Cell bio Chapter 15

Question 1

Yeast respond to mating factors by forming

Answer 1

Schmoos

Question 2

_________ is required if cells are to organize themselves and function properly as parts of multicellular organisms

Answer 2

communication

Question 3

one type of signal converted to another

Answer 3

signal transduction

Question 4

signaling requires cells to be in direct membrane-membrane contact

Answer 4

contact dependent

Question 5

depends on signals that are released into the extracellular space and act locally on the neighboring cells

Answer 5

paracrine signaling

Question 6

performed by neurons that transmit signals electrically along their axons and release neurotransmitters at synapses, which are located far away from the neuronal cell body

Answer 6

synaptic signaling

Question 7

depends on endocrine cells, which secrete hormones into the blood stream for distribution all over body.

Answer 7

Endocrine signaling

Question 8

work together to coordinate the activities of cells in widely separated parts of the body

Answer 8

endocrine cells and nerve cells

Question 9

Different cell types respond _________ to the same extracellular signal molecules

Answer 9

differently

Question 10

acetylcholine in salivary gland cells

Answer 10

causes secretion

Question 11

acetylcholine in heart muscle cell

Answer 11

decrease rate and force of contraction

Question 12

acetylcholine in skeletal muscle cell

Answer 12

cause contraction

Question 13

response time if it requires changes in already present proteins in the cell

Answer 13

very rapid

Question 14

response time if it involves gene expression and synthesis of new proteins

Answer 14

very slowly

Question 15

programmed cell death

Answer 15

apoptosis

Question 16

when deprived of all signals, cells activate a _________ program

Answer 16

suicide, called apoptosis

Question 17

cells are programmed to respond to _________ extracellular signals

Answer 17

multiple

Question 18

types of receptors signal molecules bind to

Answer 18

cell-surface receptors and intracellular receptors

Question 19

signals that cannot pass the membrane and bind to cell surface receptors

Answer 19

hydrophilic signal molecules

Question 20

signals that can pass through the membrane and bind to receptor proteins inside the cell

Answer 20

hydrophobic signal molecules

Question 21

cell surface receptors relay extracellular signals via _______

Answer 21

intracellular signaling pathways

Question 22

process of intracellular signaling pathways

Answer 22

1. receptor binds to extracellular signal
2. receptor activates intracellular signaling proteins
3. ISP’s activate effector proteins
4. effector proteins carry out specific cellular functions

Question 23

intracellular signaling proteins act as _________

Answer 23

molecular switches

Question 24

molecular switches in signal transduction are turned on or off by

Answer 24

addition or removal of phosphate groups

Question 25

____________ adds a PO4 group and turns on the molecular switch using _______

Answer 25

protein kinase, ATP

Question 26

___________ removes a PO4 group and turns off the molecular switch using _____

Answer 26

protein phosphatase, ATP

Question 27

GTP-binding signals switch on and off by

Answer 27

adding a PO4 group to GDP to make GTP, or removing a PO4 group from GTP to make GDP

Question 28

cell surface receptor fall into 3 main classes

Answer 28

ion-channel-coupled receptors, G-protein coupled receptors, enzyme-coupled receptors

Question 29

ion-channel-coupled receptors facts

Answer 29

1. typically multi pass transmembrane proteins 2. signal opens and closes ion channel 3. mediate rapid responses in nerve and muscle cells

Question 30

G-protein coupled receptor facts

Answer 30

1. receptor is typically a 7-pass transmembrane protein 2. receptor acts through a trimeric GTP-binding protein (G-protein) 3. G protein regulates activity of a separate plasma membrane-bound target enzyme or an ion channel

Question 31

enzyme-coupled receptor facts

Answer 31

1. single-pass transmembrane proteins 2. function either directly as enzymes or are directly associated with enzymes (e.g. kinases and phosphatases) that they activate

Question 32

largest class of cell-surface receptors (more than 700 in humans)

Answer 32

G-protein-coupled-receptors (GPCRs)

Question 33

almost half of all known drugs act through ______

Answer 33

GPCRs or G-protein-coupled-receptors

Question 34

hundreds of ________ are concerned with the sense of smell

Answer 34

GPCRs

Question 35

GPCR structure 1. single polypeptide chain passing in the cell membrane ______ times 2. receptor site faces _______ 3. G protein interaction site is on ________

Answer 35

1. 7 times 2. extracellular space 3. cytoplasmic side

Question 36

GPCR receptors act through a _______

Answer 36

trimeric GTP-binding protein (G-protein)

Question 37

trimeric G protein facts 1. A trimeric protein made of _____ 2. in the inactive form _____ is bound to GDP, in the active form this is replaced with GTP 3. ______ is bound to alpha and gamma subunits she in the inactive state 4. the alpha and gamma subunits are ______

Answer 37

1. alpha, beta, and gamma subunits 2. alpha subunit 3. beta subunit 4. attached to the plasma membrane through anchors (covalently attached lipid molecules)

Question 38

when activated, the alpha subunit of g-proteins carry

Answer 38

intrinsic GTPase activity, passing a phosphate group to other proteins to activate them.

Question 39

the activated alpha subunit of the G-protein can also activate membrane bound

Answer 39

enzymes

Question 40

cAMP levels are controlled by

Answer 40

1. adenylyl cyclase makes cAMP from ATP | 2. phosphodiesterase breaks down cAMP

Question 41

Cholera bacterium create cholera toxin, a protein that enters cells in the intestine and modifies the ______ to stimulate ________. The altered _________ is continuously active and keeps signaling to its target proteins.

Answer 41

alpha subunit of G-protein adnylyl cyclase alpha subunit

Question 42

cyclic-AMP regulates __________ which has an effect on _______ and __________

Answer 42

adrenaline skeletal muscle glycogen breakdown

Question 43

cAMP mediates adrenaline by activating

Answer 43

protein kinase A (PKA)

Question 44

cAMP activation of protein kinase A (PKA) can activate _________

Answer 44

gene transcription

Question 45

some G proteins regulate the activity of

Answer 45

phospholipase C

Question 46

GPCRs increase cytosolic Ca2 and activate _____

Answer 46

PKC

Question 47

GPCR signaling through phospholipase C Signal 1: ____ is water soluble and diffuses through the cytosol where it binds to ____ receptors on the ER. Ca2 is released into the cytoplasm. Signal 2: _____ remains imbedded in the membrane. _______ activates protein kinase C (PKC) along with Ca2. PKC then acts on a number of different substrates.

Answer 47

Signal 1: IP3 | Signal 2: diacylglycerol

Question 48

Among the enzyme-coupled cell-surface receptors, ___________ are particularly abundant in mammalian cells.

Answer 48

receptor tyrosine kinases (RTKs)

Question 49

_______ are key regulators of normal cellular processes and also have a critical role in the development and progression of many types of cancer.

Answer 49

Receptor tyrosine kinases (RTKs)

Question 50

enzyme coupled receptors facts

Answer 50

1. single-pass transmembrane protein | 2. cytosolic domain functions as an enzyme or is directly associated with enzymes

Question 51

Binding of signal molecules cause RTKs to ______. The RTKs _______ themselves and their interacting partner.

Answer 51

dimerize | phosphorylate

Question 52

Phosphorylated RTKs serve as __________ for other signaling proteins

Answer 52

docking sites

Question 53

Most RTKs activate the monomeric ________

Answer 53

GTPase Ras

Question 54

GTPase Ras facts

Answer 54

1. Ras is a small GTP binding protein that relays signal from RTKs 2. Ras contains covalently attached lipid molecules that anchor the protein to the cell membrane 3. Ras resembles the alpha subunit of GPCR and functions as a molecular switch in the same way

Question 55

30% of human tumors have activated forms of ____

Answer 55

Ras