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TLS Online TPP Program

#Question id: 5683

There may be an important connection between sperm translocation and capacitation. Which of the following option is correct explanation of above statement?

#Unit 5. Developmental Biology

  1. The influx of bicarbonate ions (and possibly other ions) alkalinizes the sperm, raising its pH.

  2. before entering the ampulla of the oviduct, the uncapacitated sperm bind actively to the membranes of the oviduct cells in the narrow passage (the isthmus) preceding it.  This binding is temporary and appears to be broken when the sperm become capacitated.

  3. The cholesterol efflux from the sperm cell membrane is thought to change the location of its “lipid rafts,” isolated regions that often contain receptor proteins that can bind the zona pellucida and participate in the acrosome reaction.

  4. Capacitation is a transient event but translocation is not.

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TLS Online TPP Program

#Question id: 733

#Unit 1. Molecules and their Interaction Relevant to Biology

Which one of the statements on protein conformation, detailed below is INCORRECT?
TLS Online TPP Program

#Question id: 732

#Unit 1. Molecules and their Interaction Relevant to Biology

Ramachandran plots can help increase the accuracy of models derived from x-ray crystallography data. The plot below was created by measuring phi, and psi for each amino acid residue in a 2.2 A resolution crystal structure. In the plot, which excludes Gly and Pro residues, selected residues (dots) are numbered 1 through 5.

Which of the following statements can be correctly stated for this plot in reference to selected residues?

A. Residues 1 and 3 are in either B sheets

B. residue 2 is in a right-handed a helix, and residue 4 is in a left-handed a helix.

C. If residue 5 were Gly, it might be in an acceptable position in the plot
TLS Online TPP Program

#Question id: 731

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following structure is mentioned in the given Ramachandran plot
TLS Online TPP Program

#Question id: 729

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following is correct about the collagen triple-helix domain

a. is rich in glycine.                             b. is rich in proline.

c. is rich in hydroxyproline.                d. is an alpha helix.
TLS Online TPP Program

#Question id: 728

#Unit 1. Molecules and their Interaction Relevant to Biology

Match the following tile peaks with corresponding circular dichroism spectra

A. Alpha helix

I. negative bands at 222 nm and 208 nm and a positive one at 190 nm.

B. Beta sheet

II. negative band at 218 nm and a positive one at 196 nm.

C. Random coil

III. positive band at 212 nm and a negative one around 195 nm.

TLS Online TPP Program

#Question id: 727

#Unit 1. Molecules and their Interaction Relevant to Biology

26-residue peptide composed of alanine and leucine shows a circular dichroism (CD) spectrum characteristic of α-helix at 50°C in 5 mM phosphate buffer at pH 7.4. When the peptide solution is cooled gradually to 25°C, and the CD spectra are recorded at different temperatures, the most likely observation will be that