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Biology of disease > metals in disease > Flashcards

metals in disease Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

why must the concentration of each metal be just right?

A

can cause mismetal binding at site for other metals

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2
Q

examples of where iron is used in the body?

A

iron sulphur clusters, cytochromes, haemoglobin and mono/di nuclear ion sites

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3
Q

difference between cytochromes and haemoglobin?

A

cytochromes are used in electron transfer whereas haemoglobin is for gas binding. cytochromes also have 6 bonds where as haemoglobin has 5 to hold the gas.

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4
Q

what are the two states iron exists in the body ?

A

fe2 and fe3 - losses and electron to go form 3 to 2

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5
Q

examples of dinuclear ion sites

A

ribonuclotide reductase

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6
Q

example of mono ion site

A

iron oxygenases

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7
Q

where are iron sulphur clusters made?

A

in the mitochondria

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8
Q

where does the inorganic iron come from ?

A

cysteine

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9
Q

what does frataxin do ?

A

donates the iron to be used in isc

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10
Q

where is heme made?

A

in the mitochondria and cytosol

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11
Q

what does FECH stand for?

A

ferrochelatase

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12
Q

what does FECH do ?

A

catalysis of the final step in binding iron in heme

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13
Q

which metal binds with heme when iron is low?

A

zinc

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14
Q

what happens if there is too much iron?

A

mis metalation and drives dangerous reactions - fenton

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15
Q

what does SOD stand for?

A

superoxide dismutase

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16
Q

what does SOD do ?

A

catalysis of 202 +h2-> h2o2 +o2 , produces hydroxide which is safer than the superoxygen radical at the start.

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17
Q

what does the fenton reaction do ?

A

make very dangerous hydroxyl radicals
Fe2+ + h202-> Fe3+ +OH +OH-
OH is the hydroxyl radical - iron looses the e- and it goes to the OH- to make OH

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18
Q

where is iron stored in the body?

A

ferritin -24 subunits allows Fe2+

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19
Q

whats in the centre of the ferritin ?

A

feroxidase which oxidised the fe2 to fe3 and deposits it

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20
Q

how do you test of anaemia ?

A

test for ferritin in serum as single subunits not the 24 seen normally , also should be in cells not outside

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21
Q

how do cells get iron ?

A

have transferrin receptors on their surface which bind to diferric transferrin in the blood

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22
Q

what does IRP stand for?

A

Iron response protein

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23
Q

what binding site does it have?

A

for iron sulphur clusters

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24
Q

what happens when iron is low with IRP?

A

they are left unbound, can then bind to iron responce elements ( stem and loop on RNA). can bind at 5’ or 3’ .

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25
Q

what happens if IRP bind to IRE at 3’ ?

A

helps to stablises the message, stops degradation from nucleases therefore more transferrin receptor is made

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26
Q

what happens if IRP binds to IRE at 5’?

A

it blocks transcription of ferritin

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27
Q

how does the liver detect iron levels?

A

ratio between iron bound transferritin and non bound. liver then makes hepcidin when iron levels are high to block ferroporin being made which exports fe into the blood steam .

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28
Q

how is iron taken up in the digestive system ?

A

Dmt1 takes fe3+ into enterocytes then fe2 to ferroportin and into blood where its picked up by transferrin

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29
Q

what does hephasestin do?

A

converts fe2 to fe3 using its copper iron

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30
Q

what does Dmt1 do in endosomes?

A

pumps iron out of endosome which has the pathogen trapped to starve it or iron

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31
Q

what are the 3 theories for NRAMP1 ?

A

that its a super iron transporter to get rid of the final bits of iron in the pathogen
pumps iron into the endosome as a way of triggering the fenton reaction which would produced hydroxyl radicals to kill the pathogen
both Dmt1 and NRAMP1 pump iron out of the endosome, but you want the OH make by the bacteria not the endosome so h202 or superoxide diffuse into bacteria and tigger reaction .

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32
Q

how do bacteria scavenge iron and heme?

A

cause cells to lysis - blood

bacteria has a HASA binding site for heme and sends out HASR to bind to heme and allow up take

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33
Q

what are siderophores?

A

small molecules which bacteria send out to get iron

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34
Q

what do siderophores cause?

A

competition between bacteria - only they can collect iron bound to their own siderophores

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35
Q

how does as host respond to siderophores?

A

produces siderocalins

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36
Q

what are the two main uses for copper in the body ?

A

respiration - cytochrome c oxidase, anitoxidants - super oxidase dismutase

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37
Q

whats the transporter for copper into cells?

A

Ctr1

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38
Q

how does Ctr1 work?

A

It has a negative entrance, selectivity filter with cystine residues which regulate copper flow, central cavity which is positive to push coper through to the exit which is negative

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39
Q

whats the copper transporter into compartments or out of cells ?

A

ATP7A/B

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40
Q

how many heavy metal binding domains do humans have ?

A

6

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41
Q

what do heavy metal binding domains do ?

A

regulate copper

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42
Q

what does ATP7A/B need to work?

A

ATP conformational change

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43
Q

What happens when copper is low?

A

ATP7A is present on the Golgi body ER and allowing proteins being made to obtain the copper

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44
Q

what happens when copper is high ?

A

ATP7A is moved to the cell surface and pumps the excess cu out of the cell into the serum

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45
Q

how seems ot regualte this cycling of atp7a?

A

motifs

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46
Q

what is an enterocyte?

A

cells which line the intestine

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47
Q

what are hepatocytes ?

A

liver cells

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48
Q

what form of ATP7 do liver cells have?

A

ATP7B

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49
Q

what happens when copper is high in ATP7B cells ?

A

ATP7B moves to the bile canaliculus and pumps cu into the bile

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50
Q

what causes menkes disease

A

ATP7A mutations , only has one heavy metal domian

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51
Q

what is a symptom of menkes ?

A

kinky hair

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52
Q

what causes wilsons disease?

A

ATP7B mutations

53
Q

what happens in wilsons disease?

A

excess cu is not removed builds up in liver and causes liver damage

54
Q

what roles do ATP7A/B have in cu transport in the brain ?

A

ATP7A - cu into spinal cord B - out

55
Q

examples of some therapies used to treat wilsons and menkes ?

A

penicillimine - removes excess cu

copper histidine - bypass ATP7A/B

56
Q

what other metal can ATP7A/B and Ctr1 use?

A

platinum

57
Q

what does cisplatin do?

A

prevents proliferation of rapidly / cells - cancer treatment

58
Q

what mediates susceptibility/ resistance of cisplatin ?

A

Ctr1

59
Q

two current theories for how cu is transported in plasma?

A

ceruloplasmin - mutlicopper oxide which has 4 tightly bound cu atoms but can weakly atrract others
Albumin - has a weak attraction for cu but is very common in plasma

60
Q

How is too much cu toxic?

A

triggers the fenton reaction and mismetallation

61
Q

whats the irving williams series ?

A

the prescribed binding order of metals - cu very high

62
Q

if cu availability is kept very low, how does it get to where it needs to be ?

A

metallochaperones delivers cu to its locations

63
Q

whats CCS?

A

copper chaperone for SOD

64
Q

why are neurological disorders through to be linked to mis metallation ?

A

metals found in plaques

65
Q

what is cobalt a cofactor of?

A

b12

66
Q

what type of ring does b12 have?

A

corrin ring

67
Q

how do you get variations of b12 ?

A

different groups attached to the lower ligand

68
Q

how many states does cobalt have?

A

3- 1+,2+,3+

69
Q

what are the two enzymes that need b12?

A

methylmalohyl Coa mutase and methionine synthase

70
Q

what does methylmalonyl Coa mutase do

A

breaks down aa and produces a key molecule of TCA cycle

71
Q

what happens if methmalonyl coa mutase mutates ?

A

leads ot methylmalonic acidemia and neurological issues

72
Q

why is methionine synthase important?

A

produces methionine - starting amino acid of every protein

73
Q

what happens when methionine synthase mutates ?

A

build up of homocysteine which can lead to blindness

and megablastic anaemia - huge red blood cells

74
Q

why does megablastic anaemia occur?

A

cause methionine is key for red blood cell maturation

75
Q

which organisms made B12?

A

bacteria - only 30%

76
Q

where at the 2 places that cobalt can be introduced into b12 in bacterial pathways ?

A

early - anaerobic

late- aerobic

77
Q

what enzyme is used to insert cobalt into b12 in the early pathway?

A

cbiK - chelatases

78
Q

what is used to insert cobalt into b12 in the late pathway ?

A

cob W - chaperone

79
Q

how do humans get B12?

A

through meat and dairy - cows have bac in their guts which produce b12

80
Q

why do peas show symptoms of low cobalt ?

A

cause they have nitrogen fixing bac in their roots which need the cobalt to make b12

81
Q

what does a decrease in b12 during pregnancy cause?

A

spina bifita

82
Q

why do low b12 levels cause spinal defect ?

A

methionine synthase makes myelin for neurotransmitters
methylmalonyl Coa mutase reduced activity may cause an increase in methylmalonyl Coa which produces MMA (methylmalnic acid ) - destabilises myelin

83
Q

why is a b12 deficiency increase with old age ?

A

less intrinsic factor is produced, intrinsic factor binds closely with b12 and thus is taken up via cubulin from the intestines

84
Q

what happens if you have too much cobalt ?

A

neurotoxicity, pneumonia and lung cancer

85
Q

what is MOCO?

A

molybdenum cofactor

86
Q

what is MOCO needed for?

A

sulphite oxidase and xanthine oxidase

87
Q

what does sulphite oxidase do?

A

detoxifies sulphite

88
Q

what does xanthine oxidase do?

A

catabolism of purine

89
Q

what happens if MOCO mutates in humans ?

A

toxic metabolites build up causes death

90
Q

what is manganese needed for ?

A

mtSOD and glutamine syntheses

91
Q

what does glutamine synthese do ?

A

recycles glutamate in neurotransmitters

92
Q

what transports manganese ?

A

DMT1

93
Q

what happens when you have too much manganese ?

A

similar symptoms to Parkinsons

94
Q

what sequesters manganese in infections ?

A

calprotectin

95
Q

why is lime disease so hard to treat ?

A

evolved not to use iron therefore bodies defences dont work to kill it

96
Q

what percentage of all enzymes in the body need zinc?

A

9

97
Q

what is zinc mainly used for?

A

structural roles such as zinc finger motifs

98
Q

how did the prevalence of zinc change across evolution?

A

once the world became more aerobic , oxygen realesed zinc from zinc sulphur clusters by oxidation

99
Q

what does zinc bind to in the finger motif ?

A

cysteine and histodine

100
Q

why are zinc fingers useful?

A

they bring sections of the protein together creating a surface structure

101
Q

where is zinc normally transported in ?

A

into cytoplasm from serum or into cells from vesicles

102
Q

what transporter is associated with pumping zinc in?

A

ZIP

103
Q

what transporters pump zinc out of cells?

A

ZNT

104
Q

how is zinc levels within a cell regulated?

A

if zinc is too high zip transporter is endocytosed so no more zinc can be brought in, if too low then zip is made but cleaved to make it more efficient at zinc transport

105
Q

what is the transporter for dietary zinc?

A

ZIP4

106
Q

what causes acrodermatitus enteropathica ?

A

mutations in ZIP4 - treated with zinc supplements

107
Q

how is zinc moved about the body?

A

via albumin - weak association but lots of them

108
Q

how does albumin release the zinc?

A

needs fatty acids

109
Q

how does zinc work in insulin produciton?

A

forms zinc insulin crystals within vessicle which then get released and the crystal dissolved

110
Q

why might mutations in ZNT8 link to diabetes ?

A

ZNT is present at the beta cell surface in the pancreas and can be recognised as an antigen causing autoantibody production

111
Q

what happens to zn levels in prostate cancer?

A

they decrease

112
Q

what does aconitase have?

A

iron sulphur clusters

113
Q

why does aconitase need to be turned off in the prostate?

A

to allow citrate production and lower ph

114
Q

how is aconitase shut down?

A

via zinc

115
Q

where is zinc stored?

A

metallotheronein (mt) which has alot os cysteine residues which binds 4 and 3 zn

116
Q

what does MTF stand for?

A

metal transcription factor regulator

117
Q

what does MTF1 have?

A

a weaker affinity for zinc than normal zinc finger motifs but it means that zinc only binds to it when zinc levels are higher than normal

118
Q

when zinc is bound to MTF1 what happens?

A

MTF1 binds to the dna complex and interacts with MRE causing production of more metallothronein

119
Q

what does MRE stand for?

A

Metal responce elements

120
Q

how does cadmium also cause an increase in metallothronein ?

A

binds to MT causing zinc atoms ot be displaced leading them to bind to MTF1 increasing MT production

121
Q

what roles does zinc have at the synapse?

A

shuts off glutamate receptor by binding to them

122
Q

what is galvanising?

A

coating something in zinc

123
Q

what holds zinc from bacteria?

A

calprotectin

124
Q

what do bacteria produce to get host zinc ?

A

metallphore which competes with calprotectin

125
Q

issue with host withholding all zinc ?

A

some bacteria grow better with a lower concentration of zinc

126
Q

when does calprotectin actually start holding metals?

A

after it has been released from neutrophils and encounters high levels of calcium

127
Q

what does PsaA do?

A

is a surface protein which bacteria use to get manganese

128
Q

how does zinc interact with PsaA ?

A

binds to it , meaning the bacteria cant get manganese and are at risk of oxidative stress

Biology of disease (4 decks)

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