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Biochemistry 3.0 Flashcards

1
Q

what is the function of glucose-6-phosphate in the HMP shunt

A

G6P reduces NADP to NADPH which in turn reduces glutathione via glutathione reductase. GSH - the reduced form of glutathione protects against oxidative stress
therefore in G6P deficiency, glutathione is not reduced to GSH so theres no protection

will result in raised levels NADP and glutathione but low NADPH and GSH

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2
Q

features of porphyria cutanea tarda

A

tea coloured urine
chronic but mildly elevated transaminases
bullae/blistering of skin exposed areas of skin

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3
Q

defective enzyme in porphyria cutanea tarda and where this is found in the cell

A

UROD enzyme found in the cytoplasm

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4
Q

what co-factor does aminolevulinate synthase require

A

pyridoxine B6

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5
Q

what would a deficiency in aminoleuvilinate synthase may cause

A

sideroblastic anaemia and cheilosis

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6
Q

what would a deficiency in homocysteine methyltransferase cause

A

megaloblastic anaemia

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7
Q

co factor for homocysteine methyltransferase

A

vitamin B12

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8
Q

what cofactor does pyruvate carboxylase require

A

biotin B7

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9
Q

what cofactor does alpha-ketoglutarate dehydrogenase cause

A

vitamin B12

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10
Q

what would a deficiency in alpha-ketoglutarate dehydrogenase cause

A

wernickes encephalopathy

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11
Q

pyruvate dehydrogenase deficiency would cause a build up of what substances

A

lactate (vie LDH) and alanine (via ALT)

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12
Q

features of pyruvate dehydrogenase deficiency

A

results in a build up of pyruvate which gets shunted to lactic acid (via LDH) and alanine (via ALT)

causes neurological defects, lactic acidosis and rise in serum alanine in infancy

treat with ketogenic diet (high fat content, high lysine and leucine), B1 and lipoic acid

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13
Q

a diet high in what amino acids should be in a patient with pyruvate dehydrogenase deficiency

A

leucine and lysine

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14
Q

conditions with defect in breakdown of glycosaminoglycans

A

hurler and hunter syndromes
(mucopolysaccharides in urine)

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15
Q

conditions with defect in metabolism of essential amino acids

A

maple syrup disease (alpha ketoacids)
phenylketonuria (phenylketones)

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16
Q

condition with defect in protein tagging at the golgi apparatus

A

I-cell disease

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17
Q

bleeding disorder with elevations of both PT and APPT with history of prolonged exposure to antibiotics

A

vitamin K deficiency (defect in carboxylation of glutamic acid residues by glutamyl carboxylase)

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18
Q

what vitamin is required to activate vitamin K dependant clotting factors

A

vitamin C

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19
Q

hydroxylation of proline residues requires what coenzyme

A

vitamin C

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20
Q

enzymes affected in lead poisoning

A

ferrochelatase + aminolevulinate dehydratase
(required enzymes in haem synthesis = microcytic anaemia)

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21
Q

lead poisoning causes a build up of what substances

A

aminovulinate and protoporphyrin

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22
Q

converts ganglioside M2 to ganglioside M3

A

tay-sachs (hexosaminase deficiency)

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23
Q

converts glucocerebroside to ceramide

A

gauchers (beta-glucocerebrosidase deficiency)

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24
Q

converts galactocerebroside to ceramide

A

krabbes (galactocerebrosidase deficiency)

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25
ceramide trihexoside to lactosyl cerebroside
fabrys (alpha galactosidase deficiency)
26
classic galactosaemia results in a rise of what substances
galactitol and galactose-1-phosphate caused by defieincy in the enzyme GALT jaundice, hepatomegaly, failure to thrive
27
what is the main component of surfactant
phosphatidylcholine 'lecithin'
28
what type of pneumocytes is surfactant produced from
type 2 pneumocytes (cuboidal, columnar)
29
features of maple syrup disease
impaired breakdown of alpha ketoacids (Leucine, isoleucine and valine) due to deficient apha ketoacid dehydrogenase Alpha ketoacids in urine presents with sweet smelling urine, poor feeding, hypo/hypertonia, vomiting
30
features of pompes disease
due to alpha 1,4 glucosidase deficiency hypotonia, hepatomegaly, macroglossia, heart murmur, cardiomegaly
31
what is the rate limiting step of glycolysis
phosphofructokinase
32
what substance inhibits the rate limiting step of glycolysis
citrate --> this will reduce production of pyruvate from glucose
33
what is a precursor to thyroid hormone
tyrosine --> phenylalanine
34
deficient enzyme in PKU
tetrahydrobiopterin (co-factor for Phenylalanine hydroxylase) malignant PKU --> DHPR
35
the deficient enzyme in McArdles is found in what part of the cell
cytosol
36
what vitamin K clotting factor has the shortest half life
vitamin VII
37
how do non-competitive inhibitors affect Km and VMAX
non-competitive inhibitors decrease VMAX but no effect on Km (decreased reaction rate (vmax) but no effect on affinity)
38
how do competitive inhibitors affect Km and VMAX
compeitive inhibitors increase Km but no effect on VMAX (decreased affinity but no change in
39
what type of inhibitor can be overcome by increasing concentration of substrate
comptitive inhibitors
40
infantile cataract with hepatomegaly
(glucose-1-phsophate uridyltransferase GALT deficiency) classic galactosaemia
41
infantile cataracts without hepatomegaly
galactokinase deficiency
42
what motor protein is involved in retrograde transport
dynein (within microtubules)
43
what motor protein is involved in antegrade transport
kinesin (within microtubules)
44
what effects would a deficiency in glutamate decarboxylase cause
glutamate decarboxylase converts glutamate to GABA which is responsible for inhibiting neurotransmitters in the brain = increased seizure activity/neuro excitability
45
what vitamin protects cell membranes from oxidative damage
vitamin E
46
vitamin deficiency responsible for angular cheilitis
vitamin B2 (riboflavin) (derived from FAD and FMN)
47
what electron carried is used in steroid synthesis
NADPH
48
describe how intoxication of ethanol can cause hypoglycaemia
NAD is converted to NADP during ethanol metabolism. the resulting increase in NADP:NAD ratio in the liver leads to inhibition of gluconeogenesis and resulting hypoglycaemia
49
where in the cell is insulin synthesised
rough endoplasmic reticulum
50
describe pathophysiology of chronic granulomatous disease
CGD is caused by a lack of NADPH oxidase, a key enzyme used by neutrophils to destroy pathogens via respiratory burst. NADPH oxidase uses oxygen as a substrate to produce superoxide anion, which is used to generate hydrogen peroxide and ultimately hypochlorous acid.
51
what substrate is required for the deficient enzyme in chronic granulomatous disease
oxygen is the substrate for NADPH
52
rate limiting step of urea cycle
carbomyl phosphate synthesis
53
rate limiting step of glycogenolysis
glycogen phosphorylase
54
rate limiting step of ketogenesis
HMG CoA synthase
55
rate limiting step of lipolysis (breakdown of adipose tissue to fatty acids)
hormone sensitive lipase
56
rate limiting step of fatty acid oxidation
carnitine acetyltransferase
57
rate limiting step of fatty acid synthesis (lipogenesis)
(citrate shuttle) acetyl CoA carboxylase
58
rate limiting step of HMP shunt
glucose-6-phosphate dehydrogenase
59
what type of channel receptors are used in myaesthenia gravis
Ligand gated ion channels
60
what is a co factor in the synthesis of GABA
pyridoxine (B6)
61
where in the cell does beta oxidation of fatty acids occur
b oxidation is the breakdown of fatty acids occurs in mitochondria
62
long chain fatty acids are transferred to the mitochondria via what shuttle? what is the rate limiting enzyme?
carnitine shuttle carnitine acetyltransferase
63
where in the cell does fatty acid synthesis take place
cytosol
64
role of malonyl CoA in fatty acid oxidation
inhibits carnitine acetyltransferase therefore inhibiting fatty acid oxidation
65
role of citrate and palmitoyl CoA in fatty acid synthesis
citrate activates fatty acid synthesis (via activation of acetyl CoA carboxylase) palmitoyl CoA inhibits
66
rate limiting step of glycolysis
phosphofructokinase-1
67
rate limiting step of gluconeogenesis
fructose-1,6- biphosphate
68
rate limiting step fo TCA cycle
isocitrate dehydrogenase
69
rate limiting step of glycogenesis
glycogen synthase
70
rate limiting step of de novo pyramidine synthesis
carbomyl phosphate syntahse II
71
rate limiting step of de novo purine synthesis
glutamade phosphoribosylpyrophosphate (PRPP) amidotransferase
72
what enzymes are vitamin b7 (biotin) cofactors for
cabroxylation enzymes; pyruvate carboxylase acetyl CoA carboxylase priopionyl carboxylase
73
what amino acid and co factor are used for the production of GABA and glutathione ?
glutamate and pyridoxine (B6)
74
what amino acid and co factors are required for the production of serotonin and melatonin
tryptophan and BH4, pyridoxine (B6)
75
what amino acid and co factors are required for the production of niacin? what is niacin a precursor to?
trytophan, B6 (pryidoxine) and B2 (riboflavin) niacin is a precursor to NAD and NADP
76
difference in von gierkes vs corris disease
von gierks --> glucose 6 phosphate deficiency corri's --> debranching enzymes alpha glucosidase corri's has milder symptoms and normal blood lactate level
77
oxidative decarboxylation of pyruvate requires what cofactor
vitamin B1 (pyruvate to acetyl CoA by pyruvate dehydrogenase complex)
78
describe how PTH increases Ca through increasing osteoclast activity
indirect stimulation of osteoclast activity through osteoblast-mediated release of cytokines
79
blotting procedures
southern blot = DNA northern blot = RNA western blot = protein
80
what substance is required to aid in absorption of non-haem iron in the gut
vitamin C
81
G1 phase
cells divide and replicate through the cell cycle
82
S phase
DNA replication
83
G2 phase
preparing for mitotis
84
the defective enzyme in maple syrup disease requires what co factor
alpha ketoacid dehydrogenase require thiamine pyrophosphate (B1)
85
amino acids involved in the first step in haem synthesis
glycine + succinyl-CoA = aminolevulinic acid
86
site of O-linked glycosylation
golgi apparatus
87
how does hypokalaemia cause metabolic alkalosis
low levels of K cause K to shift outside the cells. In compensation hydrogen ions enter the cells to maintain neutrality = alkalotic

General Principles (13 decks)

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