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Medicine > IMS @ > Flashcards

IMS @ Flashcards

1
Q

Hyperthyroidism Symptoms

A

Hyperactive, sweating, lose weight, heat intolerance, palpitations, menstrual problems, hand tremors, goitre,
Periordenadema (swelling around eyes), proptosis (protrusion of the eyes) and paralysis of eye muscles can cause double vision

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2
Q

Diagnosis and treatment of hyperthyroidism

A

Static Test
Graves disease - thyroid peroxidase enzymes positive in 80% of cases and TSHR antibodies positive in 99% of cases!

Treatment - antithyroid drugs for 6-18months
Radioactive iodine - destroys thyroid gland, but not for pregnant, children, lactating women, urinary incontinent or those with active eye disease

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3
Q

Growth hormone defeciency symptoms

A

Children - failure of growth
Adults - tiredness, depression, often asymptomatic and requires no treatment

Diagnosis: Glucagon stimulation test - should raise GH as it stimulates its realease and Insulin stress test lowers BGL so should increase it

Treatment: Replace GH injections, but expensive

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4
Q

How do enzymes work?

A

1) Provide catalytically competent groups
2) Bind substrates in the right orientation
3) Stabilise transition substances

These all lower the activation energy of a reaction!

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5
Q

Active sites bind substrates via multiple weak interactions, e.g. Trypsin

A

Trypsin His57, Asp 102, Ser 195 (close together when folded)

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6
Q

Km

A

Describes the enzymes affinity to a substrate. High Km means a low affinity! Km = (k2 + k3 )/ k1

Km is the substrate concentration when Vmax = 1/2

If Km = [S] then V=Vmax/2

V=Vmax x [S]/([S]+Km)

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7
Q

Irreversible Inhibition

A

Covalent modification of active site

Iadoacetamide –> carboxymethylates cysteine side chains

Nerve agents e.g. Parathion, inhibits Achesterase and modifies serine residues

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8
Q

Competitive Reversible Inhibition

A

Enzyme binds to inhibitor or substrate but not both
High substrate overcomes inhibition
Vmax unchanged, Km Increased
Methotrexate competitively inhibits dihydrofolate needed for DNA/RNA synthesis

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9
Q

Non-competitive Inhibition

A

Enzyme binds to inhibitor and substrate as inhibitor doesn’t bind at active site
High substrate won’t overcome inhibition
Max decreased, Km stays the same
Alanine inhibits Pyruvate kinase

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10
Q

What do NADH, coA and Biotin carry

A

CO2

CoA carries acyl units, used with pantothenic acid (we must consume this acid)

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11
Q

Riboflavin defeciency

A

Ariboflavinosis

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12
Q

Niacin defeciency

A

Pellagra

Niacin acts as an electron donor to NADH

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13
Q

Thiamine defeciency

A

Beriberi

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14
Q

Vit C defeciency

A

Scurvy

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15
Q

Glucose-6-dehydrogenase defeciency

A

Commonest mutation, X-linked recessive
Enzyme is needed to produce large amounts of NADPH
Glucose –> Glucose 6 phosphate –> Pentose phophate pathway –> Ribose-5-phosphate which produces lots of NADP in the first step an important metabolic pathway to provide reducing power to erythrocytes
Mutation blocks NADP stops it being responsive to NADP levels
High incidence in malarial regions!
But causes primaquine-induced haemolytic anaemia!

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16
Q

Why do we need NADP?

A

NADPH refors glutathione (reduced), a scavenger molecule that reacts with free radicals
RBC’s have no mitochondria hence only make NADP via the glucose-6-deyhdrogenase pathway!
Primaquine reduces lots of free radicals (h202), not enough NADPH so the system can’t cope and RBCs can be killed by harmful molecules

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17
Q

Control of enzyme activity

A

1) Inhibition - often serine proteases
2) Feedback regulation
3) Covalent modification - phosphorylation used, often added to Ser or Thr
4) Proteolytic activation

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18
Q

What odo serpins inhibit

A

Serine proteases

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19
Q

What does trypsin cleave?

A

Cleaves the C terminal to lysine and arginine, prefers +ve charges, pancreatic trypsin inhibitors stop it

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20
Q

What does elastase do?

A

Elastase cleaves the C terminal to glycine and alanine!
Inhibited by alpha-1-antitrypsin
Secreted by neutrophils during inflammation to destroy bacteria

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21
Q

Tryspinogen

A

An enteropeptidase in the duodenum activates it by removing amino acids 1-6, causes a conformational shape change, can then cut itself into 3 chains held together by disulphide bonds

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22
Q

Thrombin

A

Prothrombin carried by platelets to site of injury
N-terminal of thrombin has carboxyglutamates, which bind to calcium on the platelet surface
However if no Vit K, prothrombin not in close contact with Xa & Va, thrombin isn’t released, fibrin isn’t released and blood can;t clot

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23
Q

Fibrinopeptides

A

These prevent fibrinogen reactions, normally removed by thrombin

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24
Q

Plasmin

A

Plasminogen converted to Plasmin by TPA (Tissue Type Plasminogen Activator)

Plasmin digests fibrin clot to small peptides

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25
Q

Fibrinogen

A

3 linked globular domains, middle domain contains 4 regions known as fibrinopeptides A&B which contain lots of negatively charged residues to prevent fibrinogen sticking together and clotting
Thrombin removes these fibrinopeptides!

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26
Q

Alzheimers

A

Fragments of the amyloid beta protein accumulate and aggregate in the brain causing insoluble plaques

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27
Q

CJD

A

Prione protein has identical primary sequence to normal proteins but a higher number of pleated sheets.
Prion causes normal protein to change structure
Insoluble aggregates accumulate causing a loss of neurological function

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28
Q

Haem Prosthetic group

A

Fe2+, and protoporphyrin IX held together by coordination bonds. Fe2+ is non-covalently bound into a hydrophobic crevice and it can coordinate with 6 ligands!
Haem keeps Fe2+ as Fe2+ not 3+ and prevents other molecules than oxygen binding!

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29
Q

Haemoglboin

A

2 alpha and beta chains, joined by non-covalent bonds, act as a tetramer of 2 pairs
Allosteric protein - binding of oxygen changes its shape
E&F helix pulled closetogether, protoporphyrin ring straightenes, proximal His H8 pulled in and salt bridges rupture

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30
Q

Bohr Effect

A

Low pH, H+ protonates residues (e.g. histidine), +ve charges form salt bridges, stabilise T states causing Hb to release oxygen

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31
Q

BPG

A

BPG binds in space between beta subunits in the T state, -ve charges on BPG react with +ve residues, stabilizes T state and reduces Hb affinity for O2

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32
Q

Foetal Hb

A

Binds BPG less, hence has a higher affinity for O2 than mothers blood so efficient transfer across the placenta!

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33
Q

Only 9 invariants in Hb

A

Proximal and distal His for o2 binding
Phe & Leu for Haem contact
Gly, Pro, Tyr - v. hydrophobic and important to maintain the structure!

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34
Q

Fibril forming collagen

A

1, 2 & 3

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35
Q

Netwrk forming collagen

A

IV, VII - forms the basal lamina

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36
Q

Fibril associated collaged

A

V, IX, XII involved in cross linking

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37
Q

Primary structure of collagen

A

Glycine every 3rd residue, Pro and lysine usually the other 2 aa
Hydroxyproline - needed for H bond to stabilise triple helix
Hydroxylysine - important for sugar attachment and cross linking and cross linking

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38
Q

Secondary collagen structure

A

Left hand helix - 3.3 residues per turn so tightly wound

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39
Q

Tertiary/Quartenary Structure

A

Triple helix tropocollagen in right hand twist!
Gly packed in centre, important as only enough room for H in the middle
Individual strands twisted in opposite directions, important for strength!

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40
Q

What forms in the fibroblasts

A

The pro collagen tirple helix!

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41
Q

Lysyl oxidase role in collagen

A

Dominates some of the lysine to allysine - allows cross links

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42
Q

Dupuytrens

A

A condition where too much collagen is produces, treat with collagenases

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43
Q

Osteogenesis Imperfecta (brittle Bones)

A

Mutation in type 1 collagen - often spontaneous, increases the risk of bone fracture

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44
Q

Ehlers Danlos Syndrome

A

Lysyl Oxidase defeciency

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45
Q

Scurvy

A

Lack of Vit C, lysyl and proudly hydrolyses can’t work, therefore no H bonds and cross linkings
Causes muscle weakness, joint tenderness, petichiae, tiredness, swelling/bleeding of gums!

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46
Q

Liver Damage

A

Increase in GPT & GOT

Later rise in Bilirubin

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47
Q

Prostatic Carcinoma

A

High Achid Phosphotases

High prostate specific antigens

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48
Q

Myocardial infarction

A

12 hours - peak in Creatinine Kinase
24 hours - peak in GOT
36 hours - Peak in Lactate Dehydrogenase

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49
Q

Lactate deydrogenase!§ a tetramer of 2, 35kDa subunits!

A

LDH1/H4 - Heart - allows aerobic respiration
H3M - monocytes/macrophages
H2M2- lungs
H1M3 - kidneys/pancreas
LDH5/M4 - liver/skeletal muscle - allows anaerobic respiration

LDH1:LDH2 measured, above 1 if heart attack occurs

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50
Q

Asparaginase

A

Converts asparagine to aspartate

Treats Childhood acute lymphoblastic leukaemia

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51
Q

Phenylketonuria

A

Give phenylalanine hydroxylase enzyme

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52
Q

Acatalassemia

A

Give catalase enzyme

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53
Q

Lesch-Nyhan syndrome (also a target for gene therapy)

A

Give HGPRT

54
Q

Smooth muscle disorder - leimyoma/fibroids

A

Benign growths in the female reproductive tract
Can cause heavy uterine bleeding and pain
More common in Afro-Caribbean

55
Q

Tubocurarine

A

Non-depolarising: Blocks ACh receptor, higher doses block the Na channels

56
Q

Succinycholine

A

Bonds to ACh receptor and depolarises

Causes paralysis as not metabolised as quickly as ACh

57
Q

Myasthenia Gravis

A

Antibodies produced against ACh receptors

58
Q

Lambert Eaton Sybdrom

A

Antibodies produced against Calcium channels, less ACh therefore released

59
Q

Amifamipradine

A

K+ channel blockers to prolong AP, treats lambert eaton syndrome!

60
Q

Wolf Parkinson White Syndrome

A

Extra conductive tissue from atria to ventricle causes supra ventricular tachycardia

61
Q

How does noradrenaline increase heart rate?

A

Increases cAMP, activates PKA, phosphorylates L type calcium channel so more Ca2+ released causing faster heart rate

62
Q

Digoxin

A

Blocks Na/K pump. Causes stronger contraction of heart

63
Q

Class I Arrythmia

A

Ventricular ectopics, Give Na blockers

64
Q

Arrhythmia class II

A

Beta blockers - treats low SA and AVN conduction and decreases the sympathetic effect

65
Q

Class III -

A

Potassium Blockers. treats ventricular tachycardia and AF

66
Q

Class IV

A

Calcium channel blockers, slows SA AND AV contraction. Reduces contractility of heart hence not appropriate for heart failure

67
Q

Duchenne Muscular Dystrophy

A

x linked recessive, mutation in dystrophin gene! causes muscle weakness etc.

68
Q

Tay Sachs Disease

A

Lysosome enzyme is lacking so sugar head on lipids isn’t cut back causing neurological problems

69
Q

Ganglioside a are a member of which family

A

The sphingolipids, they have very hydrophilic sugar groups so are exposed on the outer face of the membrane!

70
Q

rafts

A

Rich in cholesterol and sphingolipids (e.g. sphingomyelin) as they can pack closely with chilesterol!

71
Q

Linolic acid

A

essential for the Synthesis of some fatty acids

72
Q

Sphingolipids

A

ONLY IN THE OUTER LEAFLET

73
Q

do triacylyglycerols and cholesterol esters from membranes

A

NO they pack inside structures with one layer of phospholipids

74
Q

Alzheimer’s treatment

A

Cholinesterase inhibitors (Aricept, Exelon, Reminyl) and NMDA receptor antagonists (Ebixa) aim to increase stinulation across neurones to prevent neutron death

75
Q

Glyphorin A

A

In erythrocytes!

76
Q

`Bacteriorhodopsin

A

Pumps H ions across the membrane, 7TM alpha helixes with 20-30 amino acids in each helix

77
Q

Lipid linked membrane proteins

A

covalently attached to fatty acids in the membrane (e.g. glycosyl-phosphatidylinositol)
Also used for insulin receptor where palmetto locks insulin close to the membrane

78
Q

Peripheral membrane proteins

A

Don’t interact with hydrophobic core of bilayer, only interact with head groups or other membrane proteins through ionic attractions!

79
Q

O-linked sugars

A

Attached to hydroxyl groups in serine or threonine proteins residues

80
Q

N-linked sugards

A

Attached to side chain of asparagine residues but only in sequence Asn-X-Ser/Thr and X cannot be proline! Have large branded structure (30-40 residues)

81
Q

Blood antigens

A

N-acetyl-galactosamine in A

Galactose in B antigen

82
Q

Vancomycin

A

Transportsv vitamin K across the cell membrane as a carrier ionophore

83
Q

Gramicidin A

A

a permanent channel forming ionophore for the transfer of ions across the membrane

84
Q

Glucose transport into erythrocytes

A

Integral transporter with 12 TM helixes, brings glucose in then hexokinase adds phosphate to make glucose-6-phosphate hence conc. gradients aren’t wrecked

85
Q

Aquaporins

A

28kDa proteins with 6 TM sections for water reabsorption particularly in the kidneys

86
Q

Na/K ATPase enzyme

A

Has two alpha and two beta chains

87
Q

Cardiac Glycosides e.g. Digitalis

A

Inhibit Na/K pump, means less gradient for Ca/Na pump (usually 2 Ca out for 3Na in) so less calcium leaves the cell hence stronger heart contraction

88
Q

ORT

A

Contains salt and glucose! glucose lowers the water potential in the intestinal cells as it is absorbed hence treats diarrhoea!

89
Q

Which ions are directly coupled to ATP hydrolysis for membrane transport

A

Na, K, Ca, H.

90
Q

ApoA Lipoprotein

A

In HDL

91
Q

ApoB

A

In LDL, facilitates LDL uptake

92
Q

ApoC

A

Activates lipoprotein lipase

93
Q

ApoE

A

Stabilises VLDL

94
Q

FPP & GGPP

A

They are isoprenoids, add a small lipid tail to G proteins allowing them to attach to the cell membrane

95
Q

Rho effects

A

Crenelated by GGPP, increases adhesion molecules, thrombosis, cytokines and decreases vasodilation.

Hence statins also decrease endothelial dysfunction as they prevent the inflammatory responses that are also from Rho!q

96
Q

GPCR’s

A

7TM helixes, NH2 extracellular, COOH intracellularly, binding allows interaction of loop 3 with the G protein - leads to effect of G protein

97
Q

Renin-angiotensin system

A

Renin released by kidneys in low blood pressure or low Na+

98
Q

AT1 receptor effects

A

Vasoconstriction, increased Na secretion and reabsorption, aldosterone secretion. AT1 antagonists can treat heart failure!

99
Q

AT2 receptor effects

A

Opposes AT1, anti-hypertension, anti-hypertrophic

100
Q

Arginine + eNOS enzymes

A

Forms L-citrulline and NO

101
Q

Heme plus HO-1&2 enzymes

A

forms CO and Fe2+ + bilirubin

102
Q

Homecysteine + CBS, CSE, 3MST

A

H2S

103
Q

G protein mechanism

A

Binding of ligand - causes conformational shape change
Loop 3 can interact with G protein, GDP exchanged for GTP and it becomes activated
Alpha subunit dissosciates and moves downstream to activate the effector protein
Intrinsic GTPase activity of the G protein hydrolyses GTP to GDP and subunit deactivated

104
Q

Gs

A

Stimulates adenylate cyclase - raises cAMP - activates PKA

105
Q

Gi

A

Inhibits adenylate cyclase - lowers cAMP - less PKA activated

106
Q

Gq

A

Stimulates phospholipase C - PIP2 is converted into DAG & IP3 - IP2 diffuses through the endoplasmic reticulum causing increased Ca2+ release
DAG stays in the membrane and activates PKC

107
Q

Cholera

A

Inhibits GTPase activity of Gs, remains activated, increased cAMP, chloride channels stay open

108
Q

Whooping Cough

A

Pertussis toxin prevents GDP/GTP exchange in Hi, hence increased cAMP increases histamine and insulin secretion

109
Q

Caffeine and viagra are both…

A

PDE Inhibitors

110
Q

Angiotensin II binds to AT1R receptor and activates…

A

Gq protein activated

111
Q

Protein kinases only phosphorylate which residues

A

Serine, Threonine and Tyrosine
Serine & Threonine - by PKA, PKC, PKG
Tyrosine kinases - Insulin or Src
Map Kinase Kinases - phopsohrylate all 3

112
Q

Gleevex (Imatmib)

A

Tyrosine kinase used in treating chronic myeloid leukaemia,

113
Q

Neuropeptide or NO stimulates what

A

Activates gauntlet cyclase - produces cGMP - activates PKG

114
Q

ACh binds to muscarinic M2 receptor…

A

Gi activated, adenylate cyclase inhibited, lowers cAMP, less PKA activated

115
Q

Adrenaline binds to Beta1-AR…

A

Gs activated, adenylate cyclase stimulated, raises cAMP, more PKA activated

116
Q

What will make a membrane more fluid?

A

Decrease cholesterol, decreases length of fatty acid chain, increase number of saturated D bonds

117
Q

Why is D-glucose taken up much more readily than L-glucose in erythrocytes

A

As the glucose transporter has a much higher affinity for D glucose

118
Q

NFkB is a transcription factor, what happens when it binds to a gene promoter?

A

Transcription of that gene increases!

119
Q

Sphingolipids are only in the outer membrane of lipids true or false?

A

True

120
Q

What causes kinks in fatty acids

A

cis double bonds!

121
Q

Dyslipidaemias

A

mutations that affect the LDL receptor

122
Q

Throid blocking hormones

A

Cabrimazole and propylthiouracil!

123
Q

Epigenetics

A

Control of gene expression by means other than genetic variation

124
Q

Polymerase has 3 to 5’ proof reading activity, reduces errors to…

A

1 in 100 (10^5 to 10^7)

125
Q

Aspirin

A

Competitive irreversible, covalent modification of serine residue in COX-1

126
Q

Ibuprofen

A

Competitive reversible, binds to COX-1 active site but not covalently

127
Q

Mucin staining

A

Use Periodic Acid Schiff - stains mucin but also glycogen, hence apply diastase enzyme to remove glycogen before PAS added

128
Q

Marfans Syndrome

A

A lack of fibrillin

129
Q

Pyruvate –> Acetaldehyge

A

Pyruvate Carboxylase catalyses this (needs biotin)

130
Q

Acetaldehyde –> ethanol

A

Alcohol dehydrogenase catalyses this (uses NADH)

131
Q

Seligline

A

Treats Parkinsons

Medicine (22 decks)

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