Exam 2 (bad)

Question 1

Types of Chemical Signaling

Answer 1

(a) Synaptic - chemical signaling, transfer of info from one neuron to another
(b) Paracrine - long-range transmission of chemical signals, requires secretion of chemical signals onto group of nearby target cells
(c) Endocrine - secretion of hormones into the bloodstream where they can affect targets anywhere in the body

Question 2

What are the advantages to chemical signaling?

Answer 2

specialization, propagation/amplification

Question 3

What is signal amplification?

Answer 3

Single individual reaction that can generate a much larger number of molecular products than number of molecules that initiate the reaction

Question 4

Benefits of signal amplification

Answer 4

Precise control of cell behavior (fast vs. slow), guarantees a response

Question 5

Cell impermeant molecules

Answer 5

Type of signaling molecule; doesn’t cross membrane, binds to receptors on PM (secreted molecules, most NT’s)

Question 6

Cell permeant molecules

Answer 6

type of signaling molecule, can freely cross PM to bind to intracellular receptors(hormones)

Question 7

Cell-associated molecules

Answer 7

type of signaling molecule, embedded permanently in PM surface, can only act on cells it is physically in contact with

Question 8

Channel-linked receptors

Answer 8

ligand-gated ion channels, receptor and transducing functions are part of the same protein –> chemical binds, channel opens

Question 9

Enzyme-linked receptors

Answer 9

extracellular binding site, intracellular domain is an enzyme, chemical binds, enzyme is functional and can generate an effector protein (ex: protein kinases that phosphorylate intracellular target proteins)

Question 10

G-protein coupled receptors

Answer 10

metabotropic receptors, regulate intracellular reactions via an intermediary (the G-protein)

Question 11

Heterotrimeric G protein

Answer 11

g-binding protein, 3 subunits (a, b, y)

Question 12

How do heterotrimeric G proteins work?

Answer 12

a binds to GTP or GDP, then can bind to b and y to form an inactive trimer -> extracellular signal binds, G-protein binds receptor and exchanges GDP for GTP -> causes a to dissociate and G-protein becomes active

Question 13

Monomeric G-proteins

Answer 13

(ex: Ras) inactive when GDP bound, active with GTP

Question 14

GEF proteins

Answer 14

Mediate GDP to GTP reaction

Question 15

GAP proteins

Answer 15

Terminate signal by hydrolysis of GTP to GDP

Question 16

Intracellular receptors

Answer 16

activated by cell-permeant molecules, most ultimately result in production of new mRNA and protein, receptor often bound to an inhibitor that dissociates upon ligand binding, which exposes a DNA binding site, so receptor moves into nucleus (for transcription and translation)

Question 17

Ca+ as a second messenger

Answer 17

1. Cell depol 2. voltage-gated Ca+ channels open 3. Ca+ floods in 4. synaptotagmin -> exocytosis