Biochem Final

Front 1

what does the term xeroderma mean

Back 1

atrophic and dry

Front 2

skin damage to patients with xeroderma pigmentosa results from which energy source

Back 2

ultra-violet light

Front 3

what is the most likely outcome in a patient with xeroderma pigmentosa

Back 3

2/3 die from metastatic dermatological cancer before adulthood

Front 4

which is the common defect in xeroderma, Cockayne syndrome, and trichothiodystrophy

Back 4

defect in nucleotide excision repair

Front 5

which part of the nucleotide excision repair process is most affected in individuals with complementation group A

Back 5

DNA damage recognition

Front 6

in nucleotide excision repair, the global genome repair pathway starts out with the action of which of the following gene products

Back 6

XPC/HR23B

Front 7

which gene products carry out the final steps of nucleotide excision repair

Back 7

DNA pol delta/epsilon and ligase

Front 8

the mean patient age for development skin cancer in a patient with xeroderma pigmentosa

Back 8

8 years

Front 9

the mean age for developing skin cancer in patient with Cockayne syndrome

Back 9

same as in the general population

Front 10

how is the diagnosis of a specific XP complementation group defect established

Back 10

assay of unscheduled DNA synthesis in UV-irradiation cultured fused fibroblasts

Front 11

which finding is most characteristic of gout in a 45-year old man with recurrent arthritis for over two decades

Back 11

tophi on ear cartilage

Front 12

which test is the most indicative of a hyperuricemia related arthropathy

Back 12

negative birefringent intracellular cystals in joint fluid aspirate

Front 13

which mechanism would most likely account for recurrent gout in a 62 year old man

Back 13

increased URAT1 activity

Front 14

a joint tape from a tender and swollen tow in a man that awakened from sleep the night after excessive drinking would likely show which cellular feature on microscopy

Back 14

predominance of polymorphonuclear neutrophil leukocytes with no bacteria

Front 15

an 18 year of with recurrent arthritis is diagnosed with hyperuricemia secondary to an enzyme defect, which enzyme is most responsible for this clinical manifestation due to a low Km value for the defective enzyme

Back 15

phosphoribosylpyrophosphate synthetase

Front 16

which enzyme defect is associated with Lesch-Nyhan syndrome

Back 16

hypoxanthine-guanine phosphoribosyl transferase deficiency (HGPRT)

Front 17

9 month old with delay in developmental milestones, dystonia, chorea and uric acid is elevated. what is the inheritance pattern most likely

Back 17

x-linked recessive

Front 18

what type of person has the highest likelyhood for developing gout

Back 18

65 year old man

Front 19

de novo purine synthesis is most dramatically stimulated by which substance

Back 19

alcohol

Front 20

27 year old man with sickle cell anemia develops left ankle arthritis. joint aspirate demenonstrates negatively birefringent crystals. what is the best management plan after NSAID therapy

Back 20

hydroxyuria to diminished hemolysis

Front 21

which enzyme of heme biosynthetic pathway is depressed to 50% of normal levels in acute intermittent porphyria

Back 21

porphobilinogen deaminase

Front 22

which enzyme of the heme biosynthetic pathway is subject to feedback inhibition by heme

Back 22

ALA synthase

Front 23

which intermediates of the heme biosynthetic pathway accumulate in acute intermittent porphyria (2)

Back 23

ALA
prophobilinogen

Front 24

what is the most frequent symptom of an acute attack of acute intermittent porphyria

Back 24

abdominal pain

Front 25

administration of which substrate is useful in treating mild attack of acute intermittent porphyria

Back 25

glucose

Front 26

attack of acute intermittent can be provoked by ingestion of alcohol due to induction of what enzyme depleting the liver heme pool

Back 26

cytochrome P450

Front 27

what is needed for porphyrin synthetsis

Back 27

Glycine
Succinyl-CoA
Vitamin B6

Front 28

what two enzymes do lead inhibit in heme synthesis

Back 28

ALA dehydratase
ferrochelatase

Front 29

how many ALA molecules condense to form one porphyrin ring

Back 29

8

Front 30

what is incorporated into the protoporphryin IX to make heme

Back 30

iron

Front 31

what clinical manifestations differentiate acute and cutaneous porphyrias

Back 31

acute - neurologic effects
cutaneous - photosensitivity

Front 32

uroporphyrinogen decarboxylase deficiency

Back 32

porphyria cutanea tarda

Front 33

porphobilinogen deaminase deficiency

Back 33

acute intermittent porphyria

Front 34

ferrochelatase deficiency in the erythtropoietic cells

Back 34

ferrochelatase

Front 35

major clinical feature of porphyria cutanea tarda

Back 35

skin photosensitivity

Front 36

clinical manifestations of acute intermittent porphyria

Back 36

abdominal pain, neuropathies, constipation, psychiatric symptoms

Front 37

disease in which protoporphyrin accumulates and leads to cutaneous photosensitivity and hepatobiliary disease

Back 37

erythropoietic protophyria

Front 38

heme synthesis pathway

Back 38

glycine + succinyl-CoA (ALA synthase) --> ALA + ALA (ALA dehydratase) --> porphobilinogen x 4 ( porphobilinogen deaminase) --> uroporphyrinogen (uroporphyrinogen decarboxylase)--> protoporporphyrin IX + iron (ferrochelatase) --> heme

Front 39

differentiate global genome repair and trancription-coupled repair

Back 39

GGR - eliminates lesion from the entire genome
TCR - specifically repair damage on DNA strands of actively transcribed genes

Front 40

what disease is associated with defect in transcription-coupled repair

Back 40

Cockayne syndrome

Front 41

disease associated with brittle hair and nails with tiger-tail pattern in hair

Back 41

trichothiodystrophy

Front 42

most common defect in gout

Back 42

renal under excretion due to increased urate reabsorption transporter (URAT1)

Front 43

3 way in which hyperuricemia can happen

Back 43

1. increased URAT1
2. increased PRPP synthetase
3. decreased HGPRT