Biochemistry: Lecture 1

Question 1

A newly discovered hormone is found to be derived from cholesterol. According to the classification provided in the source, this hormone would be best categorized as a lipid-derived hormone and would likely belong to which solubility group?

Answer 1

Group 1
Water insoluble proteins

Question 2

Which of the following characteristics is typically associated with water-insoluble hormones as described in the provided text?
a) Short plasma half-life
b) Binding to plasma membrane receptors
c) Requirement of transport proteins in the blood
d) Generation of second messengers upon receptor binding

Answer 2

Requirement of transport proteins in the blood

Question 3

The mechanism of action of steroid hormones primarily involves which of the following steps, according to the source?
a) Activation of membrane-bound enzymes
b) Direct modulation of gene transcription
c) Rapid alteration of ion channel permeability
d) Production of intracellular second messengers

Answer 3

b) Direct modulation of gene transcription

Question 4

According to the source, the hormone-receptor complex formed by a water-insoluble hormone acts as which of the following?
a) A second messenger
b) An active protein kinase
c) An inducible transcription factor
d) A ligand for membrane-bound receptors

Answer 4

D

Question 5

Which of the following is a general characteristic of water-soluble hormones as outlined in the provided document?
a) They readily cross the plasma membrane to bind intracellular receptors.
b) Their receptors are typically located on the plasma membrane.
c) They primarily exert their effects by directly binding to DNA.
d) They generally have a long plasma half-life due to protein binding.

Answer 5

B

Question 6

Activation of adenylyl cyclase by a hormone receptor complex leads to an increase in the intracellular concentration of which second messenger? Which enzyme does this second messenger subsequently activate?

Answer 6

Increase in cAMP and activates protein kinase A

Question 7

Epinephrine, glucagon, and follicle-stimulating hormone (FSH) are listed in the source as examples of hormones that utilize which signaling pathway?

Answer 7

CAMP pathway

Question 8

An increase in intracellular cGMP levels, as described in the source, is typically mediated by the activation of which enzyme?

Answer 8

Guanylyl andenyl
Activates CGMP Protein kinase

Question 9

Atrial natriuretic peptide and estradiol (estrogen) are given as examples of hormones that can utilize which second messenger system, according to the provided text?

Answer 9

CGMP pathway

Question 10

Phospholipase C (PLC) plays a key role in the signaling pathway of several hormones. According to the source, what are the two main second messengers generated by PLC?
What is the primary action of inositol 1,4,5-triphosphate (IP3) in this pathway?

Answer 10

DAG and IP3

IP3 binds to the receptor in ER —> releases Ca2+ —> Ca2+ binds to DAG to active protein kinase C

Question 11

Angiotensin II, oxytocin, and vasopressin are listed in the source as examples of hormones that utilize which signaling pathway involving a membrane-bound enzyme?

Answer 11

Phospholipase C

Question 12

Some hormone receptors possess intrinsic tyrosine kinase activity. According to the source, what is the immediate consequence of hormone binding to this type of receptor?

Answer 12

Autophorsplyation

Question 13

Catecholamines are derived from which amino acid and belong to which solubility group of hormones, according to the source?

Answer 13

Catacholamines — epinephrine — belong to Water soluble hormones.

Question 14

Diacylglycerol (DAG) and calcium ions, produced in the phospholipase C pathway, act together to activate which specific enzyme?

Answer 14

Protein kinase C

Question 15

The source mentions that in some cases where the receptor-associated enzyme is guanylyl cyclase, hormone binding can result in decreased [cGMP]. What enzymatic activity would be responsible for this decrease?

Answer 15

cGMP Phosphodieterase

Question 16

In the context of tyrosine kinase receptors, what is meant by “autophosphorylation” as described in the source?

Answer 16

Once a hormone binds to the TK receptor, it automatically phosphorylates the enzyme or activates any PK’s.

Question 17

Calcitriol is mentioned as a lipid-derived hormone. According to the source, from which precursor is calcitriol derived? To which solubility group does it belong?

Answer 17

Vitamin D and water insoluble hormone

Question 18

Hormones control a wide range of physiological processes. List five specific roles of hormones mentioned in the provided text.

Answer 18

Blood pressure
Electrolyte balance
Growth and development
Sexual differentiation and reproduction
Hunger/ satiety
Digestion

Question 19

List your water insoluble hormone and soluble hormones

Answer 19

Water insoluble:
Steroid hormones
Retinoid
Thyroid
Eicosanoids
Calcitriol
_____________________

Water soluble:
Catecholamines
Peptides, proteins, glycoproteins

Question 20

Regarding group 1 and group 2 proteins, state the receptor, mediator and whether a transport protein is needed for each.

Answer 20

Group 1:
Receptor : intracellular
Mediator: receptor - hormone complex
Transport: Yes

Group 2:
Receptor: plasma membrane
Mediator: 2nd messenger
Transport: No

Question 21

Discuss the mechanism of action for water insoluble hormones.

Answer 21

1. Hormone Receptor binding
2. Hormone relocated in nucleus
3. Hormones binds to DNA
4. Transcription
5. Translation

Question 22

Discuss the mechanism of action for water soluble hormones.

Answer 22

1. Receptor binding
2. 2nd messanger Transport
3. Signal cascading
4. Cellular response
5. Biological response