Exam 3 Phase 2 Flashcards

(58 cards)

1
Q

What is signal transduction?

A

Reception of an environmental stimulus by a cell, which leads to metabolic changes that adapt the cell to the stimulus

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2
Q

What are types of signal transductions?

A

Any information coming from outside. It can be temperature, light, anything. Not necessarily chemical

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3
Q

What are the 4 classes of agents in signal transduction?

A

Hormones, growth factors, neurotransmitters, and pheromones

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4
Q

What is a characteristic of growth factors?

A

Action is long lasting

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5
Q

How do the 4 classes of agents in signal transduction act?

A

All act through receptors

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6
Q

What is a characteristic of neurotransmitters?

A

Secretion close to target cells

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7
Q

What is a characteristic of pheromones?

A

Act upon cells in a different organism

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8
Q

What are hormones secreted by and how do they travel?

A

Secreted by endocrine glands, which travel through the bloodstream and bind to specific receptors on or in target cells

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9
Q

What is epinephrine?

A

Hormone and neurotransmitter that relies on electrical impulses

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10
Q

What is epinephrine secreted by?

A

Secreted from the adrenal gland, which promotes metabolic energy generation in muscles

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11
Q

What is glucagon secreted by?

A

Secreted by the pancreas, which acts upon the liver to promote gluconeogenesis

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12
Q

What is insulin secreted by?

A

Secreted by the pancreas, which promotes uptake of glucose into the cell

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13
Q

What does insulin promote in the long term?

A

Promotes gene transformation

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14
Q

What do hormones include, chemically?

A

Peptides or polypeptides
Steroids
Amino acid derivatives

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15
Q

Why is cholesterol important?

A

Because it is the compound we use to make all steroids

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16
Q

Where is cholesterol present and what is the main storage site for it?

A

It is present in every cell membrane because the body makes it and the cell membrane is the main storage site for it

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17
Q

What are examples of hormones that are peptides or polypeptides?

A

Insulin and glucagon

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18
Q

What are examples of hormones that are steroids?

A

Glucocorticoids and sex hormones

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19
Q

What are minerocorticoids?

A

Has minerals like Mg

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20
Q

How do steroids travel across a cell membrane?

A

They travel freely across the cell membrane because they are non polar

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21
Q

What are examples of hormones that are amino acid derivatives?

A

Catecholamines, such as epinephrine, and thyroxine (derived from tyrosine)

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22
Q

Where are hormone receptors located?

A

May be located in the plasma membrane or within the cell (nuclear receptors)

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23
Q

What is the structure of catecholamine?

A

H2N-CH2-CH2-phenyl with OH on C3 and C4

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24
Q

What are the 3 major classes of membrane bound receptors?

A

Proteins that influence second messenger synthesis
Ion channels
Proteins with intrinsic enzyme activity

25
Example of how acetyl choline is an ion channel?
Acetylcholine works in the neuromuscular junction. Binds to site in ion channel which opens it so ions can pass. Cholinesterase hydrolyzes acetylcholine so that the ion channel can close.
26
Hormone control is ________
Hierarchical
27
What is the fast track of sensory inputs from the environment?
Central nervous system --> Adrenal medulla --> epinephrine --> muscle, heart, adipose tissue
28
What is the long term, slow process track for sensory inputs from the environment?
Hypothalmus ___> hypothalamic releasing factors including glucagon and insulin goes to anterior pituitary ____> Pituitary hormones such as somatotropin makes either pancreatic beta cells or pancreatic alpha cells. Beta cells secrete insulin which goes to liver, muscle, and adipose tissue. Alpha cells secrete glucagon which goes to liver and adipose tissue
29
What does the Kd of hormones determine?
Lower Kd acts faster
30
What is an agonist?
Binds in place of the hormone and produces same reaction
31
What is an antagonist?
Binds in place of hormone and prevents binding of the actual hormone which prevents effect
32
Describe G protein coupled receptor
External ligand binds to receptor, activates an intracellular GTP binding protein which regulates an enzyme that generates an intracellular second messenger
33
Describe receptor tyrosine kinase
Ligand binding activates tyrosine kinase activity by autophosphorylation then kinase activates transcription, altering gene expression
34
Describe receptor guanylyl cyclase
Ligand binding to extracellular domain stimulates formation of second-messenger cyclic GMP
35
Describe gated ion channel
Opens or closes in response to concentration of signal ligand or membrane potential
36
Describe adhesion receptor
Binds molecules in extracellular matrix, changes conformation, thus altering its interaction with the cytoskeleton
37
Describe nuclear receptor
Hormone binding allows the receptor to regulate the expression of specific genes
38
What is the process of G protein coupled receptors?
1) Epinephrine binds to its specific receptor 2) Hormone receipt or complex causes the GDP bound to Galpha to be replaces by GTP, activating Galpha 3) Activated Galpha separates from the rest of the complex, moves to adenylyl cyclase, and activates it 4) Adenylyl cyclase catalyzes the formation of cAMP 5) cAMP activates PKA 6) Phosphorylation of cellular proteins by PKA causes the cellular response to epinephrine 7) cAMP is degraded, reversing the activation of PKA
39
What is the secondary messenger for epinephrine?
cAMP
40
What is a source of 2 second messengers?
Phosphatidylinositol 4,5-bisphosphate (PIP2)
41
What occurs in the phosphoinositide system?
G protein activates phospholipase C instead of adenylate cyclase
42
What does PIP2 separate into and how?
Phospholipase C cleaves PIP3 into IP3 and DAG
43
What does IP3 do?
Binds and opens calcium channels, releasing calcium from its intracellular stores in the ER
44
What does DAG do?
Protein kinase C is activated by DAG and calcium, which phosphorylates target proteins like calmodulin
45
What uses the phospholipase C pathway?
Acetylcholine
46
what do synaptic transmission events involve?
Involve the release of a chemical neurotransmitter
47
What is the neurotransmitter for cholinergic synapses?
Acetylcholine
48
what is the neurotransmitter for dopaminergic synapses?
Dopamine
49
What are the steps for the release of a chemical neurotransmitter?
1) Action potential in presynaptic terminal opens calcium channels 2) Calcium entry causes vesicle fusion and transmitter release 3) Transmitter molecules bind to excitatory receptors, receptor channels open, and sodium enters the postsynaptic cell
50
What is the nicotinic acetylcholine receptor?
A gated ion channel
51
How does the nicotinic acetylcholine receptor function?
It first undergoes an acetylcholine dependent conformational change, opening 5 subunit pore.
52
What happens to aacetylcholine in the synaptic cleft?
Acetylcholine is rapidly degraded in the synaptic cleft by acetylcholinesterase, restoring resting potential
53
What are the agonists and antagonists in the nicotinic acetylcholine receptor?
Nicotine is an agonist, tubocurarine is an antagonist (keeps channel open)
54
Which hormonal effects are short lived and which are long term?
Hormonal effects occurring through G-proteins are short lived, while those occurring through nuclear receptors involve longer term changes related to growth or cell differentiation
55
What do ligand bound nuclear receptors do?
Ligand-bound nuclear receptors act on DNA, and affect gene transcription
56
What do nuclear receptors do?
Nuclear receptors bind steroid and related hormones, which can diffuse through the plasma membrane
57
What do nuclear receptors possess?
Possess a zinc-containing N-terminal DNA binding domain and a C-terminal hormone-binding domain
58
Where do nuclear receptors bind?
Sites on the DNA called hormone response elements (HREs)