Following statements are regarding to recognition of sperm by mammalian zona pellucida.

A. Sperm that have undergone the acrosome reaction bind directly to zona protein ZP2 and begin making a channel toward the oocyte.

B. Sperm with an intact acrosome bind to ZP2; they undergo the acrosome reaction on the zona pellucida and then transfer their binding to ZP3.

C. When a sperm reaches the oocyte and fuses with it, the cortical granules release proteins that digest portions of ZP2 and ZP3, making them nonfunctional and prevent polyspermy.

D. When a sperm reaches the oocyte and fuses with it, the cortical granules release proteins that digest ZP3 only, not ZP2 because ZP2 involve in the process of slow block to polyspermy.

Which of the above statements are correct?

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: 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: 12994

#Unit 1. Molecules and their Interaction Relevant to Biology

α-helix changes their configurations according to the environment then

a. when found in aqueous or plasm environment 

b. when found in membrane or hydrophobic environment

in the given condition interaction will be 

TLS Online TPP Program

#Question id: 12993

#Unit 1. Molecules and their Interaction Relevant to Biology

Out of these which of the following is true regarding the propensity of α-helix.

a. any amino acid which can take up desirable ϕ and ψ angle close to -57 and -47 will favour the formation of a α-helix

b. amino acid such a proline and glycine have lowest propensity will favour formation of α-helix.

c. if the resultant change in the value ΔΔG0 is positive then it will favour the formation of α-helix.

d. if the resultant change in the value ΔΔG0 is zero or close to zero then it will favour the formation of α-helix.

TLS Online TPP Program

#Question id: 12992

#Unit 1. Molecules and their Interaction Relevant to Biology

α-helix changes its configurations according to the environment then

a. membrane encompassing α-helix have nonpolar residue oriented toward the membrane lipid.

b. if α-helix is found in plasm then polar residue will be oriented toward the outside.

c. if α-helix is found in plasm then nonpolar residue will be present inside the core.

d.  membrane encompassing α-helix have polar residue oriented towards the membrane lipid.

Choose incorrect statement

TLS Online TPP Program

#Question id: 12991

#Unit 1. Molecules and their Interaction Relevant to Biology

Choose the correct statements

a. Secondary structures are stabilized by hydrogen bonds.

b. Hydrogen bond always formed between non bonded atoms.

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

d. Only dihedral angle changes during the formation of secondary structure while bond length remains unchanged