lecture 4

Question 1

2 categories of cell communication

Answer 1

1. local
2. long distance (neuronal, endocrine)

Question 2

3 types of local cell-cell communication

Answer 2

1. gap junctions
   = direct cytoplasmic connections, adjacent cells
2. contact-dependent signals
   = interaction between membrane molecules on two cells
3. autocrine/paracrine signals
   = act on the same cell that secreted them!!!!

Paracrine signals are secreted by one cell and diffuse to adjacent cells

Question 3

long distance communication

Answer 3

hormones are secreted by endocrine glands or cells into the blood

Neurotransmitters

only target cells with the receptors for the hormone will respond to the signal

Question 4

4 classes of chemical signalling molecules

Answer 4

1. amino acids
2. amines
3. peptides or proteins
4. steroids

Question 5

amino acids example

Answer 5

glutamate, glycine, GABA

Question 6

amines example

Answer 6

dopamine, epinephrine, norepinephrine, seretonin

Question 7

peptides or proteins example

Answer 7

insulin, glucagon

Question 8

steroids example

Answer 8

estrogen, testosterone
(derived from cholesterol)

Question 9

receptor locations

Answer 9

can be intracellular signal receptors or cell membrane receptors

Question 10

4 categories of membrane receptors

Answer 10

1. Receptor-channel
2. Receptor-enzyme
3. G protein-coupled receptor
4. Integrin receptor

Question 11

Receptor-channel/Ligand-gated channels (describe)

Answer 11

ligand binding opens or closes the channel

Question 12

Receptor-enzyme/Enzyme-linked receptors (describe)

Answer 12

ligand binding to a receptor-enzyme activates an intracellular enzyme

Question 13

GPCR (describe)

Answer 13

ligand binding to a G protein coupled receptor opens an ion channel or alters enzyme activity

Question 14

Integrin receptor

Answer 14

ligand binds to integrin receptors and alters the cytoskeleton

Question 15

Give an overview of signal transduction

Answer 15

-Signal molecule bind to
-Receptor protein which activates
-Intracellular signal molecules which alter
-Target proteins which create a
-Response

Question 16

what do kinases do?

Answer 16

phosphorylate proteins

Question 17

phosphatases

Answer 17

dephosphorylate proteins

Question 18

Ca2+ signalling: 2 mechanisms

Answer 18

1. voltage gated channels
2. ligand gated channels/mechanically gated channels

Question 19

Calcium acts as an

Answer 19

intracellular messenger

calcium can also be released from stores by second messengers

Question 20

what are the two possible effects of Ca2+ in the cytosol increasing?

Answer 20

1. Calmodulin: alters protein activity
2. Other calcium binding: exocytosis and movement