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Biochem final
final
Question | Answer |
---|---|
Rifampicin | interferes with initiation of transcription by blocking the passage channel fo RNA/DNA hybrid, prok only |
Actinomycin | inserts itself btwn base pairs (DNA can't be a template for RNA pol) both prok and eukaryotes |
streptolydigin | binds to RNA pol, prevents phosphodiester bond formation (prok) |
α-amanitin | strongly inhibits RNA polymerase II, weakly inhibits RNA pol III (euk) |
streptomycin | inhibits initiation, misreading of mRNA (prok) |
tetracycline | binds to 30s, inhibits binding of aminoacyl-tRNA (prok) |
chloramphenicol | inhibits peptidle transferase at 50s (prok) |
cyclohexamide | inhibits peptidyl transferase activity in 60s (euk) |
Erythromycin | binds to 50s subunit and inhibits translocation |
Puromycin | premature chain termination, acts as an analog of aminoacyl-tRNA (prok & euk) |
Cyclin D | CDK 6&4 get through G1 |
Cyclin E | CDK 2 G1--> S |
Cyclin A | S-->G2-->M, regulated by APC |
Cyclin B | CDK1 through M, regulated by APC |
Retinoblastoma | Rb is a tumor suppressor gene, usually binds & inactivates E2F, with growth signals Rb is phosphorylated and releases E2F (transcription factor) |
p53 | transcription factor, ordinarily synthesized and degraded, if it hangs out to long it moves into the nucleus and turns on transcription of p21 (CDK-inhibitor) |
Li_Fraumeni Syndrome | inherited p53 defect |
autosomal dominant | 1. no skipping of generations 2. males and females are equally likely to be affected 3. normal siblings of affected individuals do NOT pass it on 4. usually a structural protein not an enzyme |
Marfan Syndrome | Autosomal dominant (variable expressivity), mutation in the FBN1 gene, chrom 15 - encodes for fibrillin-1, skeletal abnormalities |
Huntington | Autosomal dominance (late onset), CAG repeats in the coding section (encoded bc of strand slippage during replication) |
myotonic dystrophy | autosomal dominant, delayed expression in NON-translated region, slowly progressive muscle weakness and myotonia |
genetic anticipation | tendency for the severity of the disease to increase and the age of onset to decrease |
fragile x | X-linked dominant increased CGG repeats, FMR1 not expressed, no protein made, since females carry 2 Xs tends to be milder |
neurofibromatosis type 1 | cafe au lait spots, protein is neurofibromin which causes a loss of growth supressors, autosomal dominant inheritance (high new mutation rate) |
achondroplasia | autosomal dominant, high recurrent mutation, short stature, mutation in the fibroblast growth factor receptor gene 3 (severely shortened bones) |
Potter's syndrome | autosomal dominant, incomplete penetrance |
Autosomal recessive | 1. equal male & female 2. sibling recurrence rate is 1/4 3. characteristically found in siblings, not parents 4. parents may be related 5. may be an isolated event in small sibships |
X-linked recessive | never pass father to son affected females MUST have affected fathers typically passed from affected grandfather to 1/2 of grandsons |
X-linked dominan | never pass father to son all daughters of affected parents are affected, all sons of affected male and unaffected female are normal affected females x normal male = 1/2 affected sons male more seriously affected than females |
Patau | trisomy 13, usually die within 3 months |
edwards syndrome | trisomy 18, distinct facial features, 80% of those affected are females, |
klinefelter | XXY low levels of testosterone |
turner | XO, underdeveloped female secondary sex characteristics, webbed neck |
williams syndrome | deletion of the q arm of chrom 7 (including elastin gene), broad forehead, short nose, widely spaced teeth |
cri du chat | deletion of the short arm of chrom 5, 80% of time comes from father's sperm,abnormal larynx development = mewing (becomes normal w/i few weeks), |
imprinting | reversible form of inactivation, acts through methylation, only occurs on 9 chrom |
prader-willi | small deletion on the short arm of chrom 15 from father. hypotonia, difficulty feeding, insatiable appetite, small hands and feet, hypogonadism |
angelman | small deletion on short arm of chrom 15 from mother, severe mental retardation, nonverbal, balence disorder |
osteogenesis imperfecta | mosaicism, type 1 collagen disorder, easy fractures of the bone, autosomal dominant |
methotrexate and aminopterin | inhibit thymidylate synthase (no dTTP) |
fluorouracil | inhibits dihydrofolate reductase (do dTTP) |
HGPRT | deficiency --> Lesch Nyan, X-linked recessive |
Adenosine deaminase deficiency | used in purine salvage pathway, causes SCID, ATP and dATP accumulate --> imbalnce of nucleotide pool, prevents DNA syn |
glutamine PRPP amidotransferase | purine synthesis, removes pyrophosphate from PRPP leavind a phosphoribosyl amine |
Xanthylate synthase | uses NAD and H2O to form a carbonyk, can be inhibited by GMP |
allopurinal | suicide inhibitor of xanthine OXIDASE, enzyme can't degrade purines to urate |
carbamoyl phosphate synthase | pyrimidine synthesis, NOT from urea cycle, inhibited by UTP, activated by PRPP |
ribonucleotide reductase | removes 2'OH, so they can be incorporate into DNA, regulated to keep the dNTPs in balence |
campothecin and doxorubicin | type 1&2 topoisomerase inhibitors, stabilize the DNA-topoisomerase complex, DNA makes cut and the drug blocks the reattachment |
cohesins | hold chromosomes together, regulated by APC (through securin and separase) |
T-loops | hides dsDNA from DNA repair machinery, free of nucleosomes, stabilized by TRF1 proteins |
RNA syn | does NOT require a promoter, initiation is TATA region, termination is GC rich (forms hairpin), can also have rho factor (ATPase and a helicase, binds to Crich, G poor region and pulls it away from the RNA pol and DNA template) |
RNA trasncription | a DAB of F brings RNAPOL, EH? |
spliceosom | snRNPs and pre-mRNA |
B-thalassemia | abnormal splicing of B-globin |
amino-acyl tRNA stnthetase | requires ATP |
ran | signal peptide receptor in nucleus and cytoplasm, serves in both nuclear import and export, |
NF-AT | transcription factor mediated by nuclear import/export, wehn it is stimulated calcinurin moves to the nucleus and stimulates trascription, in low calcium environment calcineurin falls off and the NF-AT is kicked out of the cell |
cholera | colonize the small intestine and produce mono-ADP-ribotransferase, modifies the G-protein involved in walter and salt balence. G-protein cannot release GTP so Adenylyl cyclase is active --> inc cAMP --> intestinal cells secrete water and salts |
Pertussis | whooping cough, colonize the lungs and add ADP-ribose ot G-protein resulting in inc mucus secretion |
Diphtheria | infect nasopharynx/skin, toxin is endocytosed after binding to epidermal growth factor receptor --> acidified in endosome --> ribosylation of EF2 (blocks protein syn) |
Ricin | heterodimeric ribosome-inhibiting proteinm doens't use NAD+ instead cleaves A and stops protein syn |
somatic cell hybrids | use sendai virus to fuse 2 cells and nuclei from different species. can't be used for disease genes |
RFLP | markers to certain locations on different chromosomes, can indicate whether crossing-over has occurred btwn the marker and the disease gene (show you how close together the 2 are) |
Beckswith Wiedemann Syndrome | chrom 11 - imprinted in father, maternal deletion = syndrome, paternal deletion = no effect |
CGH comparative genomic hybridization | detects global gains and losses by compaing sa,ple DNA to the normal human chrom, can detect anueploidy or gene amplificaion in tumors, will not detect balenced rearrangements |
GPCRs | largest family of cell surface receptors, 7transmembrane domains, extracellular domain binds ligand, can be inactivated by receptor inactivation, receptor internalization or receptor downregulation |
ATP used per peptide bond in protein synthesis | 4 |
Neurofibromatosis II | mutation on tumor supressor gene, chrom 22, Bilateral acoustic neuroma (CN VIII), Juvenile cateracts |
Rett's | MECP2 genes>> form synapses between nerve cells, unclear, X-linked, fatal in males, hand-wringing |
Beckwith- Wiedemann | Macrosomia: large body Macroglossi: large tongue Enlargement of internal organs maternally imprinted Wilm’s tumor and embryonal tumors omphalocele |
Xeroderma pigmentosa | inability to repair thymine dimers |
Ataxia telangectasia | defect in ATM protein>> protein kinase activated by double strand breaks |
Wilm’s tumor | defect in the imprinting of the insulin like growth factor 2 gene>> both maternal and paternal expression Symptoms: Childhood tumor of the kidney |
karyotyping with light microscopy | G-banding |