Question

In: Biology

40. unlike membrane G protein couple receptors some ligand gated ion channels can be directly activated...

40. unlike membrane G protein couple receptors some ligand gated ion channels can be directly activated by cytosolic second messengers.

a. true
b. false

2. Arrestin-mediated internalization of GPCRs terminates the GPCR signaling. The binds of arrestin is facilitated by ____ .
a. Inactivation of GPCR
b. GPCR in endosome
c. G-protein-couple receptor kinase (GRK)-mediated phosphorylation
d. dephosphorylation of GPCR

12. Checkpoints halt the progress of the cell cycle when:
a. The DNA cannot be repaired in cancer cells
b. All of the choices are correct
c. The chromosome are not properly aligned during the interphase
d. The chromosomal DNA is damaged in normal cells
e. There is an abnormal number of chromosomes in the telophase

Expert Solution

40.

TRUE.

Calcium channels in ER open in response to IP3, second messenger in the cytoplasm.

2.

The correct option is.:

c. G-protein-couple receptor kinase (GRK)-mediated phosphorylation. These kinases are Serine/Threonine kinases.

other options are incorrect because:

Binding of Arrestin leads to inactivation but inactivation does not lead to Arrestin binding.

After Arrestin binding GPCR are pulled into endosomes.

Not dephosphorylation but phosphorylation leads to Arrestin binding.

12.

The correct option is:

d. The chromosomal DNA is damaged in normal cells.

The protein p53 stops the cell cycle and the cell may die.

Other options are incorrect:

The DNA cannot be repaired in cancer cell and even after that cell continues to divide.

The chromosome are not properly aligned during the interphase is incorrect because chromosomes are loosely packed in interphase but are tightly packed at metaphase.

gladiator answered 2 years ago

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