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MCM > Receptors and cell signalling > Flashcards

Receptors and cell signalling Flashcards

1
Q

Describe endocrine signalling

A

long distance signalling;
diffuse through blood;
long-lasting (takes minutes to reach target cell sometimes)

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2
Q

Paracrine signalling

A

acts locally upon (short lived) e.g. neurotransmitters

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3
Q

Autocrine signalling

A

all cells with receptor (including itself) respond to the ligand (growth factors of cancer cells)

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4
Q

juxtacrine/direct

A

to attached cell

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5
Q

acetylcholine effects on heart, skeletal muscle, and salivary gland:

A

heart cells relax, skeletal muscles contract, salivary gland secrete saliva

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6
Q

Describe a Guanine exchange factor

A

receptors on GCPR change a GDP for a GTP on G proteins

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7
Q

What is PLC? What is it’s function?

A

phospholipase C cleaves PIP2 into IP3 and DAG

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8
Q

What does Gs protein do?

A

cAMP pathway

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9
Q

How does the Cholera toxin modify the G protein

A

I keeps Ga in the GTP active form indefinitely by adding a ribose (to G protein);
Cl secretion is constantly turned on

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10
Q

another term for turning up a signal

A

potentiate

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11
Q

another term for turning down a signal

A

attenuate

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12
Q

another term for turning down a signal

A

attenuate

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13
Q

What desensitizes a signal?

A

hormone levels drop;
phosphodiesterases remove cAMP;
receptors are sequestrated (endosome) and destroyed (endosome to lysosome via proteases);
GRK (GCPR kinase) phosphorylate the receptor so that arrestin can bind to it

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14
Q

What are the different G proteins and what does each do?

A

Gaq-PLC, DAG, Ca, PKC
Gai-cAMP inhibition
Gas-cAMP
Ga12-RhoGEFs

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15
Q

What receptor is associated with epinephrine?

A

beta andren…ic

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16
Q

What receptor is associated with histamine?

A

histamine receptor

17
Q

What receptor is associated with epinephrine and norepinephrine?

A

alpha andrenergic receptor

18
Q

What receptor is associated with dopamine?

A

Dopamine receptor

19
Q

What receptor is associated with light?

A

Rhodopsin

20
Q

What is a calcium mediated pathway?

A

Gqa GCPR

21
Q

Describe the Gqa pathway cascade

A

ligand binds, GDP->GTP, G with GTP activates PLC, PLC separates PIP2 into DAG and IP3, IP3 binds to Ca channel on ER/SR,
Ca and DAG activate PKC, Ca forms calmodulin complex

22
Q

What is needed to activate PKC?

A

DAG and Ca

23
Q

What makes an acceptable nuclear hormone signal molecule?

A

hydrophobic molecules are best (steroid hormones), NO, growth factors

24
Q

How does an intracellular receptor work?

A

There is a DNA binding domain on a receptor, once ligand binds then an inhibitory protein is released from the receptor and acts like a transcription factor

25
Q

What are some hydrophobic ligands that are nuclear hormone signals?

A

cortisol, estradol, testosterone, vitamin D3, thyroxine, and retinoic acid

26
Q

If a CpG island is hypermethalated then what is occuring?

A

promoter region is inaccessible, DNA transcription does not occur

27
Q

How does hypermethylation of miRNA coding regions of DNA result in cancer?

A

miRNA binds complementary to mRNA to silence genes. If this is not occuring then bad RNA cannot be silenced through that mechanism

28
Q

If the epigenetic is Highly altered what might that indicate?

A

cancers have their own specific epigenetic patterns, as well as histone modifications

29
Q

If the CpG islands have a lot of methylation on their histones then what does that indicate?

A

There is likely transcription of this area

30
Q

What is an easier modification: to methylate histone or DNA?

A

histone

31
Q

What are the two hits that have to occur in order to get cancer?

A

DNA repair pathways must be mutated

Oncogenes must be expressed

32
Q

place in order of lowest to highest penetrance? Transposon, cell signalling, or DNA repair gene mutations?

A

Transposon lowest
cell signalling
DNA repair highest

33
Q

What are some mitogen pathway proteins? What do they do?

A

src, erb, and ras

If up-regulated they promote cell proliferation

34
Q

What are Growth inhibitor pathway proteins?

A

rb and apc

MCM (10 decks)

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