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General Principles > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

Components of the nucelosome

A

DNA wrapped around a large histone
H1 histone linker connects them
DNA negative with phosphate groups
Histone are LARGe and positive from lysine and arginine

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2
Q

What is heterochromatin

A

Highly condensed (HeteroChromatin)
Dark, less visible on EM
Deactivates transcription

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3
Q

What is Euchromatin

A

Euchromatin is expressed
Active, more visible on EM
Transcriptionally active

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4
Q

What is visible and non-visible on EM stain

A

Euchromatin visible
Heterochromatin less visible (dark)

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5
Q

Function of DNA methylation

A

Adds methyl groups to DNA which changes the expression of DNA without altering the sequence
Deactivates DNA

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6
Q

Condition with dysregulated DNA methylation

A

Fragile X syndrome

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7
Q

What is histone acetylation

A

Acetylation makes DNA active
Activates transcription

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8
Q

What is histone deacetylation

A

Removal of acetyl groups - deactivates DNA, by reducing transcription

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9
Q

What condition is associated with histone acetylation

A

Thyroid fisorders
Thyroid hormone synthesis can be altered by acetylation

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10
Q

What condition is associated with histone deacetylation

A

Huntingtons disease

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11
Q

What amino acids are purine and pyramidines

A

Purines - A, G
Pyramidines - C, U, T

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12
Q

Deamination reaction of;
Guanine, cytosine, 5 methylcystine, adenine

A

Cystosine - uracil
Guanine - xanthine
Adenine - hypoxanthine
5 methylcystine - thymine

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13
Q

Drugs that affect pyramidine synthesis

A

Leflunomide - dihydrooate dehydrogenase
5- flurouracil - thymidylate synthesis

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14
Q

Drugs affecting purine synthesis

A

5 mercaptopurine - de novo purine synthesis
Mycophenalate and ribavirin - inosine monophosphate dehydrogenase

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15
Q

Drugs that affect both purine and pyramidine synthesis

A

Methotrexate, TMP, pyramethamine - dydrofolate reductase
Hydroxyurea - ribonucleotide reductase

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16
Q

Condition caused by impaired nucleotide excision repair

A

Xeroderma pigmentosum

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17
Q

Types of DNa repair and where they occur in the cell cycle

A

Nucleotide excision repair - G phase
Base excision repair - throughout
Mismatch repair - S phase

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18
Q

Condition caused by impaired DNA repair - non homologous end joining

A

Ataxia telangectasis

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19
Q

Condition caused by impaired DNa repair - homologous recombination

A

BRCA 1 and 2 + fanconi syndrome

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20
Q

Function of helicase

A

Helicase halves DNA at replication fork

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21
Q

Function of primase

A

Primes RNA for DNA to initiate replicarion

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22
Q

Function of telomerase

A

Adds TTAGGG to avoid loss of materal with duplication
Telomerase TAG’s for Greatness and Glory

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23
Q

Types of DNA repair

A

Single stranded
- nucleotide excision repair (G phase)
- base excision repair (throughout)
- mismatch repair (S phase)
Double stranded
- homologous recombination
- non-homologous end joining

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24
Q

What is a transition mutation

A

Purine - purine or pyramidine to pyramidine change

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25
Q

Silent mutation

A

Same codon

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26
Q

Missense mutation

A

Changed amino acid

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27
Q

Nonsense mutation

A

Stop in codon, non functioning protein

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28
Q

Condition caused by missense mutation

A

Sickle cell

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29
Q

Conditjons caused by frameshift mutation

A

Cystic fibrosis, taysaxhs, duchenne muscular dystrophy

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30
Q

Conditiond caused by splice site mutation

A

Marfans, beta thalassaemia, gauchers

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31
Q

RNA polymerases - eukaryotes

A

RNA polymerase I - rRNA
RNA polymeraze II - mRNA, miRNA, snRNA
RNA polymerase III - tRNA, 5s RNA

rNA MIght Maintain Small Nucleus by 5pm Tonight

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32
Q

RNA polymerases - prokaryotes

A

1 RNA polymerase - all kinds of

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33
Q

Sequence of protein synthesis

A

Initiation - elongation - termination

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34
Q

What are the 2 types of post translational modifications

A

Trimming
Covalent alterations

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35
Q

Trypsinogen to trypsin is what type of post translational modification

A

Trimming

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36
Q

Phosphorylation is what type of post translational modification

A

Covalent alteration

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37
Q

pathophysiology of Lesch Nyhan syndrome

A

defective purine salvage (utilizes folate/vitamin D)
absent HGPRT

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38
Q

features of lesch nyhan syndrome

A

caused by absent HGPRT
Hyperuriciaemia
Gout
Pissed off (self mutilation)
Rred/orange crystals in urine
Tense muscles (dystonia)
also megaloblastic anaemia due to low folate and b12

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39
Q

phases of the cell cycle are regulated by what?

A

cyclins, cyclin dependant kinases, and tumour suppressor genes

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40
Q

where does n-linked glycosylation occur?

A

rough endoplasmic reticulum
‘N-linked eNdoplasmic’

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41
Q

function of rough endoplasmic reticulum

A

site of synthesis of secretory (exported) proteins, N-linked oligosaccharides, lysosomal and other proteins

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42
Q

function of smooth endoplasmic reticulum

A

site of steroid synthesis and detoxification of drugs and poisons
‘gets rid of bad stuff to make it smooth and nice’
(lacks surface ribosomes which makes it smooth)

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43
Q

what cells are rich in smooth endoplasmic reticulum?

A

hepatocytes and steroid hormone producing cells of the adrenal cortex and glands
(function is for steroid synthesis and detoxification of drugs and poisons)

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44
Q

what are the vesicular tracking proteins

A

carry material from ER to golgi appartatus or from golgi to ER
COPI - retrograde (golgi to ER)
COPII - antegrade (ER to golgi)
2 steps forward, 1 step back
clathrin - trans golgi

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45
Q

pathophysiology of adrenoleukodystrophy

A

x-linked recessive disorder of beta-oxidation due to mutation of the ABCD1 gene of peroxisomes
results in a build of VLCFA in adrenal glands

46
Q

what type of immune responses are proteasomes responsible for?

A

MHC-1 mediated

47
Q

function of cystoskeleton filaments;
microfilaments
intermediate filaments
microtubules

A

microfilaments - muscle contraction
intermediate filaments - maintains cell structure
microtubules - movement, cell division

48
Q

pathophysiology of primary cilliary dyskinesia

A

autosomal recessive
Dynein arm defect

49
Q

features of primary ciliary dyskinesia

A

situs inversus
hearing loss
recurrent chest infections
infertility - ectopic pregnancys

50
Q

how does digoxin affect ATP pump

A

inhibits atp pump so directly inhibits Na/Ca exchange resulting in increased Ca = increased cardiac contractility

51
Q

Na and K movement in Na/K Atp pump

A

3 K in
2 Na out

52
Q

4 types of collagen and where each are most commonly found

A

1 - skeletal, skin, tendon, Late wound repair
2 - cartillage, vitreous humour
3 - arteries, skin, uterus, foetal, Early wound repair
4 - basement membrane (glomerulus, cochlea), lens
5 - interstitial tissue, placenta

53
Q

what type of collagens are involved in early and late wound repair

A

early type 3 collagen
late type 1 collagen

54
Q

type of collagen affected in ehlors danlos syndrome

A

classical type (skin and joint symptoms) -> type V
vascular type (SAH, aneurysms) -> type III

55
Q

whats the genetic term to describe the BRCA 1gene

A

incomplete penetrance
(not everyone with the BRCA1 gene will develop ovarian or breast cancer)

56
Q

whats the genetic term to describe huntingtons disease

A

anticipation
increased severity or earlier onset with each succeeding generation

57
Q

what is allelic heterogenicity and a condition it is found in

A

different alleles in the same locus result in the same disease
beta-thalassaemia

58
Q

what conditions are an example of imprinting

A

prader willi and angleman syndrome

59
Q

in prader willi, disease occurs when maternal or paternal derived gene is silenced or mutated?

A

paternal

60
Q

in angleman syndrome, disease occurs when maternal or paternal derived gene is silenced or mutated?

A

maternal

61
Q

chromosome involved in prader willi and angleman syndromes?

A

chromosome 15

62
Q

chromosome affected in haemochromatosis

A

6

63
Q

chromosome affected in ADPKD and huntingtons

A

4

64
Q

chromosome affected in renal cell carcinoma and von hippel lindau

A

3

65
Q

chromosome affected in williams syndrome and CF

A

7

66
Q

chromosome affected in wilsons disease and patau syndrome

A

13

67
Q

what chromosome is affected in FAP

A

5

68
Q

chromosome affected in BRCA 2

A

13

69
Q

chromosome affected in marfans syndrome

A

15

70
Q

what part of the brain is affected in wernickes-korsakoffs syndrome

A

dorsal nucleus of thalamus

71
Q

FAD and FMN are derived from what vitamin

A

B2 (riboflavin)

72
Q

NAD and NADP are derived from what vitamin

A

B3 (niacin)

73
Q

what vitamin is a component of coenzyme A (COA)

A

B5

74
Q

what vitamin is a component of pyridoxal phosphate (PLP)

A

pyridoxine (B6)

75
Q

features of zinc deficiency

A

delayed wound healing
suppressed immunity
male hypogonadism
reduced adult hair
anosmia
acrodermatitis enteropathica (occurs at openings i.e. perianal)

76
Q

antedote for alcohol overdose and mode of action

A

fomepizole
(competitive inhibitor of alcohol dehydrogenase)

77
Q

mode of action of disulfiram

A

inhibits acetaldehyde deydrogenase which increases acetaldehyde = increased hangover symptoms

78
Q

resting phase of cell cycle

A

G0

79
Q

what phase of the cell cycle determines the length of the cycle

A

G1 phase

80
Q

what phase of the cell cycle is the shortest

A

mitosis

81
Q

what phase of the cell cycle does DNA, RNA and histone synthesis occur

A

S phase

82
Q

what are the 2 main regulators of Ca in the body

A

PTH and calcitriol (active form of vit D)

83
Q

what enzyme is responsible for the phsophorylation of glucose to glucose-6-phosphate

A

glucokinase

84
Q

rate limiting enzyme of glycolysis

A

phosphofructokinase-1 (fructose-6-P to fructose-1,6,biphosphate)
glucokinase/hexokinase (glucose to glucose-6-P)

85
Q

rate limiting enzyme of cholesterol synthesis

A

HMG-COA reductase

86
Q

rate limiting enzyme of ketogenesis

A

HMG-COA synthase

87
Q

rate limiting enzyme of lipolysis (fatty acid oxidation)

A

carnitine acyltransferase I

88
Q

rate limiting enzyme for HMP shunt (hexose monophosphate shunt)

A

glucose-6-phosphate dehydrogenase

89
Q

vitamin C is responsible for production of what proteins and enzyme?

A

proline and lysine in collagen synthesis
dopamine beta-hydroxylase (dopamine to NE)

90
Q

what vitamin helps absorption of iron suplements?

A

ascorbic acid (vit C)

91
Q

NAD and NADP are derived from what vitamin ?
are they used in anabolic or catabolic processes ?

A

vitamin B3 (niacin)
NAD - catabolic
NADP - anabolic (fatty acid and steroid synthesis)

92
Q

function of glucokinase and where is it found

A

converts glucose to glucose-6-phosphate
found in liver
hexokinase converts this in other tissues

93
Q

what enzyme catalyses glucose to glucose-6-phosphate

A

glucokinase in liver and b cells in pancrease
hexokinase in other tissues

94
Q

feedback inhibitor for glucokinase and hexokinase

A

both convert glucose to glucose-6-phosphate
glucokinase inhibited by fructose-6-phosphate
hexokianse inhibited by glucose-6-phosphate

95
Q

is glucosekinase and hexokinase induced by insulin

A

glucoskinase yes
hexokianse no

96
Q

does PFK or FBP increase during gluconeogenesis?

A

FBP increases in gluconeogenesis
PFK decreases
FaBien the Peasant works hard when starving
Prince FederiK only works when fed

97
Q

what cofactor does arsenic inhibit ?
what is the function of this cofactor ?

A

lipoic acid
cofactor for 3 enzymes in the mitochrondri that link glycolysis to TCA cycle

98
Q

cofactors required in the pyruvate dehydrogenase complex in the mitochondria
(pyruvate +NAD +CoA -> NADH + acetylCoA + C02)

A

The Lovely Coenzymes For Nerds
Thiamine (B1)
Lipoic acid
CoA (B5 pantothenic acid)
FAD (B2 riboflavin)
NAD (B3 niacin)

99
Q

in pyruvate dehydrogenase deficiency, what lab serum lab finding would there be?

A

increased serum alanine

100
Q

gluconeogenesis irreversible enzymes

A

pathway produces fresh glucose
pyruvate carboxylase
phosphoenolpyruvate carboxylase
fructose-1,6, biphosphatase 1
glucose 6 phosphate

101
Q

main inhibitory neurotransmitter in the brain

A

GABA (glycine in spinal cord)

102
Q

main inhibitory neurotransmitter in the spinal cord

A

glycine (GABA in brain)

103
Q

Glycine can be synthesised from what essential amino acid

A

serine

104
Q

glycine causes inhibition through what receptors

A

NMDA (prevents glutamate-mediated depolarisation via NMDA receptors at post synaptic terminal)

105
Q

glycine is used as an intermediate in the synthesis of what proteins

A

porphyrins and purines

106
Q

G-6-P deficiency results in a build up of what amino acid

A

glutathione

107
Q

features of hartnup disease

A

rare secondary form of pellagra
sun exposed dementia
diarrhoea
dementia (incl nystagmus, ataxia, )

108
Q

hartnup disease results in elevated level of what amino acid in the urine

A

tryptophan (due to reduced abroption in the kidney and gut)

109
Q

hartnup disease results in what vitamin deficiency

A

niacin (B3) due to tryptophan deficiency

110
Q
A

General Principles (3 decks)

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