Question

Question 15:

Which of the following statements is false?

A. Mitotic Cdk must be phosphorylated by an activating kinase (Cak) before it is active.

B. Phosphorylation of mitotic Cdk by the inhibitory kinase (Wee1) makes the Cdk inactive, even if it is phosphorylated by the activating kinase.

C. Active M-Cdk phosphorylates the activating phosphatase (Cdc25) in a positive feedback loop.

D. The activating phosphatase (Cdc25) removes all phosphates from mitotic Cdk so that M-Cdk will be active.

Question 18:

Which of these describes a Holliday junction?

A. A section of DNA where base pairing is not exact.

B. one strand of DNA containing genetic material from two different chromosomes.

C. An interaction of two strands of DNA from homologous chromosomes.

D. A three stranded DNA structure where single stranded DNA has invaded a double helix.

Question 19:

Which of the following statements about integrins is FALSE?

A. Integrins use adaptor proteins to interact with the microtubule cytoskeleton.

B. Integrins can switch to an activated state by binding to an extracellular matrix molecule.

C. Integrins can switch to an activated state by binding to an intracellular protein.

D. An activated integrin molecule takes on an extended conformation

Question 20:

Cadherin proteins____

A. create an electrical and metabolic coupling between epithelial cells.
B. link epithelial cells together by binding to similar cadherins in adjacent epithelial cells.
C. allow ions and small molecules to pass from one cell to another.
D. anchor epithelial cells to the basal lamina.

Answer 1

15)Ans. All Options are correct except D) is FALSE because activators phosphatase(cdc25) remove not all phosphate ,it removes only inhibitory phosphate added by wee1 kinase.

18)Ans. Holiday junction describe recombination between two homologous double stranded molecules,those with identical or nearly identical sequence.so option C) is correct.

19)Ans. Integrin are the transmembrane protein act as cell to matrix adhesion molecule.so in above option only option D) is FALSE because integrin is the transmembrane protein it never get extend their confirmation either it's activated or not.

20)Ans. Cadherin proteins are cell adhesion molecule so option B) is correct it links the epithelial cells together by binding similar cadherins in adjacent epithelial cells.