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TLS Online TPP Program

#Question id: 163

Which of the following statements about cystine is correct?

#Unit 1. Molecules and their Interaction Relevant to Biology

  1. Cystine forms when the —CH2—SH R group is oxidized to form a —CH2—S—S—CH2— disulfide bridge between two cysteines.

  2. Cystine is an example of a nonstandard amino acid, derived by linking two standard amino acids.

  3. Cystine is formed by the oxidation of the carboxylic acid group on cysteine.

  4. Cystine is formed through a peptide linkage between two cysteines.

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TLS Online TPP Program

#Question id: 13160

#Unit 4. Cell Communication and Cell Signaling

According to the Switching mechanism, monomeric G proteins exist in two states. Match the following states (Column I) with correct mechanism (Column II).

Column I

Column II

A. “ON” state 

i. switch I and switch II, are bound to the terminal γ phosphate of GTP through interactions with the backbone amide groups of conserved threonine and glycine residues.

B. “OFF” state

ii. GTPase-activating proteins

 

iii. guanine nucleotide exchange factor

 

iv. Due to the removal of the γ phosphate by GTPase-catalyzed hydrolysis causes switch I and switch II to relax into a different conformation

TLS Online TPP Program

#Question id: 13161

#Unit 4. Cell Communication and Cell Signaling

Which of the following mechanism depends on the activation of heterotrimeric G proteins?
TLS Online TPP Program

#Question id: 13162

#Unit 4. Cell Communication and Cell Signaling

In the amoeba Dictyostelium discoideum, cAMP acts as an extracellular signalling molecule and binds to and signals via a G protein–coupled receptor; it is not a second messenger. Amoeba cells were transfected with genes encoding two fusion proteins: a Gα fused to cyan fluorescent protein (CFP), and a Gβ fused to yellow fluorescent protein (YFP). CFP normally fluoresces 490-nm light; YFP, 527-nm light. In which conditions fluorescence
energy transfer occur from CFP to YFP?
TLS Online TPP Program

#Question id: 13163

#Unit 4. Cell Communication and Cell Signaling

Following statements are regarding to the interaction between β2-adrenergic receptor and G- protein.
TLS Online TPP Program

#Question id: 13164

#Unit 4. Cell Communication and Cell Signaling

Match the following.

Column IColumn IIColumn III
A. G Protein–Coupled Receptors That Activate PDEi. cAMPa. Increase in conversion of glycogen to glucose
B. G Protein–Coupled Receptors That Activate Adenylyl Cyclaseii. cGMPb. Hyperpolarization or depolarization of photoreceptor membrane
C. G Protein–Coupled Receptors That inhibit Adenylyl Cyclaseiii. DAGc. activates genes necessary for cell division
D. G Protein–Coupled Receptors That Trigger Elevations in Cytosolic and Mitochondrial Calcium
d. increase in K+ permeability hyperpolarizes the membrane

Which one of the following is correct?
TLS Online TPP Program

#Question id: 13165

#Unit 5. Developmental Biology

One of the main ways by which the insulin signaling pathway might function to lower longevity is to activate mTORC1, a protein kinase complex that promotes the translation of mRNA into proteins in response to nutrients and hormones, select incorrect statement;