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Bio 121 > Exam#4 > Flashcards

Exam#4 Flashcards

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0
Q

T/F every molecular mechanism in every cell can be altered by signals to meet organism needs?

A

True

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1
Q

Why do multicellular organisms have complex intracellular communication systems?

A

To coordinate cellular fxn based on organism needs

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2
Q

What are the basic components of a signaling system between two cells?

A

1) ligand is sent from signal cell
2) receptor on the target cell
3) signal transduction pathway within the target cell
4) target mechanism in the target cell that the signal produces

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3
Q

What is the primary signaling molecule

A

It is the ligand sent from the cell of orgin (signal cell)

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4
Q

What is a second messenger cascade

A

(Signal Transduction Pathway) It is the intracellular series of signal transducing molecules within the receiving cell

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5
Q

What is a target mechanism

A

(Effector mechanism) molecular event in the receiving cell that the signal is meant to produce

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6
Q

Two ways for ligand to access the receptor

A

1) ligand secreted into fluids of the body

2) ligands transduce info through cellular contact

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7
Q

3 fluids ligands can be secreted into

A

1) blood(endocrine ligands)-can reach every cell
2) local fluids(pacacrine ligands)-only reach a few cell types w/in a tissue
3) neural synaspe(neurotransmitter)-reach a single cell

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8
Q

If ligand travels by blood

A

It is an endocrine ligand. It has the potential to reach every cell in the body

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9
Q

if ligand travels by local fluids

A

It is a pacacrine ligand. Can only reach a few cell types within a certain tissue

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10
Q

If ligand travels by Neural Synapse

A

It is a neurotransmitter. It can reach a single specific cell.

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11
Q

Endocrine ligand

A

travels by blood. can reach every cell in the body

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12
Q

Pacacrine ligand

A

travels by local body fluids, It can only reach a few cells within the tissue

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13
Q

Neurotransmitter

A

a signal that travels by neural synapse. It can only reach a single cell.

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14
Q

2 ways ligands can tranduce info through cellular contact

A

Through 1) soluble

or 2) immobilized ligands.

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15
Q

soluble ligands

A

closely related cells can communicate by directly sharing 2nd messenger molecules w/in their cytosols through gap jxns

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16
Q

Immobilized ligands

A

found on surface of cells or in ECM of tissues can bind to downstream cell receptors and fxn like soluble ligands.

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17
Q

A cells ability to respond to specific signals is regulated by

A

its phenotype.

the expression of certain receptors, signal transduction pathways, and target mechanisms

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18
Q

A cellular response to a signal or multiple signals is hard wired and can only be changed by

A

a change in phenotype. which receptor, signal transduction pathways, and target mechanisms it expresses.

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19
Q

2 major classes of receptor proteins

A

1) receptor proteins that reside in transmembrane position in the pm and respond to water soluble ligands
2) receptor proteins that reside inside of the cell and respond to ligands that pass the pm.

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20
Q

Receptor proteins that reside in a transmembrane position in the pm responds to

A

water soluble ligands

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21
Q

Receptor proteins that reside inside the cell responds to

A

ligands that pass the pm

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22
Q

Why are intracellular second messenger casacades so complex

A

so the cell can control them better and allow multiple signaling pathways to communicate w/in a cell

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23
Q

target mechanisms are hardwired to every single cascade and can be changed

A

with a change in phenotype

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24
G-protein linked receptor system
- common signal transduction system - uses a 7-pass transmembrane plasmamembrane receptor which is linked to a trimeric GTPase protein in the cytosol to transduce soluble external signals. - the membrane receptor is activated by a ligand which in turn activates its linked-Gprotein. - The activated Gprotein then can either activate the effector enzyme Adenyl Cyclase or Phosphoipase C.
25
Adenyl Cyclase
An effector enzyme that is activated by a G-protein GTPase in a G-protein linked receptor system
26
Phosphoipase C
An effector enzyme that is activated by a G-protein GPTase in a G-protein linked receptor system
27
Common signal transduction systems that utilize enzyme activation in the cytosol
1) Activation of Receptro Tyrosine Kinase->ras->MAP kinase cascade 2) Activation of Receptor Serince-Threonine Kinase->SMAD
28
Tyrosine Kinase System
- A common signal transduction system that utilizes enzyme activation in the cytosol to transduce soluble external signals. - The activation of Receptor: Tyrosine Kinase System leads to activation of ras (a monometric G-protein) which in turn activates the MAP Kinase cascade.
29
ras
a monometric G-protein which is activated by the Receptor Tyrosine Kinase. It activates the MAP kinase cascade
30
MAP kinase cascade
A target mechanism which is activated by ras in the receptor tyrosine kinase system
31
Serine-Threonine Kinase System
- a common signal transduction system expressed in cells that utilizes enzyme activation in the cytosol to transduce soluble external signals. - The activation of Receptor: Serine-Threonine Kinase leads to the activation of SMAD
32
SMAD
A target mechanism which is activated by the receptor serine-threonine kinase
33
Specialized signal transduction pathways
- have evolved in humans | - inhibitor inhibition pathways: Hedgehog, Wnt, thrombin-PPAR
34
inhibitior inhibition pathways
- A specialized signal transduction pathway that has evolved in humans - Hedgehog, Wnt, thrombin-PPAR
35
How do cells regulate the many signals they receive
They must integrate them based on hierarchy of importance and regulate their fxns based on multiple required signals
36
Ligand-Receptor Specialization
- A way to regulate signals - Ligand-receptor affinity and rate of turnover determine the sensitivity of the signaling system - gene expression hard-wires cells to respond to only certain signals.
37
Single target mechanism pathways
when a hardwired target mechanism is achieved in absence of a ligand (convergent crosstalk)
38
Convergent Cross-talk
(Redundant Cross-talk) occurs when TWO OR MORE ligands can produce the SAME target mechanism (used for essential responses!) -single target mechanism pathways
39
Divergent Cross talk
Used for complex, integrated responses where a SINGLE ligand can activate TWO or MORE systems -multiple target mechanism pathways
40
Actions from combinations of signals
neuron action potentials, cell division, and immune cell activation
41
Mechanisms from combination of signals
summation of ion movements at plasmamembrane, transcription factor expression in the nucleus and combined cytosolic and nuclear activation
42
Complex fxns vary by
the combinations of signals present
43
Signal pathway structure depends on
the desired fxn
44
Contractile regulation of skeletal muscle
- designed to produce voluntary, "all or nothing" contractions - great power - subject to fatigability
45
Contractile regulation of cardiac muscle
- designed to produce involuntary, "all or nothing" contractions - moderate power - not subject to fatigability
46
Contractile regulation of smooth muscle
- designed to produce involuntary, continuum contractions - low power - not subject to fatigability
47
BASIC components to all signals
1) ligand (biochemistry and mode of delivery) 2) receptor 3) second messenger cascade 4) target mechanism(s)
48
Ligand
the signaling molecule
49
Paracrine signaling system
local, short distance, intercellular | growth factors, cytokines, gasses, autocrine
50
autocine signaling
ligand secreted acts on the same cell type | -paracrine system
51
Endocrine signaling system
- systematic, long distance, interceller | - hormones released in the bloodstream (amphipathic ligands-cortisol, estradiol, testerone, vet d, acid, thyrome)
52
Synaptic signaling system
short distance like paracrine systematic like endocrine (glucose ions-dopamine, sertonin, endophin) -adaption for systematic regulation in anamalia
53
Systems that do not require a receptor
1) exchange of cytosolic components | 2) juxtacrine signaling
54
Which is not true about contractile regulation of skeletal muscle??
Involuntary activity
55
Which is not true about contractile regulation if cardiac muscle??
Activity is subject to fatigability
56
Nearly half of all drugs been developed act on which type of receptor?
G protein linked receptor
57
Upon entering the cell, lipid soluble hormones bind to a specific receptor present in the cytoplasm. The receptor hormone complex in turn,
Binds to DNA in the nucleas and acts as a transcription factor
58
A single Ligand activating its own novel pathway as well as affecting those of other ligands is an example of
Integration
59
How is the trimeric G protein activated?
Once a ligand binds to the receptor, the receptor undergoes conformational change and that leads to conformational change of the G protein; thereby allowing the removal of a GDP in exchange for a GTP molecule
60
What is the fxn of DAG in the G protein linked phospholidase c pathway??
Recruits protein kinase c (PKC) to the plasma membrane
61
Which is not true about contractile regulation of smooth muscle?
All or nothing contractions of low power
62
Which of the following statements best describes the process of desensitization?
A receptor is bound by a ligand, thereby activating the receptor. however, a protein binds to the cytosolic domain of the receptor, thereby preventing activation of the intracellular signaling pathway.
63
Phosphorylation CREB can bind to
A promoter, to regulate gens expression, in the nucleus
64
What is the sequence of events that occur during the regulation of cardiac muscle contraction?
Spontaneous action potential, dihydropuradine in t tubule membrane, influx of ca2+ from extracellular matrix
65
List 4 components of a signaling system in order of activity
Ligand, receptor, second messenger cascade, target mechanism
66
Which is an example of convergent cross talk?
Glycogen breakdown in the liver can be induced by both glucagon from the pancreas citing through CAMP and vasopressin from neural pituitary acting through PLC-Beta
67
Which activities that require ca2+ does not involve calmodulin?
Ca2+ mediated tropomysin movement to expose myosin binding site
68
What is not a fxn of the second messenger cascade?
Down regulation

Bio 121 (2 decks)

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