Biochem Flashcards
α-amanitin
- found in death cap mushroom.
- inhibits RNA pol 2 (makes mRNA).
- hepatotoxic.
P-bodies
- mRNA quality control.
- cytoplasmic.
- contain exonucleases, decapping enzymes, and microRNAs
- mRNAs may be stored here for future translation.
spliceosomal snRNPs
- Abs against these = anti-smith Abs
- specific for SLE
Trimming
- post-translational modification.
- Removal of N- or C-terminal propeptides from zymogen to generate mature protein (e.g., trypsinogen to trypsin).
Ingredients to make Niacin (B3)
Tryptophan
B2 (riboflavin)
B6 (pyridoxine)
Base excision repair
1-glycosylase = strips off base 2-endonuclease = cleaves 5' end 3-lyase = cleaves 3' end 4-DNA pol 5-ligase
Enhancers and silencers (of gene expression)
Variable locations
COP1
Retrograde
- Golgi => Golgi
- Golgi => ER
COP2
Anterograde
- Golgi => Golgi
- ER => Golgi
Ribozyme (rRNA)
Catalyzes peptide bond formation btwn amino acids
Ouabain
Inhibits Na/K ATPase by binding to K site.
Type 3 Cartilage
Reticulin:
- blood vessels
- uterus
- fetal tissue
- granulation tissue
Problems forming triple helix in RER (collagen).
Osteogenesis imperfecta
Problems cross-linking collagen (lysyl oxidase)
Ehlers Danlos
Menkes Disease
- CT disease
- impaired copper absorption and transport.
- leads to dec. lysyl oxidase activity (cross links collagen)
- brittle, “kinky” hair, growth retardation and hypotonia.
Pleiotropy
One gene contributes to multiple phenotypic effects.
ie. PKU
Dominant negative mutation
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.
McCune-Albright syndrome
-lethal if themutation is somatic, but survivable if mosaic.
-polyostotic fibrous dysplasia with cafe-au-lait skin
pigmentation and endocrinopathies.
Locus heterogeneity
Mutations at different loci can produce a similar
phenotype.
-ie. albinism
Allelic heterogeneity
Different mutations in the same locus produce the same phenotype.
-ie. beta-thal
Heteroplasmy
Presence of both normal and mutated mtDNA, resulting in variable expression in mitochondrial inherited disease.
Heterodisomy
meiosis 1 error
Isodisomy
meiosis 2 error
Prader-Willi & angelman
-which chromosome?
15
-or uniparental disomy. Inherit two methylated copies.
Hypophosphatemic rickets
Formerly known as vitamin D–resistant rickets. Inherited disorder resulting in phosphate wasting at proximal
tubule. Results in rickets-like presentation.
Mitochondrial myopathies
rare disorders; often present with myopathy, lactic acidosis and CNS disease. 2° to failure in oxidative
phosphorylation. Muscle biopsy often shows “ragged red fibers.”
FAP
-which chromosome?
5
-5 letters in “polyp”.
Osler-Weber-Rendu Syndrome
aka Hereditary hemorrhagic telangiectasia
- Inherited disorder of blood vessels.
- Findings: telangiectasia, recurrent epistaxis, skin discolorations, arteriovenous malformations (AVMs), GI bleeding, hematuria.
NF1
-which chrom?
17
-17 letters in “von Recklinghausen.”
NF2
-which chrom?
22
-NF2 = 22
VHL
-which chrom?
3
-VHL = 3 letters
Hardy Weinberg
The frequency of an X-linked recessive disease
in males = q and in females = q^2.
Cystic Fibrosis
- infertility in males due to abscence of vas deferens and therefore absent sperm.
- Tx of CF = N-acetylcysteine, dornase alfa
Duchenne MD
- Frameshift mutation
- Dilated cardiomyopathy = common cause of death.
Becker MD
-X-linked point mutation
Myotonic type 1 MD
- CTG trinuc. repeat in DMPK gene.
- abnormal expression of myotonin protein kinase.
- frontal balding, testicular atrophy, arrythmia.
Fragile X
-whats the trinuc?
CGG
Down’s Syndrome
-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.
Edwards syndrome
- 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).
Patau syndrome
- microphthalmia, microcephaly, cleft lip/palate, holoprosencephaly, polydactyly, congenital heart disease.
- dec. b-hcg & PAPP-A.
- inc. nuchal translucency.
Cri-du-chat syndrome
-5p microdeletion
-microcephaly, intellectual disability, high-pitched
crying/mewing, epicanthal folds, cardiac abnormalities (VSD).
Williams syndrome
- 7q microdeletion (incl. elastin gene).
- “elfin” facies, intellectual disability, hypercalcemia (sensitivity to vitamin D), well-developed verbal skills, extreme friendliness with strangers, cardiovascular problems.
Vitamin A
treates measles & AML-M3
B2 deficiency
Cheilosis, Corneal vascularization.
Vitamin C: uses
- Reduces ferric to ferrous
- hydroxylation of lysine & proline
- dopamine => NE
Vitamin E
-can enhance anti-coag effects of warfarin. May lead to bleeding problems.
hyPOphosphorylated Rb
- No passage from G1 to S.
- Cell stopped.
- Abnormal cell.
hyPERphosphorylatd Rb
- inactive
- Cell can progress
- everything is normal
