Cell-Cell Communication - Exam 3

Question 1

definition of a ligand

Answer 1

signaling molecule

Question 2

permeable ligand characteristics

Answer 2

small, hydrophobic, lipophilic

Question 3

example of permeable ligand

Answer 3

NO (vasodilation)

Question 4

impermeable ligand characteristics

Answer 4

H2O soluble, polar, charged

Question 5

example of impermeable ligand

Answer 5

growth factors/hormones like insulin

Question 6

definition of a receptor

Answer 6

target cell, shape altered, specific

Question 7

internal receptor characteristics

Answer 7

intracellular/cytoplasmic, hydrophobic ligands, binds to chromosomal DNA, gene expression

Question 8

cell surface receptor characteristics

Answer 8

transmembrane, hydrophobic membrane spanning region, intracellular domain inside cell, signal transduction

Question 9

examples of neurotransmitters

Answer 9

oxytocin, endorphin, dopamine, glutamate, glycine

Question 10

examples of signal molecules in cell physiology

Answer 10

estradiol, thyroid hormones, testosterone, vitamin D3, retinoic acid, neurotransmitters, light- phototransduction, pressure- mechanotransduction, NO, CO, eicosanoids, growth factors/hormones like insulin

Question 11

cell-cell signaling: gap junctions

Answer 11

passage of small molecules and ions like calcium

Question 12

cell-cell signaling: tight junctions

Answer 12

seal neighboring epithelial cells i.e. lung

Question 13

cell-cell signaling: adherens junctions

Answer 13

strong mechanical attachments i.e. cardiac muscle

Question 14

cell-cell signaling: desmosomes

Answer 14

link intermediate filament cytoskeleton i.e. skin

Question 15

cell itself signaling

Answer 15

autocrine- pain & inflammation

Question 16

adjacent/nearby cell signaling

Answer 16

paracrine, synaptic signaling

Question 17

distant cell signaling

Answer 17

endocrine

Question 18

prostaglandins

Answer 18

paracrine & autocrine in nature, produced at man different sites in the body

Question 19

ion-channel cell surface receptors

Answer 19

ligand-gated, transmembrane, Na, Ca, Mg, K, H, can pass through, nerve-muscle junction, neurons, glutamate & acetylcholine (cardiac/muscle cells, pancreatic acinar cells/exocytosis secretory granules)

Question 20

intrinsic enzymatic activity cell surface receptors

Answer 20

convert GMP into cGTP, atrial naturetic protein

Question 21

tyrosine kinase-linked cell surface receptors

Answer 21

cytokines, interferons, human growth factor

Question 22

G protein cell surface receptors

Answer 22

second messenger, causes change in membrane potential, epinephrine, serotonin, angiotensin II, glucagon

Question 23

examples of G protein cell surface receptors

Answer 23

rhodopsin, beta-adrenergic, frizzled

Question 24

short term cell responses

Answer 24

ligand gated ion channels (ms) & GPCR (min)

Question 25

long term cell responses

Answer 25

kinase linked receptors (hrs) & nuclear receptors (mins)

Question 26

ionotropic membrane receptors

Answer 26

transmembrane: trigger short term and rapid responses & postsynaptic effects, cations & H2O can move through

Question 27

ionotropic glutamate receptors

Answer 27

neuron burst/firing, NMDA (internal binding site for Mg2+)

Question 28

metabotropic membrane receptors

Answer 28

linked to G proteins, activates a second messenger, longer response, glutamate receptors

Question 29

examples of second messengers

Answer 29

cAMP, derivative of ATP, cGMP (visual reception in vertebrate eye) via rhodopsin, phospholipids, Ca2+, IP3, DAG

Question 30

IP3 signaling

Answer 30

ADH, TRH, TSH, Angiotensin II, release of Ca2+ from intracellular stores by activating protein kinase C

Question 31

PIP2 hydrolysis produces

Answer 31

DAG, IP3, PIP3 via phospholipase C, downstream of GPCR & receptor tyrosine kinase

Question 32

cAMP signaling

Answer 32

synthesized by ATP via adenylyl cyclase; ACTH, TSH, LH, FSH, PTH, Calcitonin, glucagon, hCG, odorants, epinephrine, CREB

Question 33

cAMP signaling activated by

Answer 33

PKA- activating/inhibiting protein activity, activating gene expression through transcription factors

Question 34

intracellular receptors

Answer 34

phosphorylase kinase activates glycogen phosphorylase catalyzes breakdown of glycogen to glucose-1-phosphate

Question 35

glycogen synthase

Answer 35

catalyzes glycogen synthesis

Question 36

elevation of cAMP & activation of protein kinase A

Answer 36

blocks glycogen synthesis & stimulates glycogen breakdown

Question 37

receptor inactivation done by

Answer 37

ligand degradation, endocytosis mediated receptor recycling, degradation of receptors by proteasomes, ligand sequestration by lysosomes

Question 38

Ca2+ as a signaling molecule

Answer 38

signal transduction via activation of ion channels and indirect signal transduction pathways like G protein coupled receptors and ryanodine receptors

Question 39

Calmodulin activated by Ca2+ binding

Answer 39

actin and myosin contraction

Question 40

Ca2+ intracellular concentration =

Answer 40

lower than typical extracellular concentration, actively pumped from the cytosol to the extracellular space, ER, and mitochondria

Question 41

Ca2+ signaling occurs when

Answer 41

cell stimulated to release Ca2+ from intracellular stores

Question 42

Ca2+ homeostasis maintained by

Answer 42

calcium permeable channels, transporters, and ATPases

Question 43

Ca2+ regulates what 3 things

Answer 43

(a)sexual development, circadian clock, protein folding

Question 44

in electrically non-excitable cells like RBC,

Answer 44

influx of Ca2+ regulates exocytosis, enzyme control, gene regulation, cell growth, proliferation, apoptosis

Question 45

depletion of Ca2+ from ER....

Answer 45

leads to Ca2+ entry from outside the cell by activation of SOCs, current created (CRAC), Orai1 & STIM1 activated (t lymphocytes)

Question 46

Ca2+ physiologic functions

Answer 46

depolarization of the heart, antigen stimulation of immune cells, muscle contraction, cellular motility, fertilization, learning and memory, activation of isocitrate dehydrogenase

Question 47

receptor mediated endocytosis

Answer 47

portion of plasma membrane invaginated, coated with clathrin, pinched off, forms an endosome

Question 48

LDL receptors recycled

Answer 48

arrestin: receptor desensitization degradation recycling generate signalosomes which scaffold proteins to make downstream signaling events