Biochem

Question 1

α-amanitin

Answer 1

• found in death cap mushroom.
• inhibits RNA pol 2 (makes mRNA).
• hepatotoxic.

Question 2

P-bodies

Answer 2

• mRNA quality control.
• cytoplasmic.
• contain exonucleases, decapping enzymes, and microRNAs
• mRNAs may be stored here for future translation.

Question 3

spliceosomal snRNPs

Answer 3

• Abs against these = anti-smith Abs

- specific for SLE

Question 4

Trimming

Answer 4

• post-translational modification.

- Removal of N- or C-terminal propeptides from zymogen to generate mature protein (e.g., trypsinogen to trypsin).

Question 5

Ingredients to make Niacin (B3)

Answer 5

Tryptophan
B2 (riboflavin)
B6 (pyridoxine)

Question 6

Base excision repair

Answer 6

1-glycosylase = strips off base
2-endonuclease = cleaves 5' end
3-lyase = cleaves 3' end
4-DNA pol
5-ligase

Question 7

Enhancers and silencers (of gene expression)

Answer 7

Variable locations

Question 8

COP1

Answer 8

Retrograde

• Golgi => Golgi
• Golgi => ER

Question 9

COP2

Answer 9

Anterograde

• Golgi => Golgi
• ER => Golgi

Question 10

Ribozyme (rRNA)

Answer 10

Catalyzes peptide bond formation btwn amino acids

Question 11

Ouabain

Answer 11

Inhibits Na/K ATPase by binding to K site.

Question 12

Type 3 Cartilage

Answer 12

Reticulin:

• blood vessels
• uterus
• fetal tissue
• granulation tissue

Question 13

Problems forming triple helix in RER (collagen).

Answer 13

Osteogenesis imperfecta

Question 14

Problems cross-linking collagen (lysyl oxidase)

Answer 14

Ehlers Danlos

Question 15

Menkes Disease

Answer 15

• CT disease
• impaired copper absorption and transport.
• leads to dec. lysyl oxidase activity (cross links collagen)
• brittle, “kinky” hair, growth retardation and hypotonia.

Question 16

Pleiotropy

Answer 16

One gene contributes to multiple phenotypic effects.

ie. PKU

Question 17

Dominant negative mutation

Answer 17

Exerts a dominant effect. A heterozygote produces a nonfunctional altered protein that also prevents the normal gene product from functioning.
-Mutation of a transcription factor in its allosteric site. Nonfunctioning mutant can still bind DNA, preventing wild-type transcription factor from binding.

Question 18

McCune-Albright syndrome

Answer 18

-lethal if themutation is somatic, but survivable if mosaic.
-polyostotic fibrous dysplasia with cafe-au-lait skin
pigmentation and endocrinopathies.

Question 19

Locus heterogeneity

Answer 19

Mutations at different loci can produce a similar
phenotype.
-ie. albinism

Question 20

Allelic heterogeneity

Answer 20

Different mutations in the same locus produce the same phenotype.
-ie. beta-thal

Question 21

Heteroplasmy

Answer 21

Presence of both normal and mutated mtDNA, resulting in variable expression in mitochondrial inherited disease.

Question 22

Heterodisomy

Answer 22

meiosis 1 error

Question 23

Isodisomy

Answer 23

meiosis 2 error

Question 24

Prader-Willi & angelman

-which chromosome?

Answer 24

15

-or uniparental disomy. Inherit two methylated copies.

Question 25

Hypophosphatemic rickets

Answer 25

Formerly known as vitamin D–resistant rickets. Inherited disorder resulting in  phosphate wasting at proximal tubule. Results in rickets-like presentation.

Question 26

Mitochondrial myopathies

Answer 26

rare disorders; often present with myopathy, lactic acidosis and CNS disease. 2° to failure in oxidative phosphorylation. Muscle biopsy often shows “ragged red fibers.”

Question 27

FAP | -which chromosome?

Answer 27

5 | -5 letters in "polyp".

Question 28

Osler-Weber-Rendu Syndrome

Answer 28

aka Hereditary hemorrhagic telangiectasia - Inherited disorder of blood vessels. - Findings: telangiectasia, recurrent epistaxis, skin discolorations, arteriovenous malformations (AVMs), GI bleeding, hematuria.

Question 29

NF1 | -which chrom?

Answer 29

17 | -17 letters in “von Recklinghausen.”

Question 30

NF2 | -which chrom?

Answer 30

22 | -NF2 = 22

Question 31

VHL | -which chrom?

Answer 31

3 | -VHL = 3 letters

Question 32

Hardy Weinberg

Answer 32

The frequency of an X-linked recessive disease | in males = q and in females = q^2.

Question 33

Cystic Fibrosis

Answer 33

- infertility in males due to abscence of vas deferens and therefore absent sperm. - Tx of CF = N-acetylcysteine, dornase alfa

Question 34

Duchenne MD

Answer 34

- Frameshift mutation | - Dilated cardiomyopathy = common cause of death.

Question 35

Becker MD

Answer 35

-X-linked point mutation

Question 36

Myotonic type 1 MD

Answer 36

- CTG trinuc. repeat in DMPK gene. - abnormal expression of myotonin protein kinase. - frontal balding, testicular atrophy, arrythmia.

Question 37

Fragile X | -whats the trinuc?

Answer 37

CGG

Question 38

Down's Syndrome

Answer 38

-Brushfield spots, gap btwn first 2 toes, hirschsprungs. -meiotic nondisjunction, robertsonian translocation, mosaicism. -First-trimester ultrasound commonly shows:  nuchal translucency and hypoplastic nasal bone; dec. PAPP-A, inc. b-hCG. -Second-trimester quad screen shows:  dec. α-fetoprotein, inc. b-hCG,  dec. estriol, inc.  inhibin A.

Question 39

Edwards syndrome

Answer 39

- micrognathia, low set ears, congenital heart disease, clenched hands, - PAPP-A and b-HCG = both dec in 1st trimester. - Quad screen: everything dec. (AFP, B-hCG, estriol, inhibin A).

Question 40

Patau syndrome

Answer 40

- microphthalmia, microcephaly, cleft lip/palate, holoprosencephaly, polydactyly, congenital heart disease. - dec. b-hcg & PAPP-A. - inc. nuchal translucency.

Question 41

Cri-du-chat syndrome

Answer 41

-5p microdeletion -microcephaly, intellectual disability, high-pitched crying/mewing, epicanthal folds, cardiac abnormalities (VSD).

Question 42

Williams syndrome

Answer 42

- 7q microdeletion (incl. elastin gene). - “elfin” facies, intellectual disability, hypercalcemia ( sensitivity to vitamin D), well-developed verbal skills, extreme friendliness with strangers, cardiovascular problems.

Question 43

Vitamin A

Answer 43

treates measles & AML-M3

Question 44

B2 deficiency

Answer 44

Cheilosis, Corneal vascularization.

Question 45

Vitamin C: uses

Answer 45

- Reduces ferric to ferrous - hydroxylation of lysine & proline - dopamine => NE

Question 46

Vitamin E

Answer 46

-can enhance anti-coag effects of warfarin. May lead to bleeding problems.

Question 47

hyPOphosphorylated Rb

Answer 47

- No passage from G1 to S. - Cell stopped. - Abnormal cell.

Question 48

hyPERphosphorylatd Rb

Answer 48

- inactive - Cell can progress - everything is normal