Practice Questions

TLS Online TPP Program

#Question id: 23682

Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to

#Unit 13. Methods in Biology

insert the fragments cut with X directly into the plasmid without cutting the plasmid.
cut the plasmid with restriction enzyme X and insert the fragments cut with Y into the plasmid.
cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.
cut the plasmid twice with restriction enzyme Y and ligate the two fragments onto the ends of the DNA fragments cut with restriction enzyme X.

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TLS Online TPP Program

#Question id: 12995

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following constraints affect the stability α-helix,

a) the intrinsic propensity of an amino acid residue to form an α-helix.

b) the interactions between R groups.

c) the bulkiness of adjacent R groups.

d) the occurrence of Pro and Gly residues.

TLS Online TPP Program

#Question id: 12996

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following is incorrect regarding to α-helix

a) In the α helix, the first four NH groups and last four CO groups will normally lack backbone hydrogen bonds.

b) the length of an amino acid in α-helix reduced almost 3 times than linear structure.

c) the frequent occurrence of Pro and Gly residues favour α-helix formation.

d) dihedral (ϕ and ψ) angle should be close to -57 and -47.

TLS Online TPP Program

#Question id: 12997

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the given reason is correct to minimize the repulsion in an α-helix

a) positively charged amino acids are often found near the amino terminus of the helical segment

b) negatively charged amino acids are often found near the amino terminus of the helical segment

c) positively charged amino acids are often found near the C-terminus of the helical segment.

d) negatively charged amino acids are often found near the C-terminus of the helical segment.

TLS Online TPP Program

#Question id: 12998

#Unit 1. Molecules and their Interaction Relevant to Biology

Match with appropriate bonding pattern

TLS Online TPP Program

#Question id: 12999

#Unit 1. Molecules and their Interaction Relevant to Biology

Proline and glycine both disturb the symmetry of α-helix which of the following are true regarding to these two amino acids

a) proline changes the orientation of hetropolymeric α-helix hence proline can be placed only as 1st amino acid residue near to C-terminus

b) proline changes the orientation of polymeric α-helix hence proline can be placed only as 1st amino acid residue near to N-terminus

c) glycine disrupts the heteropolymeric α-helix by changing the helicity.

d) homopolymer of proline and glycine can form stable helix.

TLS Online TPP Program

#Question id: 13000

#Unit 1. Molecules and their Interaction Relevant to Biology

Identify the correct statement regarding the structure