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CHY1102 - Biological and medicinal chemistry > Signal transduction > Flashcards

Signal transduction Flashcards

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1
Q

what are the two main systems used by the body for signalling between cells?

A 
Hormones 
Electrochemical signalling (nerve signals)
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2
Q

What are the three main pathways of transducing extracellular signals to intracellular signals?

A

heterotrimetric G proteins
Receptor tyrosine kinases
Phosphoinositide cascade

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3
Q

Why is signalling important?

A

The different body parts need to co-ordinate their actions

The different cells in our body need to communicate

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4
Q

What are hormones classified into?

A

3 groups based on their action distance

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5
Q

What are the three main groupings of hormones?

A

Endocrine system
Paracrine system
Autocrine system

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6
Q

What is the endocrine system?

A

acts on cells distant from site of production and spread through the blood stream

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7
Q

What is the paracrine system?

A

Acts close to the site of production

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8
Q

What is the autocrine system?

A

Acts on the cell that produced the hormone

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9
Q

What is an example of the endocrine system?

A

Insulin

Epinephrine

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10
Q

What is an example of the paracrine system?

A

Interleukine-1 in the immune system

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11
Q

What is an example of the autocrine system?

A

Interleukine-2 in the immune system

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12
Q

What are the three functions of the endocrine system?

A

Maintains homeostasis
Responds to external stimuli
Follow various cycle

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13
Q

What does it mean by maintaining homeostasis?

A

The blood glucose level is strictly regulated by insulin and glucagon

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14
Q

What does it mean by responding to external stimuli?

A

Preparation for “fight or flight” using epinephrine and norepinephrine

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15
Q

What cycles does the endocrine system regulate?

A

Maturation

Menstrual cycle

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16
Q

What form are hormones often in?

A

Polypeptides, steroids or amino acid derivatives

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17
Q

Where do hormones go in the body?

A

They can travel all around the body because they are carried by the blood stream but they only interact with target cells

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18
Q

What do cells have?

A

Receptors specific to certain hormones

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19
Q

What cells respond to insulin and glucagon?

A

Muscle
Liver
Adipose

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20
Q

What do the muscles around blood vessels respond to? What do they do?

A

Respond to epinephrine

They increase or decrease blood flow when needed

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21
Q

What does the pancreas produce?

A

Insulin
Glucagon
Somatostatin

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22
Q

What does the pancreas contain?

A

Scattered clumps of cells called islets of Langerhans

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23
Q

What is insulin released by?

A

High blood glucose levels

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24
Q

What does insulin do?

A

Stimulate muscle, liver and adipose cells to absorb and store glucose

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25
Q

What is glucagon released by?

A

Low blood glucose level

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26
Q

What does glucagon do?

A

Stimulates liver and adipose cells to release glucose and fatty acids

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27
Q

What does somatostatin do?

A

Inhibit insulin and glucagon release

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28
Q

Why is the structure of thyroid considered strange?

A

Contains halogens

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29
Q

What two substances does the thyroid release?

A

Triiodothryonine (T3)

Thyroxine (T4)

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30
Q

What do T3 and T4 do?

A

Increase metabolism in most tissues

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31
Q

How are T3 and T4 transported and why?

A

Through the blood by carrier proteins because they are not water soluble so they are hard to transport in any other way

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32
Q

What type of carrier proteins are used for T3 and T4 transportation?

A

Thyroxine-binding globin

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33
Q

In the cells nucleus, what do T3 and T4 bind to?

A

Receptors that increase transcription rate of metabolic enzymes

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34
Q

What is the effect of iodine deficiency in T3 and T4?

A

Leads to goitre

Increased size of thyroid, causes swelling

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35
Q

What important biological processes is calcium important in?

A

Forms Ca5(PO4)3OH which is a mineral in the bone
Triggers muscle contraction
Transmits nerve signals

36
Q

What increases the concentration of Ca2+ in blood?

A

Parathyroid hormone and vitamin D

37
Q

What decreases the concentration of Ca2+ in blood?

A

Calcitonin

38
Q

What does calcitonin do?

A

Acts on receptors in bone and kidneys

39
Q

What does the adrenal gland release?

A

Epinephrine

Norepinephrine

40
Q

What does epinephrine and norepinephrine act on?

A

α- and β- adrenergic receptors

41
Q

What do β-adrenergic receptors do?

A

Stimulate glucose production in the liver and skeletal muscle
Stimulate lipid metabolism in adipose tissue
Relax smooth (involuntary) muscles in bronchi and blood vessels supplying skeletal muscles
Increase heart action

42
Q

What is the only structural difference between epinephrine and norepinephrine?

A

Methyl group

43
Q

What do α-adrenergic receptors do?

A

Stimulate contraction of blood vessels supplying peripheral organs (skin, kidneys)
Stimulate smooth muscles in lungs and gastro intestinal tract

44
Q

How many steroids does the body have?

A

More than 50 different types

45
Q

what are the three groups of steroids?

A

Glucocorticoids
Mineralocorticoids
Estrogens and androgens

46
Q

How are steroids transported?

A

In blood by binding to a transport protein, transcortin because they are water insoluble

47
Q

In general, what structure do steroids have?

A

4 ring structures

48
Q

What do glucocorticoids do?

A

They have nearly opposite effect of insulin

They affect carbohydrate, lipid and protein metabolism

49
Q

What do mineralocorticoids regulate?

A

Excretion of salt and water by the kidneys

50
Q

What do mineralocorticoids bind to?

A

Receptor in the cytosol

51
Q

Where do mineralocorticoids migrate to? What do they do there?

A

The nucleus and promote or repress transcription of metabolic genes

52
Q

What do androgens and estrogen’s affect?

A

sexual development and function

53
Q

What are oestrogen’s mainly produced by?

A

Ovaries

54
Q

What are androgens mainly produced by?

A

Testes

55
Q

What are androgens and oestrogen’s a type of?

A

Steroid

56
Q

What do progestines help to regulate?

A

The menstrual cycle and pregnancy

57
Q

What does the primary messenger do?

A

Binds to cell

58
Q

What does the secondary messenger do?

A

Relays the messages

59
Q

Where are external signals transduced?

A

Across the cell membrane, it is relayed to secondary messenger in the cell

60
Q

What are the three common secondary messengers?

A

Cyclic adenosine monophosphate (cAMP)
Tyrosine kinases
Phosphatidylinositide (PIP2)

61
Q

What are heterotrimetric G proteins?

A

A large group of receptors
Common signal transducers
>800 in humans

62
Q

What do heterotrimetric G proteins do?

A

They are a complex system that transmits and amplifies an extracellular signal

63
Q

What do heterotrimetric G proteins respond to?

A

Prostaglandins (pain + temperature control)

Hormones

64
Q

What do heterotrimetric G proteins control?

A

Smell
Taste
Vision

65
Q

What parts does the heterotrimeic G protein cascade have?

A 
Extracellular signal 
Receptor 
G protein
Adenylate cyclase (AC) 
inhibitor
66
Q

step 1 in heterotrimeic G protein cascade?

A

GDP is exchanged for GTP on binding to the receptor, requires signal substance to bind first.

67
Q

step 2 in heterotrimeic G protein cascade?

A

G protein binds to AC (adenyl cyclase) : cAMP is synthesised

68
Q

step 3 in heterotrimeic G protein cascade?

A

G protein slowly hydrolyses GTP to GDP

Spontaneous process

69
Q

step 4 in heterotrimeic G protein cascade?

A

inactivated G protein dissociates from A.C

70
Q

What tyrosine kinase signalling regulate?

A

Cell growth
Cell differentiation
Blood glucose levels (insulin)

71
Q

What is tyrosine kinase signalling?

A

Complex series of phsophorylations of proteins that promote or suppress gene expression

72
Q

Step 1 in tyrosine kinase signalling?

A

signal substance binds to the receptor tyrosine kinase (RTK)

73
Q

Step 2 in tyrosine kinase signalling?

A

RTK dimerises and autophosphorylates

74
Q

Step 3 in tyrosine kinase signalling?

A

an adaptor binds to RTK

75
Q

Step 4 in tyrosine kinase signalling?

A

There is now an inactive Ras (G-protein)

76
Q

Step 5 tyrosine kinase signalling?

A

Ras binds to the adaptor and the GDP is exchanged for GTP

77
Q

Step 6 tyrosine kinase signalling?

A

Activated Ras starts a phosphorylation chain - Raf -> MEK -> MAPK

78
Q

Step 7 in tyrosine kinase signalling?

A

MAPK enters nucleus and phosphorylate transcription factor

79
Q

What does the phosphoinositide cascade do?

A

Regulate intracellular Ca2+ levels

80
Q

What is PIP2 a part of?

A

The membrane
As a phosphorylated glycolipid.
It is a source of arachidonic acid

81
Q

What does Ca2+ activate?

A

Kinase regulate

82
Q

Step 1 of phosphoionositide cascade?

A

There is an exchange of GDP to GTP activates G protein

83
Q

Step 2 of phosphoionositide cascade?

A

Active G protein binds to phospholipase C (PLC)

84
Q

What is PLC?

A

G protein complex hydrolyses PIP2 to inositol triphosphate (IP3) and a diacylgycerol

85
Q

What is the secondary messenger in phosphoionositide cascade?

A

IP3

86
Q

What does IP3 activate?

A

IP3 gated Ca2+ channel

87
Q

What is the last step of phosphoionositide cascade?

A

Protein kinase C (PKC) phosphorylates various proteins

CHY1102 - Biological and medicinal chemistry (13 decks)

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