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Biochemistry - step > FA 2015 > Flashcards

FA 2015 Flashcards

1
Q

describe de novo synthesis of pyrimidines

A

make temporary base - orotic acid
add sugar and phosphate
modify base

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2
Q

whats used to make pyrimidines

A

carbamoyl phosphate + aspartate

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3
Q

describe de novo synthesis of purines

A

start with sugar and phosphate

add base

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4
Q

whats used to make purines

A 
2x N10 formyl tetrahydroholate
glycine
glutamine
aspartate
CO2
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5
Q

leflunomide

A

carbamoyl phosphate –> X inhibits dihydroorate dehydrogenase X –> orotic acid

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6
Q

orotic aciduria

A

inhibits enzyme involved in conversion of orotic acid to UMP

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7
Q

hydroxyurea

A

UDP –> X inhibits ribonucleotide reductase X –> dUMP

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8
Q

5-flurouracil

A

dUMP –> X inhibits thymydilate synthase –> dTMP

decreased dTMP

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9
Q

methotrexate
trimethoprim
pyrimethamine

A

humans
bacteria
protozoa

DHF –> X inhibits dihydrofolate reductase X –> THF

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10
Q

6- MP

azithropurine

A

inhibites de novo purine synthesis

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11
Q

mycophenylate

ribavirin

A

IMP –> X IMP dehydrogenase X –> GMP

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12
Q

allopurinol

febuxostat

A

salvage purine pathway

hypoxanthine –> X inhibits xanthine oxidsase X –> xanthine –> X inhibits xanthine oxidase X –> uric acid

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13
Q

probenecid

A

uric acid –> INHIBITS –> urine

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14
Q

UGG

A

tryptophan - ony one codon = exception to degenerate/redundancy of the genetic code

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15
Q

AUG

A

methionine - only one codon = exception to degenerate/redundancy of the genetic code

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16
Q

describe DNA polymerase III

A

prokaryotic only
5’-3’ synthesis
3’-5’ exonuclease activity for proofreading

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17
Q

describe DNA polymerase I

A

prokaryotic only
5’-3’ synthesis to replace RNA primer with DNA
3-5’ exonuclease
5’-3’ exonuclease to get rid of RNA primer

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18
Q

Xeroderma pigmentosum - what goes wrong

A

defective ssDNA repair by UV light corrected by nucleotide excision (oligonucleotide removal, occurs in G1) – can’t fix pyrimidine dimers due to UV

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19
Q

HNPCC - what goes wrong

A

defective ssDNA repair by mismatch - errors that occur in synthesis that are corrected in G2

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20
Q

Ataxia telangiectasia and Fanconi Anaemia - what goes wrong

A

defective dsDNA repair by nonhomolougous end joining - correction of double stranded breaks (may lose genetic material, don’t need to be homologous)

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21
Q

Xermoderma pigmentosum - clinical presentation

A

predisposition to squamous cell carcinoma + basal cell carcinoma + malignant melanoma at an early age due to inability to repair pyridine dimers produced by exposure to UV light (nucleotide excision)

AR

numerous hyperpigmented lesions and nodular and scaly growthrs on face

goljan page 206 for pic

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22
Q

HNPCC - clinical presentation

A

increased risk of colorectal cancers without previous polyps; caused by germ line mutation in mismatch repair genes/G2 that cause a microsatellite repeat replication error/microsatellite instability – predispose to replication errors if there are mtuations in DNA repair enzymes/MMR genes – microsatellites become unstable (become longer or shorter) and produce RAMESHIFT mutatiosn that in activate or alter tumor suppressore gene function leading to cancer. MSI found in majority of HPMCC patients. :) try to not copy exact nedxt time becky :) its okay today bc you are a pukey face.

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23
Q

Ataxia telangiectasia - clinical presentation

A

increased risk of developing malignant lymphomas

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24
Q

Fanconi Anaemia - clinical presentation

A

can cause aplastic anaemia

don’t mess up with fanconi syndrome: polyuria, renal tubular acidosis type II, growth failure, electrolyte imbalances, hypophosphatemic rickets

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25
Q

what is fMet

A

AUG in bacteria - start codon
AND
stimulates neutrophil chemotaxis

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26
Q

list the stop codons pleease

A

journing of December till now
You go away UGA
You are away UAA
You are gone UAG

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27
Q

amantia phalloides!!!

A

inhibits RNA polymerase II - makes mRNA and can open NDA at promoter site

CXPX: four phases – asymptomatic – gi with diarrhoea and vomiting severe – apparent recovery – renal and liver failure in 7-10 days BCHM NOTES THROWBACK

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28
Q

rifampin

A

inhibits RNA polymerase in prokaryotes

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29
Q

Actinomycin D

A

inhibits RNA polymerase in prokaryotes and eukaryotes

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30
Q

whats the polyadenylation signal?

A

AAUAAA!!

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31
Q

sequence in the intron that splicesome makes a lariate out of

A

exon2 - OH - P - GU- A- AG - P - exon1

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32
Q

anti-spliceosomal snRNPs/antismith abs

A 
highly sensitive (rule out bc TN high)
SLE
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33
Q

anti-U1 RNP abs

A

highly associated with MCTD - mixed connective tissue disease

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34
Q

Define and give examples of permanent cells

A

remain in G0 + regenerate from stem cells

ex: neurons, skeletal muscle, cardiac muscle, red blood cells

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35
Q

Define and give examples of stable/quiescent cells

A

enter G1 from G0 when stimulated

ex: hepatocytes and leukocytes

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36
Q

Define and give examples of labile cells

A

nover go to Go, divide rapidly with a short Gi, most susceptible to chemotherapy
ex: bone marrow, gut epilthelium, skin, hair follicle, germ cells

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37
Q

Role of the Golgi

A

distribution centre for proteins and lipids from the ER to vesicles/plasma membrane or lysosome

N-oligosaccaharides are modified at ASPARAGINE
O-oligosaccharides are added to LYSINE and SERINE
addition of mannose-6-phosphate sends to lysosome for destruction

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38
Q

I cell disease pathophys

A

N-acetylglucosaminyl-1-phosphotransferase –> failure to phosphorylate mannose residues on glycoproteins in the Golgi –> are secreted extracellulary instead of trafficked to vesicles,

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39
Q

I cell disease cxpx

A 
coarse facial features
clouded corneas
restricted joint movement
high plasma level of lysosomal enzymes
often fatal in childhood
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40
Q

what causes proteins to accumulate in the cytosol that were produced in the RER (supposed to be secretory/vesicular proteins(

A

absent ro dysfunctional SRP/signal recognition particles - that shuttle the ribosome to the RER

41
Q

who cares about the peroxisome?

A

metabolism of VLCFA, branched FA, amino acids

42
Q

who cares about the proteasome?

A

degrades damaged or ubiquitin-tagged proteins

defects associated with some cases of Parkinson dz

43
Q

List drugs that affect microtubules

A 
Mebendazole - anti helminth
Griseofulvin - anti fungal
Colchicine - anti gout
Vincristine/vinblastine - anti cancer
Paclitaxel - anti cancer
44
Q

Karteneger Syndrome - clinical presentation

A 
infertility in men and women
increased risk of ectopic pregnancy in women
bronchiectasis
recurrent sinusitis
situs inversus (dextrocardia on CXR)
45
Q

what is oubain

A

inhibits the Na+K+ATPase by blocking the K binding site

46
Q

what is digoxin and digitoxin

A

inhibit the Na+K+ATPase –> indirectly inhibits the Na+Ca++ exchange –> increased intracellular Ca++ –> increased contractility at the heart.

47
Q

where do you find collagen I?

A 
bone
tendon
skin
cornea
fascia
late wound repair
dentin
48
Q

where do you find collagen II?

A

cartilage (hyaline too)
vitreous body @ eye
nucleus pulposus @ vertebrae

49
Q

where do you find collagen III?

A 
reticulin
skin
blood vessels
uterus
fetal tissue
granulation tissue
50
Q

where do you find collagen IV?

A

basement membrane
basal lamina
lens @ eye

51
Q

describe the types of collagen found in the eye

A

lens - IV
cornea - I
vitreous body - II

52
Q

Osteogenesis Imperfecta I

A

AD
defect synthesis of collagen I (bone, tendon, dentin, skin, fascia, cornea, late wound repair) - problems forming triple helix

53
Q

Ehlers-danlos, vascular type

A

defect in collagen III (reticulin, skin, blood vessels, uterus, fetus, granulation tissue) – problems in cross linking collagen

54
Q

Alport syndrome

A

defect in collagen IV (basement membrane, basal lamina, lens)

55
Q

List the diseases where collagen is affected

A

OI
Ehlers Danlos
Alport
Good Pasture

56
Q

Good Pasture

A

auto abs target type IV collagen (basement membrane, basal lamina, lens)

57
Q

Describe the CXPX of OI type I

A

aka brittle bone disease
blue sclera: due to the reflection of the underlying choroidal veins through the thin sclera
pathological fractures at birth
deafness in some patients

58
Q

CXPX of vascular type Ehlers Danlos

A

vascular and organ rupture
AD or AR
may be associated with joint dislocation, berry and aortic aneurysms, organ rupture
myxomatous degeneration can cause mitral valve prolapse (marfan too)

elastic skin + hypermobility of joints + increased bleeding tendency

goljan: hypermobile joints, aortic dissection (most common cause of death), mitral valve proplapse, bleeding into th eskin, ruture of the bowel, poor wound healing **can extend fingers so parallele with the extensor surface of the forearm - classical sign*

59
Q

cxpx fo Alport Syndrome

A

nephritic syndrome - hypertension, increased BUN and creatinine, oliguria, hematuria, RBC casts in urine, proteinuria usually < 3.5

hereditary nephritis + sensorineural hearing loss + cataracts
(type IV collagen defect: basement membrane, basal lamina, lens)

60
Q

OI again please, bit more organized this time

A

AD most commonly - decreased production of otherwise normal collagen type I (found at bone, skin, tendon, dentin, cornea, late wound healing).
sxs: MULTIPLE FRATURES with minimal trauma; may occur in birthing process + BLUE SCLERA due to the translucency of the connective tissue/sclera over the choroidal vessels + HEARING LOSS due to abnormal ossicles + DENTAL IMPERFECTIONS due to lack of dentin

61
Q

Ehlers Danlos again please, but more organized this time

A

inheritance AD/AR and varies in severity and type
a) most common - hypermobility of joints
b) classical - joints and skin = defect in type V collagen
c) vascular type - skin and blood vessels = defect in type III collagen (uterus, fetal tissue, skin, bv, granulation tissue)
due to faulty collagen synthesis; inability to cross-link tropocollagen

presents with a) hyperextensible skin b) tendency to bleed and c) hypermobile joints

compliccations include: a) joint dislocation b) berry aneurysm c) aortic aneurysm and d) oragn rupture

62
Q

Marfan Syndrome description time

A

AD fibrillin missense mutation chromosome 15
dilation fo ascending arota - dissection of aorta/aortic regurgitation; mitral valve prolapse – conduction defects = sudden death; CARDIO DEFECTS DOMINATE
hypermobile joints, dislocation of lens (suspensory ligament is made of elastin); eucunoid proportions (arms longer than body; lower body longer than upper), arachnodactyly/spider hands

63
Q

cxpx of aortic dissection

A

rfs: marfan, ehler danlos, HTN, pregos, coarctation of aorta

cystic medial degeneration - accumulation of breakdown products of elastin in the media
blood into weak points into the intima - will present as acute onset severe retrosternal chest pain radiating to the back; loss of upper extremity pulse due to compression fo subclavian artery by blood into the false lumen; can rupture into the pericardial sac, pleural or peritoneal cavities.

rupture usually occurs within 10 cm of AV
THORACIC @ marfans. abdominal — syphilis??

64
Q

amino acids in elastin?

A

nonhydroxylated (vrs collagen where lysine is OHd–requires vitamin C/scurvy) glycine, proline, lysine

65
Q

lab test for gene expression

A

northern blot

66
Q

confirmatory test for HIV after a positive ELISA

A

southern blot

67
Q

use of microarrays

A

can detect single SNPs
copy number variants
= genotyping, clinical genetic testing, forensic analysis, genetic linkage analysis, cancer mutations

68
Q

use fo karyotyping

A

chromosomal imbalances ie autosomal trisomies, sex chromosome disorders.

69
Q

uses of FISH

A

specific localization of genes and direct visualization of anomalies/microdeletions when karyotype cant detect something so small

70
Q

uses for the cre lox system

A

in ducibly manipulate genes at specific developmental points in order to study for example, a gene whose deletion causes embryonic death.

71
Q

McCune Albright Syndrome description please

A

mutation in G protein signalling that would be fatal if occurs before fertilization as it would affect all cells. Mosaicism after this permits survival.

CXPX: a) unilateral café-au-lait spots, b) polyostic fibrous dysplasia, c) precocious puberty, d) multiple endocrine abnormalities

72
Q

when would you suspect uniparental disomy

A

when an individual is showing a recessive disorder but only one parent is a carrier….so rare-zees

73
Q

CXPX of Prader Willi

A 
hypogonadism
hyperphagia -- obesity
short stature
neonatal hypotonia
intellectual disability
74
Q

CXPX of Angelman Sydnrome

A

jerky, wide stance with arm flapping - ataxia - marionette
outbursts of inappropriate laughter - happy puppet
severe intellectual disability
seizures

75
Q

Presentation of Mitochondrial Myopathies

A 
myopathy
lactic acidosis
CNS disease
ragged red fibres on muscle bipsy
ex: Leber Hereditary Optic Neuropathy and **myoclonic epilepsy
76
Q

newborn screening test for cystic fibrosis please

A

increased immunoreactive trypsinogen levels.

77
Q

confirm diagnosis of Duchenne muscle dystrophy

A

increased CPK and increased aldolase
western blot and muscle biopsy – will see fibrofatty replacement of skeletal and cardiac muscle due to lack of dystrophin connecting actin to alpha and beta dystroglycan leading to myonecrosis.

78
Q

CXPX of Duchenne muscle dystrophy

A

pelvic girdle muscle weakness first that moves progressively superiorly
pseudohypertrophy of calf muscles - fibrofatty replacement
Gower maneuver - used of arms to stand
waddling gait

79
Q

common cause of death in duchenne muscle dystrophy

A

dilated cardiomyopathy

80
Q

why is becker less severe than duchenneÉ

A

non frameshift insertions so dystrophin is partially functional instead of truncated.

81
Q

do deletions cause becker or duchenneÉ

A

both

82
Q

name the acrocentric chromosomes and their significance

A 
13,14,15,21,22
robertsonian translocation (long arms fuse at the centromeres if unbalanced -- miscarriage, stillbirth, chromosomal imbalances ie down syndrome or patau syndrome, etc.
83
Q 
severe intellectual disability
VSD
micrognathia
microcephaly
low set ears
prominent occiput
horeshoe kidney
rocker bottom feet
clenched fist with overlapping fingers
A

Edward Syndrome

Trisomy 18

84
Q 
severe intellectual disability
microcephaly/holoProsencephaly
rocker bottom feet
polydactyly
VSD
cystic/horeshoe kidneys
cleft liP/Palate
cutis aplasia
fatal within one year of brith
A

Patua syndrome
Trisomy 13

cutis aplasia - congenital absence of skin.

85
Q 
moderate to severe intellectual disability
microcephaly
epicanthal folds
VSD
high-pitched crying/mewing
A

Cri-du- chat
5p deletion
chromosome 5 also FAP

86
Q 
intellectual disability
hypercalcemia
well developed verbal skills
extreme friendliness to strangers
supravalvular aortic stenosis
''elfin'' facies
A

Williams syndrome
7q deletion
chromosome 7 also CF

87
Q

cleft palate
abnormal facies
cardiac defect

A

velocardiofacial syndrome
chromosome 22 microdeltion
problems with 3rd and 4th branchial pouches

88
Q

thymus aplasia - no T cells
cardiac defects
hypocalcemia - secondary to parathyroid absnece

A

digeorge syndrome
chromosome 22q11
problems with 3rd and 4th branchial pouches

89
Q 
skin lesions
oedema cause lower plasma oncotic pressure
liver malfunction causes it fatty 
anaemia
child with swollen abdomen
A

kwashiorkor - protein malnutrition
decreased protein intake
less apolipoproteins made is why fat accumulates in liver instead

90
Q

decreased subcutaneous fat
tissue and muscle wasting
child
variable oedema

A

marasmus

total calorie malnutrition

91
Q

describe the pathophysiology of each clinical presentation of chronic alcholsim of the following list:

a) lactic acidosis
b) fasting hypoglycemia
c) hepatosteatosis
d) ketoacidosis

A

a) lactic acidosis because pyruvate to lactate uses up an NADH (that is in excess from OH metabolism to acetate)
b) fasting hypoglycemia because oxaloacetate to malate uses up an NADH; oxaloacetate cannot be used for gluconeogenesis
c) hepatosteatosis: TCA stopped bc makes NADH so lipogenesis is favoured AND dihydroxyacetone phosphate to glycerol 3 phosphate uses up an NADH that then combines with 4 FA to form TAGS (remember tis the back bone of TAGs)
d) ketoacidosis due to elevated ketogenesis that is favoured when the TCA an NADH producint cycle is shut down.

hurrah.

92
Q

describe metabolism of OH in the peroxisome

A

alcohol –> + H2O2 with catalase –> acetaldehyde and water

93
Q

describe metabolism of OH in the cytosol

A

alcohol –> alcohol dehydrogenase with NAD –> acetaldehyde and NADH

94
Q

describe metabolism of OH in the microsome

A

alcohol –> NADPH with CYP2E1 –> acetaldehyte and NADPh

95
Q

describe metabolism of OH in the mitochondria

A

acetaldehyde –> NAD + acetaldehyde dehydrogenase –> NADH and acetate

96
Q

what is fomepizole

A

inhibits alcohol dehydrogenase in the cytosol

use for ethylene or methanol poisoning.

97
Q

list the metabolic pathways that occur in both the cytoplasm and the mitochoncria

A

heme synthesis
urea cycle
gluconeogenesis

98
Q

list the metabolic pathways that occur in the cytosol only

A 
glycolysis
fatty acid synthesis
HMP shunt
protein synthesis @ RER
steroid synthesis @ SER
cholesterol synthesis
99
Q

list the metabolic pathwyas that occur in the mitochondria only

A 
TCA cycle
ketogenesis
fatty acid beta oxidation
acetyl CoA production
oxidative phosphorylation

Biochemistry - step (4 decks)

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