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Biology 1510 > Chapter 9 > Flashcards

Chapter 9 Flashcards

1
Q

G protein

A

transmembrane protein that consists of 7 alpha helix that pass through the lipid bilayer 7 times

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2
Q

g protein subunits

A

alpha beta gamma

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3
Q

active vs inactive g protein

A 
inactive = gdp bound to alpha subunit
active= gtp bound to alpha subunit
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4
Q

describe the process that requires a GCPR receptor

A

the activation of the receptor is done by different neurotransmitters (synaptic signaling) that causes gcpr receptor to bind to g protein and exchange its gdp for gtp. The g protein then dissociates and gtp binds to the alpha subunit of and pulls away leaving behind the beta-gamma subunit.

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5
Q

what happens to gtp bound alpha subunit of g protein

A

it binds to an effector protein

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6
Q

Adenylyl Cyclase bound to gtp bound alpha subunit of g protein?

A

becomes enzymatically active and catalyzes the conversion of atp to CAMP, which binds to and activates PKA and then phosphorylates specific proteins leading to specific cellular responses (response proteins)

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7
Q

CAMP

A

CAMP is a second messenger signaling protein that originated inside the cell

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8
Q

PKA

A

protein kinase a

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9
Q

Response proteins of PKA

A

1) increased heart rate
2) breakdown of glycogen and glucose in skeletal muscles
3) breakdown of fats to fatty acids in fat cells

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10
Q

phospholipase c bound to gtp bound alpha subunit of g protein

A

activates and then cleaves (splits) PIP2 into IP3 and DAG (both act as 2nd messengers). IP3 opens CA2+ channel and releases Ca2+ and the binds to CA2+ binding proteins. where as DAG will signal the molecules of ATP

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11
Q

Ca2+ ion channel

A

because the lumen of smooth er has more Ca2+ than the cytoplasm and the Ca2+ ion channel is moving Ca2+ from the lumen to the cytoplasm and moving down the concentration gradient this is an example of passive transport

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12
Q

effects of phospholipase c

A

glycogen breakdown, amylase secretion, muscle contractions, aggregation

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13
Q

Vasopressin (protein hormone)

A

target tissue is in the liver and is responsible for glycogen breakdown

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14
Q

Acetylcholine (a)

A

target tissue is in the pancreas and secretes amylase which is a digestive enzyme

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15
Q

Acetylcholine (b)

A

target tissue is in the smooth muscle cells and causes contractions

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16
Q

Thrombin

A

target tissue is in blood platelets and causes aggregation which plays a very important role in blood clotting

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17
Q

diff receptors can produce the same 2nd messenger (ex?)

A

epinephrin and glucagon are two receptors that produce the same second messenger therefore producing similar results; they both stimulate the liver cells to breakdown glycogen to glucose-6-phosphate. they both bind to glucagon specific g protein receptors found in the plasma membrane of liver cells and completes the cycles of gcpr and adenylyl cyclase accordingly

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18
Q

what other receptors do liver cells have?

A

insulin (RTK) which lowers the blood glucose levels by converting glucose to glycogen therefore lowering the blood glucose levels.

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19
Q

define cellular communication

A

how cells attain signals from outside, how they respond to those signals and how they interact with each other

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20
Q

how do cells “talk”

A

the signaling cell produces a signal or a ligand and those ligans bind to the receptors of the target cells which responds to that signal

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21
Q

what can ligands be

A

they can be proteins, peptides, amino acids, steroids, fatty acid derivatives, or dissolved gasses.

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22
Q

what are the two different types of receptors

A

intracellular and membrane/cell surface

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23
Q

what is the intracellular receptor

A

it is found inside the cell usually in the cytoplasm or nucleus; they use hydrophobic ligands and simple diffusion to move across the plasma membrane; the ligands that usually bind to these receptors within the cells are steroids, gasses, and fatty acid derivatives

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24
Q

what is a membrane receptor

A

they are receptors that are embedded into the membrane they attach to hydrophilic ligands such as proteins, peptide bonds, or polar amino acids

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25
Q

what is the signal transduction pathway

A

converts the information in the signal into a cellular response

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26
Q

what are the different types of signaling

A

direct contact, paracrine, endocrine, synaptic, and autocrine

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27
Q

direct contact / contact dependent signaling

A

when a signal molecule on the plasma membrane of one cell contacts the receptor molecule on the adjacent cell
it is very important in early development
it uses gap junctions to allow exchange of ions, amino acids, and sugars

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28
Q

how is direct contact signaling important for early development

A

it allows cells that are initially similar to become specialized

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29
Q

how do gap junctions work in regards to direct contact signaling

A

they are gap channels made of proteins connexions that bond together between the plasma membrane of one cell to the adjacent membrane of another allowing for an exchange

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30
Q

what kind of receptor does direct contact signaling have

A

membrane bound receptors

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31
Q

paracrine signaling

A

is when the signaling cell releases short lived ligands that affect nearby target cells

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32
Q

what are short lived ligands

A

an example are usually growth factors or proteins that stimulate cell growth and division

33
Q

give an example of paracrine signaling

A

for example when we get a paper cut, growth factors bind to receptors which will lead to the duplication of cells therefore causing the cut to heal

34
Q

endocrine signaling

A

the signaling cell releases long lived ligands that travel through the circulatory system to induce several distant target cells; both animals and plants use this mechanism extensively

35
Q

what are the long lived ligands in endocrine signaling

A

hormones; they’re found in the endocrine glands

36
Q

what are the endocrine glands

A

they are made of endocrine cells that release hormones into the blood to get distributed

37
Q

give an example of endocrine signaling

A

when the levels of glucose in our blood increase, the beta cells of the pancreas release insulin hormones are released into the blood where they bind to the target distant cells which have insulin receptors located on fat, liver, and skeletal muscle cells which then convert excess glucose and glycogen in the skeletal muscle cells and liver cells but convert excess glucose to fats in fat cells

38
Q

synaptic signaling

A

occurs when the nerve cells release short lived ligands (neurotransmitters) into the gap (synapse, which forms between the nerve and its target cell

39
Q

what forms between the nerve and target cell

A

a synaptic guy

40
Q

what can the target cell be in synaptic signaling

A

another nerve cell, muscle gland, or endothelial cells

41
Q

what are endothelial cells

A

they line blood vessles: capillaries, arteries,

42
Q

besides being a short lived ligand, what are neurotransmitters

A

they are chemical signals released by the nerve cell into the synaptic gap

43
Q

autocrine signaling

A

when the cell sends a signal to itself; when the released ligand binds to the receptors of the same signaling cell the released the ligand

44
Q

give an example of autocrine signaling

A

in the presence of pathogens t cells produce ligands (growth factors) that bind the tcell receptors that produce them causing a divide meaning that they can provide a better immunity defense response

45
Q

what are the two types of intracellular receptors

A

steroid receptor or no receptor

46
Q

what type of steroid hormones could there be

A

testosterone, cortisol, estrogen

47
Q

what is cortisol

A

it is a hormone that is found in the adrenal glands on top of the kidney

48
Q

what happens after the steroid ligand is release

A

it binds to the steroid-hormone receptor; the ligands released to bind are hydrophobic ligands (they use facilitated diffusion/simple diffusion to move across the membrane)

49
Q

what does hormone binding do to the inhibitor

A

it alters the receptor conformation so it no longer binds to the inhibitor

50
Q

what is the inhibitors preventing before the hormone binds to the receptor

A

it is blocking the DNA binding site for transcription which will therefore prevent translation; because it affects transcription it also affects gene expression and prevents any of these three processes to happen

51
Q

what happens after the inhibitor is unable to bind to the DNA binding site due to the hormone ligand binding to the receptor

A

the hormone receptor complex translocates to the nucleus

52
Q

what occurs after the complex translocates to the nucleus

A

the hormone receptor complex binds to the DNA which usually turns on transcriptions (but also has the ability to turn it off)

53
Q

what is the overall cellular response to the signaling that occurs after the steroid hormone ligand binds to the receptor

A

the overall response is a change in gene expression

54
Q

what is an example of a type of signaling that requires no receptor. If able to name one, what does it require instead

A

one type of signaling is known as nitric oxide signaling and instead of a receptor it uses guanylyl cyclase

55
Q

what is the primary function of nitric oxide signaling

A

to provide assistance for vasodialation

56
Q

what is the purpose of vasodialation

A

provides an increase of blood flow into the body to tissues that need it the most

57
Q

what produces nitric oxide

A

it is produced by the lining of the the blood vessels known as the endothelial cells

58
Q

how does nitric oxide signaling work

A

first a nerve cell releases a short lived ligand usually a neurotransmitter which then binds to the receptor of its target cell, in this case endothelial cells, where the signal sent will convert L-arginine into Nitric Oxide which then rapidly diffuses across the membrane (paracrine signaling) through simple diffusion because the ligand is hydrophobic therefore activating the intracellular receptor. After rapid diffusion it does not bind to a receptor instead it binds to guanylyl cyclase which converts gtp to cyclic guanosine monophosphate (cGMP) therefore leading to vasodilation relaxing the smooth muscle cells

59
Q

what is viagra used to treat

A

it is used to treat erectile disfunction in men

60
Q

what are the two functions of guanylyl cyclase

A

guanylyl cyclase is made to be enzyme and can act as a receptor

61
Q

what can happen sometimes that causes erectile disfunction

A

erectile disfunction occurs after the conversion of GTP to cGMP when the enzyme phosphodiesterase catalyzes the conversion of cGMP to GMP which stops blood flow (vasoconstriction)

62
Q

what does viagra do that helps to stop erectile disfunction

A

it acts as an inhibitor to the enzyme phosphodiesterase to stop the conversion of cGMP to GMP

63
Q

what are membrane (cell surface) receptors

A

they are the majority of our receptors that are not inside our cells but rather they are embedded into the membrane

64
Q

what are the three membrane receptors

A

chemically gated ion channels, enzyme coupled receptors, G protein coupled receptors

65
Q

what happens in a chemically gated ion channel

A

the specific ligand which is usually a neurotransmitter binds to the receptor and then acts like an ion channel allowing the passage of of specific ions such as Na+, K+, Ca2+, or Cl-

66
Q

why doesnt the ligand cross the membrane

A

because it is hydrophilic

67
Q

what are examples of chemically gated ion channels

A

the acetyl choline receptor binds the neurotransmitter acetyl choline to itself in the plasma membrane of skeletal muscle cells which then allows only Na+ ions to pump because it behaves like a sodium ion channel

68
Q

what is acetyl choline

A

it is the most common neurotransmitter in the body produced by nerve cells)

69
Q

what are enzyme couples receptors

A

they are receptors that act like enzymes or associate themselves with enzymes found inside our cells and they are activated by ligands

70
Q

what are the most common enzyme coupled receptors

A

almost all of them are protein kinases which phosphorylate themselves or other proteins

71
Q

what is the most common enzyme coupled receptor

A

tyrosine kinases

72
Q

what is the overall purpose of tyrosine kinases receptors

A

they influence the cell cycle, cell migration, cell metabolism, and cell proliferation

73
Q

what are the parts of the receptors tyrosine kinases

A

the extracellular ligand binding domain - where the hormone / growth factor ligand binds
the intracellular kinase domain - made of many tyrosine amino acids and a single alpha helix

74
Q

what happens after the ligands bind to the tyrosine kinase receptors

A

they two receptors come together to form a dimer which then attach inorganic phosphates to the tyrosine from 8 atp molecules and response proteins bind to the phosphate groups which phosphorylates proteins

75
Q

why does dimerization occur

A

to activate kinases to transfer phosphate groups from atp attaches to tyrosine

76
Q

what are specific examples of RTKS

A

insulin receptors

77
Q

what is the purpose of insulin receptors

A

insulin will bind to extracellular domain to phosphorylate insulin response proteins to activate glycogen synthase to convert glucose into glycogen and lower blood glucose levels

78
Q

what is the enzyme phosphatases

A

enzymes that dephosphorylate different phosphorylated proteins

79
Q

what are kinase cascades

A

they are kinases that amplify a signal because a few signal molecules elicit a large cellular response

Biology 1510 (13 decks)

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