand

C. binding of DNA polymerase to the promoter region

D. formation of a DNA primer

E. binding of RNA polymerase to the enhancer region of a gene

6. Which of the following is false with regards to the DNA repair process in eukaryotes?

A. DNA repair proteins are constantly surveying our cells' DNA for damage and repairing the damage.

B. Damaged DNA can only be repaired during the S phase of the cell cycle.

C. Different kinds of DNA damage requires different DNA repair proteins.

D. A and C are both false.

Answer 1

1. Ans is option A.

Each amino acids are coded by a codon. A codon is a triplet combination of nucleotides which signifies a amino acid. Thus codon on mRNA is complementary to the template strand of DNA. Thus 1 amino acid is designated by 3 base pairs. 450 amino acids will be encoded by (450x3) = 1350 base pairs.

2. Ans is option A. When the concentration of a solution is less with respect to another solution, then the first solution is known as hypotonic solution.
When the concentration of a solution is more with respect to another solution, then the first solution is known as hypertonic solution.

When the concentration of a solution is same with respect to another solution, then the the solutions are known as isotonic solution to each other.

3. Ans is option B.

The peptide chain synthesis always starts from the N terminal. When, there is a frame shift mutation, it causes alteration of the frame of reading of the bases, and can alter the codon sequence. This will cause abnormal signalling and reading of codons, causing alteration of amino acid sequence. Thus will alter the function of protein and it cbecome non functional. As the mutation is occurring at N - terminal, almost the whole chain will alter, making the polypeptide non functional.

4. Ans is D.

RNA and DNA is formed by polynucleotide. Each nucleotide contains, a nitrogenous base, a pentose sugar and a phosphate group. In case of RNA, the pentose sugar is ribose and in case if DNA, the pentose sugar is deoxy-ribose.

In RNA, adenine, guanine, cytosine and uracil are present. In DNA uracil is replaced by thymine.