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TLS Online TPP Program

#Question id: 13161

Which of the following mechanism depends on the activation of heterotrimeric G proteins?

#Unit 4. Cell Communication and Cell Signaling
  1. During actin filament formation, the inactive formin is activated when its Rho-binding domain (RBD) binds to membrane-bound active Rho-GTP, resulting in exposure of the formin’s FH2 domain, which can then nucleate the assembly of a new actin filament.
  2. Rod cells sense light with the aid of a light-sensitive rhodopsin which is coupled to transducin. On absorption of a photon, the retinal moiety of rhodopsin is immediately converted from the cis isomeric form to the all-trans isomeric form, causing a conformational change that allows rhodopsin to bind the α subunit of transducin.
  3. Ras proteins are “switch” proteins and not directly linked to cell-surface receptors. Ras activation is accelerated by a guanine nucleotide exchange factor (GEF), which binds to the Ras∙GDP complex, causing dissociation of the bound GDP.
  4. During the regulation of microfilament organization, Cdc42 act as molecular switches, inactive in the GDP-bound state and active in the GTP-bound state.
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TLS Online TPP Program

#Question id: 994

#Unit 1. Molecules and their Interaction Relevant to Biology

If the 16-carbon saturated fatty acid palmitate is oxidized completely to carbon dioxide and water (via the B-oxidation pathway and the citric acid cycle), and all of the energy-conserving products are used to drive ATP synthesis in the mitochondrion, the net yield of ATP per molecule of palmitate is:
TLS Online TPP Program

#Question id: 995

#Unit 1. Molecules and their Interaction Relevant to Biology

Saturated fatty acids are degraded by the stepwise  reactions of B oxidation, producing acetyl-CoA. Under aerobic conditions, how many ATP molecules would be produced as a consequence of removal of each acetyl-CoA?
TLS Online TPP Program

#Question id: 996

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following is (are) true of the oxidation of 1 mol of palmitate (a 16-carbon saturated fatty acid; 16:0) by the B-oxidation pathway, beginning with the free fatty acid in the cytoplasm?

1. Activation of the free fatty acid requires the equivalent of two ATPs.

2. Inorganic pyrophosphate (PPi) is produced.

3. Carnitine functions as an electron acceptor.

4. 8 mol of FADH2 are formed.

5. 8 mol of acetyl-CoA are formed.

6. There is no direct involvement of NAD+.
TLS Online TPP Program

#Question id: 997

#Unit 1. Molecules and their Interaction Relevant to Biology

Complete oxidation of 1 mole of which fatty acid would yield the most ATP?
TLS Online TPP Program

#Question id: 998

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following statements apply (applies) to the B oxidation of fatty acids?

1.  The process takes place in the cytosol of mammalian cells.

2.  Carbon atoms are removed from the acyl chain one at a time.

3.  Before oxidation, fatty acids must be converted to their CoA derivatives.

4.  NADP+ is the electron acceptor.

5.  The products of B oxidation can directly enter the citric acid cycle for further oxidation.
TLS Online TPP Program

#Question id: 999

#Unit 1. Molecules and their Interaction Relevant to Biology

The balanced equation for the degradation of CH3(CH2)10COOH via the B-oxidation pathway is: