Cell Communication

Question 1

Type 1 diabetes vs type 2 diabetes

Answer 1

1-insulin deficiency

2-insulin resistance

Question 2

4 components of cell signaling

Answer 2

signaling cell
signal molecule
target cell
receptor protein

Question 3

Endocrine signaling

Answer 3

Signals secreted into bloodstream and distributed throughout the body

Question 4

Examples of endocrine signaling

Answer 4

Adrenaline (secreted via adrenal gland to increase BP, HR, and metabolism)

Insulin (secreted protein via beta cells of pancreas to stimulate glucose uptake and protein/lipid synthesis)

Question 5

Paracrine signaling

Answer 5

Signals released by cells into the extracellular medium to act LOCALLY.

Doesn’t involve bloodstream.

Affects same location tissue

Question 6

Autocrine signaling

Answer 6

Signal released by cell and binds to autocrine receptor on same cell

Signaling and target cell are the same

Question 7

Examples of paracrine signaling

Answer 7

Epidermal growth factor (Protein thats secreted by cells to stimulate epidermal and other cell type proliferation)

Nitric oxide (nerves and endothelial cells secrete gas as a vasodilator and regulate nerve activity)

Question 8

Neuronal signaling

Answer 8

Neuronal signals are transmitted along axons to remote target cells.

Synapse allows presynaptic neuron to pass signal to postsynaptic cell

Question 9

Example of neuronal signaling

Answer 9

Acetylcholine (from nerve terminal that allows excitatory neurotransmitter at many nerve-muscle synapses and in CNS)

Question 10

Contact dependent cell signaling

–>What helps with intercellular connections?

Answer 10

Requires cells to be in direct membrane to membrane contact with each other

Gap junctions can be used to establish intercellular connection to directly connect cytoplasm of two cells.

Question 11

What may happen if a cell is deprived of survival signals?

Answer 11

apoptosis

Question 12

T/F the same signal molecule can induce different responses in different cells

Answer 12

T

Example:acetylcholine

Question 13

Extracellular signals can act rapidly or slowly depending on if they are

Answer 13

Non-genomic or genomic

Question 14

Genomic actions

Answer 14

Alters transcription of a protein

Question 15

Non-genomic actions

Answer 15

Alters non-genomic actions of an existing protein

Question 16

What are the 3 major cell-surface receptors

Answer 16

Ion channel coupled receptors

G protein coupled receptors

Enzyme coupled receptors

Question 17

Ion coupled receptors

• ->where are they located
• ->example

Answer 17

Cell surface

Acetylcholine-activated Na+ channel in skeletal muscle

Question 18

Ion channel coupled receptors convert chemical signals to

Answer 18

electrical signal

When ligand of receptor is bound, altered cell membrane potential results

• ->Cation influx or anion efflux=depolarization
• ->Anion influx or cation efflux= hyperpolarization

Question 19

What are some common ways proteins are regulated (2)?

Answer 19

Reversible phosphorylation

Binding to GTP

Question 20

Explain relation of transduced signals and amplification of signals

Answer 20

Cell receptors transduce signal (first messenge) which then get amplified (via second messengers)

Question 21

Give overview of receptor transducing extracellular signals that get amplified

Answer 21

First messenger binds to cell surface receptor

Enzyme interacts with receptor to amplify second messengers

Signaling proteins integrate amplified signals

Effector proteins help relay signals

There’s altered function in the cell

Question 22

Give example of first messenger and its ultimate goal

Answer 22

Adrenaline binds to adrenergic receptor to breakdown glycogen to glucose

OR

Adrenaline can spur contraction of heart

Question 23

G protein coupled receptor

• ->Located where
• ->structure of G protein

Answer 23

-Cell surface

• Has 7 transmembrane domains
• Heterotrimeric (alpha, beta, gamma subunits)

Question 24

Give some examples that GPCR can interact with as signal molecules

AKA

Answer 24

AKA first messengers

Adrenaline, Achl, Vasopressin

Question 25

Name some second messangers GPCR is involved with

Answer 25

cAMP
IP3
Calcium
DAG

Question 26

Name some signaling proteins that GPCR is involved with

Answer 26

PKA
CaM Kinase
PKC

Question 27

When is GPCR active/inactive

Answer 27

inactive-GDP w/alpha subunt

active-GTP w/alpha subunit

Question 28

Role of alpha subunit with GPCR

Answer 28

Exchanges GDP for GTP to activate receptor

Question 29

T/F Only activated alpha subunit (w/GTP) can regulate target proteins. Not beta/gamma subunit

Answer 29

False

Alpha subunit with GTP and free beta/gamma subunit can regulate target proteins

Question 30

How GPCR is activated/inactivated

Answer 30

Activated-binds to GTP

Inactivated-alpha subunit is hydrolyzed to GDP by alpha’s INTRINSIC GTPase activity to reconnect with beta/gamma subunits

Question 31

How are G proteins defined?

Answer 31

By alpha subunit

alpha(s)-increase adenylyl cyclase activtiy
alpha(q)-increase phospholipase C activiy

Question 32

2 Major categories of GPCR

Answer 32

• Those that regulate ion channels

- Those that stimulate intracellular membrane-bound enzyme activity

Question 33

Explain GPCR with ion channels

Answer 33

Achl receptor is activated

alpha subunit of GPCR is activated
gamma/beta subunit regulates K+ ion channel to allow hyperpolarization

Question 34

What second messenger does adenylyl cyclase interact with?

Phospholipase C?

Answer 34

• cAMP

- IP3 and DAG

Question 35

[intracellular cAMP] is determined by

Answer 35

The activity of adenylyl cyclase (synthesizes cAMP)
AND
Phosphodiesterase (degrades cAMP)

Question 36

Activity of PKA depends on what

Answer 36

[cAMP]

Question 37

Give overview of GPCR rxn with alpha^s subunit

Answer 37

Signal molecule (adrenaline, Achl, Vasopressin) activates GCPR and alpha subunit triggers adenylyl cyclase which makes cAMP Phosphodiesterase will degrade some cAMP. cAMP will activate PKA which ultimately alters some cell function.