Lecture 20: Signal Transduction

Question 1

Effects of steroids on gene expression

Answer 1

Increases gene expression at the level of DNA transcription

Question 2

Steroids pathway/info

Answer 2

• Resides in cytoplasm –> nucleus bound to dna –> bound to proteins
• intracellular receptors
• increase gene expression
• Takes hours or days (slow)

Question 3

Gated Ion channels

Ligand

Voltage

Answer 3

Ligand:
-Binding of neurotransmitter causes channels to open and ions to rush through channel = altering membrane potentials or inhibiting nerve impulses

Voltage:
-Responds to change in voltage (Na+/K+ ATPASE)

Question 4

Tyrosine Kinase (Receptor enzyme)

Answer 4

-Insulin receptor

Intracellular effectors:

• Insulin receptor substrates = IRS 1-4
• Various adaptors
• Enzyme effectors

Cellular responses:

• Increased glucose uptake
• Regulation of transcription
• Activation of enzymes
• Covalent modification
• Increased enzyme synthesis

Question 5

Secondary messenger system:

Nitric Oxide (NO)

Answer 5

1) NO = signaling molecule which activated guanylate cyclase (NO in endothelial cell)
2) Guanylate cyclase binds to signals outside the cell and = cGMP inside the cell
3) Second messenger = cGMP
4) cGMP = smooth muscle relaxation, platelet aggregation, visual system, vasodilation

(NO can be produced by antihypertensive drugs like NITROPRUSSIDE and NITROGLYCERIN)

-(Acetylcholine, phopholipase c, IP3, rise in Ca+)

Question 6

What is second messenger?

Answer 6

Hormone or ligand that causes the concentration of another molecule to change inside the cell

Question 7

Other ways NO can be produced

Answer 7

Antihypertensive drugs (Nitoprussides, nitroglycerin)