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Biochemistry > Test 3 - Bartling > Flashcards

Test 3 - Bartling Flashcards

1
Q

Cellular signal transduction cassettes detect, amplify, and integrate external signals comprised of:

A
  1. Specific cell surface membrane receptors
  2. Effector signaling elements
  3. Regulatory proteins
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2
Q

Six steps of signaling

A
  1. Synthesis of the signaling molecule (ligand)
  2. Release of the signaling molecule (ligand)
  3. Transport of 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, terminating cellular response
  7. Degradation of ligand
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3
Q

Define hormones

A

Chemical messengers made by endocrine cells and secreted into the blood

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4
Q

T/F: Hormones affect gene expression and protein synthesis

A

True

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5
Q

Autocrine hormones

A

Act on the same cell that they were secreted from

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6
Q

Paracrine hormones

A

Act on other cells

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7
Q

Types of hormones

A
  1. Steroids
  2. Amine (amino acid derived)
  3. Peptide (lumped with polypeptides)
  4. Polypeptides
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8
Q

3 Cholesterol Precursors:

A
  1. Corticosteroids
  2. Androgens
  3. Estrogens
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9
Q

What do steroids immediately do?

A

Diffuse out of endocrine cells into the blood

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10
Q

Are steroid hormones lipid soluble?

A

Yes. They can cross cell membranes.

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11
Q

Where are the steroid hormone receptors?

A

Intracellular (cytoplasmic) receptors are located inside target cells

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12
Q

Steroid hormones have a _____ (longer/slower) acting, _____ (longer/slower) half-life than peptide hormones.

A

Slower Acting

Longer half-life

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13
Q

How do steroid hormones lead to signal cascades?

A
  1. Hormone diffuses into cell
  2. Activated receptor hormone complex alters gene expression
  3. New mRNA directs synthesis of certain proteins to ribosomes
  4. New proteins alter cell activity
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14
Q

What are Amine hormones derived from?

A

Tryptophan and Tyrosine

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15
Q

Where are amine hormones stored until they’re secreted?

A

In endocrine cells

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16
Q

Where are amine hormone receptors located?

A

Can be located on the cell surface or intracellular

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17
Q

Do polypeptide hormones immediately enter the blood?

A

No. They can be stored in endocrine cell vesicles

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18
Q

Polypeptide hormones are ___ soluble

A

Water

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19
Q

Do polypeptide hormones readily pass through the cell membrane?

A

No

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20
Q

What are polypeptide hormones also called?

A

First messengers - they bind to external receptors

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21
Q

Intracellular effects are mediated by

A

Second messengers

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22
Q

Second messengers are ____ (low/high) weight signaling molecules such as:

A

Low molecular weight

Cyclic adenosine monophosphate (cAMP) or Calcium

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23
Q

G-protein coupled receptors are ___ ___ proteins

A

Integral membrane proteins (extracellular N-terminus)

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24
Q

G-protein coupled receptors have ___ (#) transmembrane-spanning alpha-helices (ligand binds to pocket)

A

7

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25
Q

G-protein coupled receptors have ___ (#) extracellular and intracellular loops.

A

3 - the third intracellular loop recruits G-proteins

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26
Q

G-protein coupled receptors have an intracellular ___-____ ____ ____

A

C-terminal tail membrane

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27
Q

Do G-protein coupled receptors have intrinsic catalytic domains?

A

No

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28
Q

G-protein (guanine nucleotide-binding) activates:

A

Adenylyl cyclases (converts ATP to cAMP). It also activates protein kinases in the cytosol (signal cascade)

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29
Q

Phosphodiesterase inactivates

A

cAMP (turns off cell response)

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30
Q

Specificity of a G-protein is conferred by the ___-____, which contains the GTP-binding site and an ___ ____ activity

A

Conferred by the alpha-subunit which contains the GTP-binding site and an intrinsic GTPase activity

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31
Q

Adenylyl cyclase is activated by:

A

The action of the alpha-subunit of the G-protein (Gs)

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32
Q

With adenylyl cyclase, each molecule of bound hormone can stimulate many Gs alpha-subunits that amplifies the:

A

Original hormone signal

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33
Q

2 Bacterial toxins that target G-proteins:

A
  1. Cholera toxin

2. Pertussis toxin (whooping cough)

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34
Q

With Cholera toxin, what does ADP do?

A

Ribosylates Gs alpha subunit

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35
Q

With Cholera toxin: An increase in ____ within the intestinal epithelial cells leads to _____ of Cl- channels and efflux of ___ and ___ (____ ____).

A

With Cholera toxin: An increase in cAMP within the intestinal epithelial cells leads to phosphorylation of Cl- channels and efflux of electrolytes and water (severe diarrhea).

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36
Q

With Pertussis toxin, what does ADP do?

A

Ribosylates Gs alpha subunit

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37
Q

With Pertussin toxin: The enhanced ____ levels inhibit ___ functions

A

Enhanced cAMP levels inhibit neutrophil

38
Q

Do Tyrosine kinase-linked receptors have intrinsic enzymatic activity?

39
Q

With Tyrosine kinase-linked receptors: Ligand binding forms a ____ that activates ___ ____ to phosphorylate downstream targets (signal cascade)

A

Ligand binding forms a dimer that activates tyrosine kinases

40
Q

Intrinsic enzymatic activity receptors are ____-triggered protein _____

A

Ligand-triggered protein kinases

41
Q

Intrinsic enzymatic activity receptors are similar to:

A

Tyrosine-linked receptors (form dimers upon ligand binding)

42
Q

With Intrinsic enzymatic activity receptors: Ligand/receptor complex directly acts as a ___ ___

A

Tyrosine kinase (phosphorylates other kinases)

43
Q

With Intrinsic enzymatic activity receptors: Phosphorylation activates _____

A

Other protein kinases

44
Q

In ion-channel receptors, ___ binding changes confirmation of the receptor

45
Q

Ligand binding in ion-channel receptors allows for:

A

Specific ions (sodium, potassium) to flow through the channel.

46
Q

___ ___ prevents the release of acetylcholine neurotransmitter and cleaves proteins involved in docking of neurotransmitter vesicles

A

Botulinum toxin

47
Q

Cells maintain steep intracellular (____)/extracellular (___) Calcium concentration gradient that enables rapid changes in Calcium concentration via __ ___

A

100nM

1mM

Hormone ligation

48
Q

Calcium binds to ___ protein, inducing conformational change

A

Calmodulin

49
Q

Calmodulin protein is __ __ __ joined by a long __ __

A

2 globular domains

long alpha helix

50
Q

Calcium/calmodulin complex binds to and modifies __ __ that initiate __ __

A

Target proteins (kinases)

Signal cascade

51
Q

________ is the second messenger responsible for calcium mobilization

A

Phosphatidylinositol 4,5-bisphosphate (PIP2)

52
Q

PIP2 is hydrolyzed by a __ __ __ __ (PLC) to generate 2 second messengers

A

PIP2 Specific Phospholipase C

53
Q

The 2 second messengers generates by hydrolyzed PIP2

A

Inositol triphosphate (IP3)

Diacylglycerol (DAG)

54
Q

IP3 is __ soluble and it mobilizes ___

A

Water

Calcium

55
Q

DAG is anchored in the plasma membrane due to:

A

Hydrophobic fatty acid side chains

56
Q

DAG activates:

A

Key protein kinase C (PKC) family

57
Q

_____ can be hydrolyzed to other phospholipases to produce other lipid second messengers

A

Phosphatidylcholine

58
Q

Second messengers produced by hydrolyzed Phosphatidylcholine

A
  1. Different species of DAG
  2. Phosphatidic acid
  3. Arachidonic acid
59
Q

Species of DAG are generated by

60
Q

Phosphatidic acid is generated by

61
Q

Arachidonic acid is generated by

62
Q

__ __ and __ are key inflammatory and pain mediators

A

Arachidonic acid and prostaglandins

63
Q

Arachidonic acid and prostaglandins are precursors of

A

Eicosanoids

64
Q

4 Eicosanoids

A
  1. Prostaglandins
  2. Prostacyclins
  3. Thromboxanes
  4. Leukotrienes
65
Q

Eicosanoids act like ___ and signal via:

A

Hormones

G-protein coupled receptors

66
Q

Arachidonic acid and prostaglandins modulate

A
  1. Smooth muscle contraction
  2. Platelet aggregation
  3. Gastric acid secretion
  4. Salt and water balance
67
Q

Arachidonic acid conversion to prostaglandins involves a ___ ___

A

Cyclooxygenase isoform

68
Q

2 cyclooxygenase isoforms

A

COX-1 (constitutive) and COX-2 (response to inflammatory mediators)

69
Q

COX-1 and COX-2 roles:

A
  1. Stimulate inflammation
  2. Regulate blood flow to organs such as the kidney
  3. Control ion transport across membranes
  4. Modulate synaptic transmission
  5. Induce sleep
70
Q

Example of cyclooxygenase inhibitors

A

Nonsteriodal anti-inflammatory drugs (NSAIDs)

Aspirin and Ibuprofen

71
Q

Role of cyclooxygenase inhibitors

A

Block cyclooxygenase conversion to prostaglandins

72
Q

___ irreversibly inactivates both forms

73
Q

Selective inhibitors of ___ are effective treatments for inflammatory conditions (rheumatoid arthritis)

74
Q

Arachidonic acid is also converted to leukotrienes by ___

A

Lipoxygenases

75
Q

Explain receptor-independent signaling

A

Low molecular weight signaling molecules that cross the plasma membrane and directly modulate the activity of the catalytic domains of transmembrane receptors or cytoplasmic signal transducing enzymes

76
Q

__ __ stimulates guanylate cyclase (generates cGMP (relaxes blood vessels))

A

Nitric oxide

77
Q

Angina symptoms treated with __ __, which is converted to __ __

A

Glyceryl Trinitrate

Nitric Oxide

78
Q

Explain endocytosis

A

Packaging of extracellular materials in vesicles at the cell surface

79
Q

Endocytosis requires __

80
Q

3 types of endocytosis

A
  1. Pinocytosis
  2. Phagocytosis
  3. Receptor-mediated endocytosis
81
Q

Pinocytosis is cell __

82
Q

Pinocytosis is the:

A

Nonspecific absorption of extracellular fluid

83
Q

Explain how pinocytosis works

A

Membrane caves in, then pinches off into the cytoplasm as pinocytotic vesicle

84
Q

Phagocytosis is cell __

85
Q

Phagocytosis is activated by attachment to:

A

Pathogen-associated molecular patterns (PAMPS)

86
Q

Receptor-mediated endocytosis is __

87
Q

Receptor-mediated endocytosis forms ___ at ___

A

Vesicles (containing receptors)

The surface of the membrane

88
Q

Receptor-mediated endocytosis has ___ coated vesicles (forms polyhedral lattice)

89
Q

An example of receptor-mediated endocytosis is

A

Iron transport via transferring receptor

90
Q

Transcytosis is the:

A

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

Biochemistry (6 decks)

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