Question 33 Proteins with just one polypeptide chain have pr

Question 33

Proteins with just one polypeptide chain have primary, secondary and __________ structures.

helical

beta sheet

quaternary

tertiary

none of the above

1 points

Question 34

The __________ program compares a new polypeptide sequence with all sequences stored in a data bank.

BLAST

CRUSH

MIGRATION

GenBank

None of the above

1 points

Question 35

-Amino acids have an amino group and a ___________ group attached to a central carbon atom.

methyl

carboxyl

omega

beta

hydroxyl

1 points

Question 36

The transition from the double helical structure (native state) to randomly coiled single strands is called _______________.

renaturation

denaturation

randomization

relaxation

none of the above

Solution

Ans. 33. Correct option. D. tertiary.

Primary, secondary, tertiary and quaternary structures are four levels of protein organization. A protein with single polypeptide chain can attain primary, secondary and tertiary structures. To attain quaternary structure, a protein must contain two or more polypeptides because quaternary structure is the association between two of more polypeptides forming a single protein molecule.

Option A (helical, or helix) and B (beta sheet) are just examples of secondary structures itself. So, these don’t fit well in the progressive level of organization of protein.

Option C is also incorrect. See above.

Ans. 34. Correct option. A BLAST

Protein Basic local alignment search tool (BLAST) compares the sequence of a polypeptide with those stored in the database.

GenBank is the biorepository of the genetic material of organism. It does not compare polypeptide sequence.

B and C options do not belong to bioinformatics. And has nothing to do with biology.

Ans. 35. Correct option. Carboxyl group.

An amino acid has an amino and carboxyl acid group linked to its alpha carbon, thus named amino acid.   

Methyl group (in alanine) is also lined to alpha carbon of alanine, but it’s the side that is different for different amino acids. So, this option is not always true, for example, glycine has H-atoms linked to alpha carbon.

Option C, D, E are not linked to alpha carbon of an amino acid.

Ans. 36. Denaturation.

The process of disrupting protein native structure, i.e. transition from native state (say, tertiary structure, functional form of protein) to randomly coiled single strand (secondary structure, non-functional form), leading to loss of function is called denaturation. A functional protein has all the secondary structures (alpha helices, beta sheets), motifs, etc. arranged in a well-defined manner.

Renaturation is the process of re-gaining function by a denatured protein. For example, a sample of protein stored at -20⁰C is denatured because it loses its catalytic activity. When thawed to room temperature, the protein regains its function- the process is said to be renaturation.

Randomization does not depict structure of protein. Relaxation does not indicate change of protein into denatured state.