Question 1

The insulin receptor is in what class of tyrosine kinase receptors?

Accepted Answer

The insulin receptor belongs to Class II tyrosine kinase receptors, which have a 2a2b tetrameric structure.

Question 2

The hydrolysis of PIP₂ by phospholipase C-β yields what membrane-soluble secondary messenger?

Accepted Answer

The hydrolysis of PIP2 by phospholipase C-β produces diacylglycerol (DAG) as a membrane-soluble secondary messenger.

Question 3

Nitroglycerine is a potent ____ because of the release of ____.

Accepted Answer

Nitroglycerine is a potent vasodilator due to the release of nitric oxide, which relaxes smooth muscle in blood vessels and leads to dilation.

Question 4

All are components of the G-protein-coupled receptors (GPCRs) hormone signal transduction unit EXCEPT:

Accepted Answer

The answer of All are components of the G-protein-coupled receptors...

Question 5

A specific GTPase-activating protein (GAP) binds to and activates:

Accepted Answer

The question specifically mentions a GAP (GTPase-activating protein), which is known to activate the GTPase activity of specific GTPases, including Ras. Therefore, the correct answer is D: the GTPase activity of the Ras protein.

Question 6

All are domains of receptor tyrosine kinase EXCEPT:

Accepted Answer

Receptor tyrosine kinase domains include a glycosylated extracellular receptor-binding domain, a single transmembrane α-helix, an intracellular tyrosine kinase domain, and a regulatory domain with phosphorylation sites. Adenylyl cyclase activity domain is not a domain of receptor tyrosine kinase.

Question 7

All are unifying features of polypeptide hormones EXCEPT that they are:

Accepted Answer

Polypeptide hormones are synthesized as inactive preprohormones, but they are activated to hormones by proteolytic cleavage, not phosphorylation. The other options are all true unifying features of polypeptide hormones.

Question 8

The binding of hormone to G-protein coupled receptor stimulates the sequence:
A.binding of Gα (GTP) activates adenylyl cyclase
B.Gα(GTP) dissociates and re-associates with Gβγ
C.rapid exchange of GDP for GTP on Gα
D.GTPase of Gα hydrolyzes GTP to GDP
E.Gα dissociates from Gβγ

Accepted Answer

The correct sequence after a hormone binds to a G-protein coupled receptor is: rapid exchange of GDP for GTP on Gα (C), Gα dissociates from Gβγ (E), binding of Gα (GTP) activates adenylyl cyclase (A), GTPase of Gα hydrolyzes GTP to GDP (D), and Gα(GTP) dissociates and re-associates with Gβγ (B).

Question 9

How does extracellular hormone binding activate intracellular tyrosine kinase activity?

Accepted Answer

When the extracellular hormone binds to the receptor, this causes a conformational change that results in the oligomeric association of the receptors. This association then leads to auto-phosphorylation of tyrosine kinase domains within the cytoplasmic region of the receptor, leading to its activation. This activation then initiates a signaling cascade of downstream effectors, ultimately resulting in a cellular response.

Question 10

The second messenger produced from the hydrolysis of PIP₂ that activates the increase of Ca⁺⁺ concentrations in the cytoplasm is:

Accepted Answer

The second messenger produced from the hydrolysis of PIP₂ that activates the increase of Ca⁺⁺ concentrations in the cytoplasm is inositol-1,4,5-trisphosphate (IP₃). The hydrolysis of PIP₂ by phospholipase C (PLC) produces two second messengers: DAG and IP₃. While DAG activates protein kinase C (PKC), IP₃ releases stored Ca⁺⁺ from the endoplasmic reticulum leading to an increase in cytoplasmic Ca⁺⁺ concentrations.

Question 11

The amount of cAMP generated in the cytoplasm is dependent on the:

Accepted Answer

The amount of cAMP generated in the cytoplasm is dependent on the activity of adenylyl cyclase, which catalyzes the conversion of ATP to cAMP, as well as the activity of phosphodiesterase, which breaks down cAMP. Additionally, the length of time the GTP remains bound to the Gα-protein is also a factor in determining the amount of cAMP generated, making it necessary to choose all of the above (D).

Question 12

G-proteins are involved in directly mediating the activity of the following EXCEPT:

Accepted Answer

G-proteins directly mediate the activity of adenylyl cyclase, phospholipase C-β, and ion channels, but not calmodulin. Calmodulin is a calcium-binding messenger protein, not directly activated by G-proteins.

Question 13

Which of the following doe NOT correctly pair a hormone with its function?

Accepted Answer

ACTH (adrenocorticotropic hormone) stimulates the production and release of cortisol from the adrenal cortex. It does not play a role in promoting the production of thyroxine, which is regulated by thyroid-stimulating hormone (TSH).

Question 14

Receptor tyrosine kinases have been called ____ as a result of their ____ and ____.

Accepted Answer

Receptor tyrosine kinases (RTKs) are membrane-associated enzymes that are activated by binding of extracellular ligands. Upon ligand binding, RTKs undergo conformational changes that promote homo- or hetero-dimerization, leading to trans-autophosphorylation of tyrosine residues in the intracellular domain of the receptor. This activates the kinase activity of RTKs, which phosphorylate downstream signaling proteins and initiate intracellular signaling cascades. The term "allosteric enzyme" describes enzymes that undergo conformational changes upon binding of a ligand at a site other than the active site; this term is appropriate for the activation of RTKs by ligand binding. The term "oligomeric interactions" describes how RTKs can form complexes or oligomers upon ligand binding, which is also characteristic of this class of receptors.

Question 15

Steroid hormones, such as glucocorticoids, effect their action by:

Accepted Answer

The answer of Steroid hormones, such as glucocorticoids, effect their...

Question 16

In G-proteins, binding of GTP causes which of the following to occur?

Accepted Answer

When GTP binds to G-proteins, it causes a conformational change in the Gα subunit, leading to its dissociation from the Gβγ dimer, which can then interact with downstream effectors. This is known as Gα activation. Choice A is incorrect because Gβ and Gγ subunits do not associate with receptor tyrosine kinases upon GTP binding. Choice C is incorrect because GTP does not phosphorylate Gα. Choice D is incorrect because guanylation of Gβ does not promote activation of Gα.

Question 17

Each of the following statements is true EXCEPT:

Accepted Answer

Progesterone is not a polypeptide hormone but a steroid hormone.

Question 18

G-proteins are associated with which receptor superfamily?

Accepted Answer

G-proteins are associated with the 7-transmembrane segment (7-TMS) receptor superfamily, which includes receptors for various signaling molecules such as neurotransmitters, hormones, and cytokines. These receptors are characterized by their seven transmembrane domains and the ability to activate G-proteins upon ligand binding, leading to downstream signaling cascades.

Question 19

Hormones and other signal molecules bind with ____ affinities to their receptors and are produced at concentrations ____ their K_D values.

Accepted Answer

The answer of Hormones and other signal molecules bind with...

Question 20

All are enzymes in the enzyme cascade for activation of glycogen phosphorylase EXCEPT:

Accepted Answer

Hormone sensitive lipase is not a part of the enzyme cascade for activation of glycogen phosphorylase. The correct cascade includes adenylyl cyclase, protein kinase A, phosphorylase kinase, and ultimately glycogen phosphorylase itself.

Quiz 32: The Reception and Transmission of Extracellular Information

The insulin receptor is in what class of tyrosine kinase receptors?

The hydrolysis of PIP₂ by phospholipase C-β yields what membrane-soluble secondary messenger?

Nitroglycerine is a potent because of the release of .

All are components of the G-protein-coupled receptors (GPCRs) hormone signal transduction unit EXCEPT:

A specific GTPase-activating protein (GAP) binds to and activates:

All are domains of receptor tyrosine kinase EXCEPT:

All are unifying features of polypeptide hormones EXCEPT that they are:

The binding of hormone to G-protein coupled receptor stimulates the sequence: A.binding of Gα (GTP) activates adenylyl cyclase B.Gα(GTP) dissociates and re-associates with Gβγ C.rapid exchange of GDP for GTP on Gα D.GTPase of Gα hydrolyzes GTP to GDP E.Gα dissociates from Gβγ

How does extracellular hormone binding activate intracellular tyrosine kinase activity?

The second messenger produced from the hydrolysis of PIP₂ that activates the increase of Ca⁺⁺ concentrations in the cytoplasm is:

The amount of cAMP generated in the cytoplasm is dependent on the:

G-proteins are involved in directly mediating the activity of the following EXCEPT:

Which of the following doe NOT correctly pair a hormone with its function?

Receptor tyrosine kinases have been called as a result of their and .

Steroid hormones, such as glucocorticoids, effect their action by:

In G-proteins, binding of GTP causes which of the following to occur?

Each of the following statements is true EXCEPT:

G-proteins are associated with which receptor superfamily?

Hormones and other signal molecules bind with affinities to their receptors and are produced at concentrations their K_D values.

All are enzymes in the enzyme cascade for activation of glycogen phosphorylase EXCEPT:

Quiz 32: The Reception and Transmission of Extracellular Information

The insulin receptor is in what class of tyrosine kinase receptors?

The hydrolysis of PIP2 by phospholipase C-β yields what membrane-soluble secondary messenger?

Nitroglycerine is a potent ____ because of the release of ____.

All are components of the G-protein-coupled receptors (GPCRs) hormone signal transduction unit EXCEPT:

A specific GTPase-activating protein (GAP) binds to and activates:

All are domains of receptor tyrosine kinase EXCEPT:

All are unifying features of polypeptide hormones EXCEPT that they are:

The binding of hormone to G-protein coupled receptor stimulates the sequence: A.binding of Gα (GTP) activates adenylyl cyclase B.Gα(GTP) dissociates and re-associates with Gβγ C.rapid exchange of GDP for GTP on Gα D.GTPase of Gα hydrolyzes GTP to GDP E.Gα dissociates from Gβγ

How does extracellular hormone binding activate intracellular tyrosine kinase activity?

The second messenger produced from the hydrolysis of PIP2 that activates the increase of Ca++ concentrations in the cytoplasm is:

The amount of cAMP generated in the cytoplasm is dependent on the:

G-proteins are involved in directly mediating the activity of the following EXCEPT:

Which of the following doe NOT correctly pair a hormone with its function?

Receptor tyrosine kinases have been called ____ as a result of their ____ and ____.

Steroid hormones, such as glucocorticoids, effect their action by:

In G-proteins, binding of GTP causes which of the following to occur?

Each of the following statements is true EXCEPT:

G-proteins are associated with which receptor superfamily?

Hormones and other signal molecules bind with ____ affinities to their receptors and are produced at concentrations ____ their KD values.

All are enzymes in the enzyme cascade for activation of glycogen phosphorylase EXCEPT:

The hydrolysis of PIP₂ by phospholipase C-β yields what membrane-soluble secondary messenger?

Nitroglycerine is a potent because of the release of .

The second messenger produced from the hydrolysis of PIP₂ that activates the increase of Ca⁺⁺ concentrations in the cytoplasm is:

Receptor tyrosine kinases have been called as a result of their and .

Hormones and other signal molecules bind with affinities to their receptors and are produced at concentrations their K_D values.