TLS Online TPP Program

#Question id: 1257


Following statements are regarding to protein kinase A which phosphorylates multiple intracellular target proteins expressed in different cell types.

A. Inactive PKA is a tetramer consisting of two regulatory (R) subunits and two catalytic (C) subunits.

B. Each R subunit contains a pseudo-substrate domain whose sequence resembles that of a peptide substrate and binds to the active site in the catalytic domain but is not phosphorylated; thus the pseudo-substrate domain inhibits the activity of the catalytic subunits.

C. active PKA is turned off by binding of cAMP Each R subunit has two distinct cAMP-binding sites, called CNB-A and CNB-B.

D. Binding of cAMP by an R subunit of PKA occurs in a cooperative fashion; that is, binding of the first cAMP molecule to CNB-B increases the Kd for binding of the second cAMP to CNB-A. Thus small changes in the level of cytosolic cAMP can cause proportionately large changes in the number of dissociated C subunits and, hence, in cellular kinase activity.

Which of the following statements are incorrect?

#Unit 4. Cell Communication and Cell Signaling
  1. A, B and C

  2. B and C

  3. C and D

  4. B only

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TLS Online TPP Program

#Question id: 4762

#Unit 8. Inheritance Biology

a semilethal allele is an example of which of the following extensions of mendelian genetics?

TLS Online TPP Program

#Question id: 4763

#Unit 8. Inheritance Biology

in a rare blood type referred to as the bombay phenotype, individuals are unable to attach the a or b antigens to their red blood cells. individuals that are homozygous recessive for gene "h" have the bombay phenotype and their blood type is type "o" regardless of their abo genotype. this is an example of what extension of mendelian inheritance?

TLS Online TPP Program

#Question id: 4764

#Unit 8. Inheritance Biology

Which of the following is the best example of overdominance?

TLS Online TPP Program

#Question id: 4765

#Unit 8. Inheritance Biology

The recessive mutant allele that causes cystic fibrosis is much more frequent in Caucasians population than in other world populations. Some scientists believe heterozygotes must have had a survival advantage during plagues such as cholera that occasionally swept through this population. What concept does this illustrate?

TLS Online TPP Program

#Question id: 4766

#Unit 8. Inheritance Biology

In soybeans, resistance to sudden death syndrome (SDS) is inherited as a dominant condition. In some cases, individuals that are not resistant to SDS (but whose parents were) can pass the trait on to their progeny. This is an example of which of the following?

TLS Online TPP Program

#Question id: 4767

#Unit 8. Inheritance Biology

Neurofibromatosis is a condition in humans which is generally inherited in a dominant fashion. Assuming this disorder is 90% penetrant, what is the chance that a single child born to a father with neurofibromatosis and a mother known not to carry the mutation will have the disorder?