Class 3: Peptide Hormones

Question 1

Gonadotropins:

Answer 1

LH and FSH

Question 2

FSH:

Answer 2

(From Pituitary): In ovary, stimulates development of ovarian follicles; In testes, regulates function of Sertoli cells (somatic cells within the testes that support sperm development) in the seminiferous tubules (compartments in which male gametes grow)

Question 3

LH:

Answer 3

(From Pituitary): Secretion of steroid hormones from the gonads by binding to and stimulating steroidogenic cells (ovary & testes), regulates ovulation in females.

Question 4

GnRH

Answer 4

(From Hypothalamus) endocrine communication via blood vessels to the pituitary

Question 5

Exocytosis

Answer 5

delivery of the peptide hormone (or any other molecule) from out of the cell through secretory machinery (vesicles).

Question 6

Endoplasmic reticulum :

Answer 6

Organelle where translation of proteins that are destined to leave the cell occurs.

Question 7

Secreted protein

Answer 7

peptide hormones are secreted proteins that pass through the lipid bilayer and exit the cytoplasm to serve a function elsewhere in the cell.

Question 8

Membrane protein:

Answer 8

cell membranes consist of a lipid bilayer and membrane proteins which accomplish vital biological functions. The ones we focused on in class were membrane receptor proteins which serve as the connection between intracellular and extracellular activity.

Question 9

Differential gene expression

Answer 9

Only certain genes are transcribed in each cell type

Question 10

Ligand :

Answer 10

molecule that binds

Question 11

Steroid hormone receptor aka nuclear receptor:

Answer 11

Class of receptors: Androgen/ Estrogen/ Progesterone Receptors that consist of a DNA binding domain, a ligand binding domain (where T,E, P attach), and other “variable” factors. This receptor attached to the HRE (Hormone Response Element) & via a transcription factor begins transcription of DNA to RNA.

Question 12

Transmembrane domains:

Answer 12

Positions the receptor in the plasma membrane, this domain is actually in the lipid membrane (hydrophobic/ lipophilic)

Question 13

G-protein-coupled receptor:

Answer 13

Binds ligand (the peptide hormone); in the family: FSH-R, LH-R, GnRH-R

Question 14

G-protein :

Answer 14

proteins closely coupled to the receptor, and initiate the intracellular signal transduction events.

Question 15

Second messenger

Answer 15

Second messengers tend to be very small molecules. I.e. cAMP (Cyclic AMP)

Question 16

Kinase:

Answer 16

enzymes that add phosphate groups to their substrates.

Question 17

phosphorylation

Answer 17

the process of adding a phosphate group, phosphorylation changes the action of the protein

Question 18

Signal Transduction:

Answer 18

Peptide hormone “first messenger”, attaches to molecule on the cell membrane initiating a reaction that produces a “second messenger” on the inside of the cell or allows for release of second messenger from a storage site out into the cytoplasm.

Question 19

Basic Steps to Gonadotropin (LH/FSH) Induced Signaling:

Answer 19

1. Hormone Binds to the receptor (G-protein complex family) → activation of the G-protein
2. G-Protein activates Adenylate Cyclase (AC)
3. Activated AC generates Cyclic AMP (cAMP)
4. cAMP activates kinase protein kinase A (PKA) -which adds a phosphate group to the substrate ( phosphorylation).

Question 20

Basic Steps to GnRH Induced Signaling:

Answer 20

1. Hormone Binds to the receptor (G-protein complex family) → activation of the G-protein
2. G-Protein activates Phospholipase C (PLC)
3. Activated PLC generates second messenger IP3
4. IP3 attached to receptor on ER & induces endoplasmic reticulum to release Calcium
5. Calcium activates kinase activity (which adds a phosphate group to the substrate – phosphorylation.)