Cell Signaling

Question 1

cell-surface receptor binding/ endocrine and paracrine signaling

Answer 1

extracellular signaling

Question 2

nuclear receptors

Answer 2

intracellular signaling

Question 3

molecular switches, signal integration

Answer 3

signaling mechanisms

Question 4

Intracellular signaling pathways can be activated by an extracellular signal molecule (T or F)

Answer 4

True

Question 5

Extracellular signal molecules can bind to only cell-surface receptors (T or F)

Answer 5

False, can also bind to intracellular receptors

Question 6

4 forms of intercellular signaling

Answer 6

1. Endocrine - hormones into bloodstream
2. Paracrine - into extracellular fluid locally
3. Synaptic - NTs electronically along axon
4. Contact-Dependent - cell-to-cell communication

Question 7

adrenaline, cortisol, estradiol, insulin, testosterone, thyroid

Answer 7

example of hormones

Question 8

epidermal GF, platelet-derived GF, nerve GF, histamine, nitric oxide

Answer 8

example of local mediators

Question 9

acetylcholine, GABA

Answer 9

example of neurotransmitters

Question 10

delta

Answer 10

example of contact-dependent signal molecule

Question 11

Contact-dependent signaling controls nerve-cell production in the fruit fly Drosophila (T or F)

Answer 11

True

Question 12

Extracellular signals always act fast (T or F)

Answer 12

False, can act slow too

Question 13

Animal cells rely on multiple extracellular signals (T or F)

Answer 13

True

Question 14

Various responses in various cells can be induced by the same signal molecule (T or F)

Answer 14

True

Question 15

GABA triggers smooth muscle relaxation in a blood-vessel wall (T or F)

Answer 15

False, nitric oxide does this

Question 16

Signal molecules that bind to nuclear receptors are usually small and hydrophobic (T or F)

Answer 16

True

Question 17

The steroid hormone cortisol acts by activating a transcription regulator (T or F)

Answer 17

True

Question 18

3 classes of cell-surface receptors

Answer 18

1. Ion-Channel-Coupled
2. G-Protein-Coupled
3. Enzyme-Coupled

Question 18

Tasks done by intracellular signaling proteins (4)

Answer 18

1. Relay
2. Amplify
3. Integrate
4. Distribute the Incoming Signal

Question 19

What are the two types of intracellular signaling proteins that act as molecular switches?

Answer 19

1. Signaling by protein phosphorylation
2. Signaling by GTP-Binding proteins

Question 20

Positive and negative feedback mechanisms exist in biological switching networks (T or F)

Answer 20

True

Question 21

Structure of G-Protein-Coupled Receptors

Answer 21

polypeptide chain that transverses the plasma membrane seven times with the cytoplasmic part of the receptor bind to a G protein inside the cell

Question 22

An activated G-protein disassembles into 2 signaling components (alpha and beta) (T or F)

Answer 22

True

Question 23

After activation, what happens to the G-protein alpha-subunit?

Answer 23

It switches itself off by hydrolyzing its bound GTP to GDP

Question 24

What happens in heart pacemaker cells?

Answer 24

A G Protein-linked receptor couples activation to K+ channel opening

Question 25

G Protein-linked receptors can cause release of second messenger signaling molecules (T or F)

Answer 25

True

Question 26

Cyclic AMP (cAMP) increase rapidly in response to an intracellular signal in nerve cells (T or F)

Answer 26

False, an extracellular signal

Question 27

What synthesizes cyclic AMP?

Answer 27

adenylyl cyclase

Question 28

What degrades cyclic AMP?

Answer 28

cyclic AMP phoshodiesterase

Question 29

What does adrenaline stimulate?

Answer 29

Glycogen breakdown in skeletal muscle cells

Question 30

What activates gene transcription?

Answer 30

A rise in cAMP concentration

Question 31

Phospholipase C activates two signaling pathways called?

Answer 31

1. Diacylglycerol 2. Inositol 1,4,5-trisphosphate (IP3)

Question 32

Cell Responses Mediated by Phospholipase C Activation (3)

Answer 32

1. Vasopressin 2. Acetylcholine (pancreas and smooth muscle) 3. Thrombin

Question 33

What does fertilization of an egg by a sperm trigger?

Answer 33

An increase in cytosolic Ca++

Question 34

What does calcium binding do?

Answer 34

Changes the shape of the calmodulin protein

Question 35

What activates the Ras protein?

Answer 35

Docking intracellular signaling proteins on an activated receptor tyrosine kinase

Question 36

What does Ras activate?

Answer 36

a MAP-kinase signaling pathway

Question 37

What does receptor tyrosine kinases (RTKs) activate?

Answer 37

the PI-3-kinase-Akt signaling pathway

Question 38

Activated Akt promotes cell death (T or F)

Answer 38

False, cell survival

Question 39

Growth factor binding to enzyme receptor kinases can stimulate cells to grow (T or F)

Answer 39

True

Question 40

Both G Protein couples receptors and receptor tyrosine kinases activate multiple intracellular signaling pathways (T or F)

Answer 40

True

Question 41

The Notch receptor is NOT a transcription regulator (T or F)

Answer 41

False, it is

Question 42

In plants, the ethylene signaling pathway turns on genes by removing what?

Answer 42

inhibition

Question 43

Intracellular signaling proteins can integrate multiple signals (T or F)

Answer 43

True