Bartling Study Guide

Question 1

What do cellular signal transduction cascades do?

Answer 1

detect, amplify and integrate external signals

Question 2

What are cellular signal transduction cascades comprised of?

Answer 2

specific cell surface membrane receptors, effector signaling elements, regulatory proteins

Question 3

What are the 6 steps of signaling?

Answer 3

1. synthesis of a signaling molecule (ligand)
2. release of the signaling molecule (ligand)
3. Transport to signaling molecule to target cell
4. Binding of the ligand by a specific receptor protein and change in conformation
5. Change in cellular metabolism, function or development = cellular response
6. Removal of ligand, termination of cell response and degradation of ligand

Question 4

What are hormones?

Answer 4

Chemical messengers made by endocrine cells and secreted into the bloodstream.

Question 5

What do hormones affect?

Answer 5

gene expression and protein synthesis

Question 6

What hormone acts on the same cell that secreted them?

Answer 6

autocrine

Question 7

Which type of hormone acts on other cells?

Answer 7

paracrine

Question 8

What are types of hormones?

Answer 8

steroids, amine (AA derived and secreted from the thyroid and adrenal medulla), peptide, polypeptide

Question 9

What are some examples of cholesterol precursors of steroid hormones?

Answer 9

corticosteroids (cortisol), androgens (testosterone), estrogens

Question 10

Which type of hormones immediate diffuse out of endocrine cells into the bloodstream?

Answer 10

Steroid hormones

Question 11

Are steroid hormones lipid soluble?

Answer 11

Yes, can cross cell membrane

Question 12

Where are cytoplasmic receptors located for steroid hormones?

Answer 12

intracellularly, inside target cells

Question 13

Are steroid hormones for peptide hormones longer acting?

Answer 13

steroid hormones

Question 14

How do hormones lead to signal cascades?

Answer 14

1. hormones diffuse through phospholipid bilayer
2. Bind to receptor Turing on/off specific genes
3. mRNA directs synthesis of new protein
4. Proteins alters activity

Question 15

What are amine hormones derived from?

Answer 15

Tyrosine or tryptophan

Question 16

Where are amine hormones stored?

Answer 16

endocrine cells until secreted

Question 17

Where can the receptor for amine hormones be located?

Answer 17

cell surface or intracellular

Question 18

Which hormones do not immediately enter bloodstream?

Answer 18

polypeptide (can be stored in endocrine cell vesicles)

Question 19

Which hormones are water soluble?

Answer 19

polypeptide hormones, do not readily pass through cell membrane

Question 20

Why are polypeptide hormones termed first messengers?

Answer 20

bind to external receptors

Question 21

What mediates intracellular effects?

Answer 21

second messengers- low molecular weight signaling molecules (cAMP or calcium)

Question 22

What is the structure of G-protein coupled receptors?

Answer 22

integral membrane protein (extracellular N-terminus), 7 transmembrane spanning alpha helices, 3 extracellular and intracellular loops, Intracellular C-terminal tail membrane

Question 23

T/F G-protein coupled receptors have intrinsic catalytic domains

Answer 23

F

Question 24

What does G-protein activate?

Answer 24

adenylyl cyclase (converts ATP to cAMP) which activates protein kinases in the cytosol (signal cascade)

Question 25

What inactivates cAMP?

Answer 25

Phosphodiesterase

Question 26

What subunit contains the GTP-binding site and helps activate adenylyl cyclase?

Answer 26

Alpha subunit also contains intrinsic GTPase activity

Question 27

How many bound molecules of adenylyl cyclase can stimulate Gs alpha subunits?

Answer 27

one molecule can stimulate many Gs alpha subunits that amplify the original hormone signal

Question 28

What are some bacterial toxins that target G-proteins?

Answer 28

cholera toxin and Pertussis toxin (whooping cough)

Question 29

What occurs when cholera toxin is present?

Answer 29

increase in cAMP within intestinal epithelial cells leads to phosphorylation of Cl- channels and efflux of electrolytes and water (severe diarrhea)

Question 30

What happens when pertussis toxin is present?

Answer 30

enhances cAMP levels that inhibits neutrophil functions

Question 31

Do tyrosine kinase linked receptors have intrinsic enzymatic activity?

Answer 31

No

Question 32

What activates tyrosine kinases?

Answer 32

Ligand binding forms dimers activating tyrosine kinases that phosphorylate downstream targets (signal cascade)

Question 33

What are intrinsic enzymatic activity receptors?

Answer 33

ligand-triggered protein kinases, similar to tyrosine linked receptors (form dimers upon ligand binding)

Question 34

What does the ligand/receptor complex of intrinsic enzymatic activity receptors act as?

Answer 34

tyrosine kinase (phosphorylates other kinases) activating other protein kinases

Question 35

What happens when ligand binding to ion-channel receptors occurs?

Answer 35

confirmation change of receptor allowing specific ions (Na+, K+) to flow through

Question 36

What bacterial toxins indirecting affect ion channels?

Answer 36

botulinum toxin: prevents release of AcH NT and cleaves proteins involved in docking of NT vesicles

Question 37

What is the steep intracellular/extracellular calciumconcentration gradient of cells?

Answer 37

100nM/1mM enables radical changees in Ca concentration via hormone ligation

Question 38

What does calcium bind to inducing a formation change?

Answer 38

calmodulin, two globular domains joined by a long alpha helix

Question 39

What does the calcium/calmodulin complex bind to and modify?

Answer 39

target proteins (kinases) that initiate signal cascades

Question 40

What is the second messenger responsible for calcium mobilization?

Answer 40

phosphatidylinositol 4,5-bisphosphate (PIP2)

Question 41

What hydrolyzes PIP2?

Answer 41

PLC to generate two second messengers: inositol triphosphate (IP3) and diacylglycerol (DAG)

Question 42

T/F IP3 is water insoluble and can mobilize calcium

Answer 42

F; IP3 is water soluble and mobilizes calcium

Question 43

How is DAG anchored in the plasma membrane?

Answer 43

due to hydrophobic fatty acid side chains

Question 44

What can DAG activate?

Answer 44

key protein kinase C family

Question 45

What can phosphatylcholine produce when hydrolyzed by other phospholipase?

Answer 45

lipid second messengers: DAG species generated by PLC, Phosphatidic acid generated by PLD and arachidonic acid generated by PLA2

Question 46

What are key inflammatory and pain mediators?

Answer 46

arachidonic acid

Question 47

What are arachidonic acid precursors of?

Answer 47

eicosanoids: prostaglandins, prostacyclins, thromboxjnes, and leukotriene (all act like hormones and signal via G-protein coupled receptors

Question 48

What modulates smooth m contraction, platelet aggregation, gastric acid secretion and salt and water balance?

Answer 48

arachidonic acid

Question 49

What is involved in arachidonic acid conversion to prostaglandins?

Answer 49

cyclooxyrgenase isoforms | - COX-1 and COX-2 (made only in response to inflammatory mediators)

Question 50

What do prostaglandins do?

Answer 50

stimulate inflammation, regulate blood flow to organs such as the kidney, control ion transport across membranes, modulate synaptic transmission and induce sleep

Question 51

What inhibits cyclooxygenase?

Answer 51

non steroidal anti-inflammatory drugs (NSAIDs) - aspirin and Ibuprofen

Question 52

How do aspirin and ibuprofen inhibit cyclooxygenase?

Answer 52

block conversion to prostaglandins, aspirin irreversibly inactivates both forms

Question 53

What are effective treatments for inflammatory conditions? (rheumatoid arthritis)

Answer 53

inhibitors of COX-2

Question 54

What is arachidonic acid converted into leukotrienes by?

Answer 54

lipoxygenase

Question 55

How does receptor-independent signaling work?

Answer 55

low molecular weight signaling molecules (NO) cross plasma membrane and directly modulate activity of catalytic domains of transmembrane receptors or cytoplasmic signal transfusing enzymes

Question 56

What stimulate guanylate cyclase which generates cGMP (relaxes blood vessels)?

Answer 56

NO, angina symptoms treated with glyceryl trinitrate which is converted to NO

Question 57

Does endocytosis require ATP?

Answer 57

YES

Question 58

What is pinocytosis?

Answer 58

"drinking", nonspecific absorption of ECF

Question 59

Phagocytosis

Answer 59

"eating" activated any attachment of PAMPS

Question 60

Receptor-mediated endocytosis

Answer 60

selective, form vesicles containing receptors at surface of membrane (clathrin coated vesicles form polyhedral lattice)

Question 61

Movement of receptors to different membrane from the one in which it was endocytosed

Answer 61

transcytosis