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39 Cards in this Set
- Front
- Back
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What unit is responsible for RNA primase removal in prokaryotes?
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DNA Pol I
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What unit removes positive supercoils ahead of the DNA replication fork?
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DNA Topo II
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What is xeroderma pigmentosum?
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- Defective excisition repair
- Related to thymidine dimers - Associated w/ UV exposure - Associated w/ melanoma |
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List two unique characteristics of RNA pol.
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1. no proofreading function
2. no primer needed -- can initiate chains |
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What inhibits RNA pol II?
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alpha-amanitin
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What enzyme is responsible for attaching the appropriate aa to a tRNA?
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aminoacyl-tRNA synthetase
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List the important parts of de novo purine synthesis.
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Ribose-5-phosphate (from HMP shunt) --PRPP synthetase--> PRPP --PRPP amidotransferase--> ...IMP --> AMP and GMP
(AMP, IMP, and GMP would inhibit de novo purine synthesis) |
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List important components of de novo pyrimadine synthesis.
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- CO2 + glutamine + ATP initiate
- PRPP is necessary - Thymidylate synthase is necessary Dihydrofolate reductase (DHFR) is important - THF is in there somewhere |
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List important components of each of the 2 purine salvage pathways.
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GMP <--> Guanine: important enzyme is HGPRT
AMP --> adenosine --adenosine deaminase--> inosine --> hypoxanthine --> xanthine --xanthine oxidase--> uric acid hypoxanthine --HGPRT--> IMP --> AMP |
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What is adenosine deaminase deficiency?
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- SCID
- infections in young children - no B- or T- cell function |
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What is Lesch-Nyhan syndrome?
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- HGPRT deficiency
- mental retardation (mild) - self mutilation - hyperuricemia (excess uric acid) |
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What is allopurinol?
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- Tx of gout
- inhibits PRPP amidotransferase - inhibits xanthine oxidase |
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What is 6-mercaptopurine?
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- Antineoplastic
- inhibits PRPP amidotransferase |
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What is methotrexate?
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- antineoplastic
- DHFR inhibitor |
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What is hydroxyurea?
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- antineoplastic
- inhibits ribonucleotide reductase - Tx sickle cell anemia |
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What is a pyrimidine analog that stops chain elongation and serves as an antineoplastic?
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cytosine arabinoside
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What is polycistronic?
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A single prokaryotic mRNA transcript can encode several genes w/ no RNA processing
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Describe transcription termination in prokaryotes.
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Stemp loop (GC rich) and UUUU or stem loop and rho factor
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Discuss initiation of translation in prokaryotes / eukaryotes.
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Prokaryotes: 30S subunit (other is 50S) binds to Shine-Delgarno sequence
Eukaryotes: 40S (other is 60S) associates w/ 5' cap |
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What are tetracyclines?
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Prevent binding of aminoacyl-tRNA to ribosome
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What is linezolid?
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Blocks formation of translation initiation complex
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What are aminoglycosides?
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cause misreading at initiation
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What are macrolides?
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interfere w/ translocation
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What is clindamycin?
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interferes w/ translocation
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What is cholramphenicol?
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inhibits ribosomal peptidyl transferase
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What proteins are translated on RER ribosomes?
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- secreted, membrane-bound, lysozomal
- they have an N-terminal hydrophobic sequence |
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Discuss mannose phosphorylation.
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- takes place in golgi
- phosphate addition to mannose - post-translational protein modification - targets protein for lysosome |
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What is I-cell disease?
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- defect in mannose phosphorylation
- leads to lysosomal enzyme release into extracellular space |
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Regarding collagen, what is required for the hydorxylation of proline and lysine?
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Vitamin C
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What is scurvy?
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reduced hydroxylation / collagen formation due to Vit C deficiency
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What causes osteogenesis imperfecta?
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collagen gene mutations
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What causes Ehlers-Danlos Syndrome?
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- collagen and lysine hydroxylase gene mutations
- hyperextensible, fragile skin w/ hypermobile joints and bruising (ecchymoses) |
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What is Menkes disease?
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- Deficient collagen cross linking secondary to copper deficiency
- Causes depigmented hair, arterial tortuosity, cerebral degeneration, osteoporosis |
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What cells are rich in RER?
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- mucus secreting goblet cells of the small intestine
- antibody secreting plasma cells |
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What cells are rich in SER?
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- liver hepatocytes
- steroid-producing cells of the adrenal cortex |
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What are the functions of the golgi?
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1. distribution center
2. modfies N-oligosaccs on asparagine 3. Adds O-oligosaccs to serine and threonine 4. Proteoglycan assembly 5. Sulfation of sugars 6. Addition of mannose-6-phosphate |
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What is Chediak-Higashi syndrome?
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Defect in microtubule polymerization, leading to decreased phagocytosis
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Discuss the structure of cilia.
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- 9+2 arrangement
- dynein (ATPase) for retrograde sliding of doublets - kinesin for anterograde |
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What is the function of phosphatidylcholine (lecithin)?
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- major component of: RBCs, myelin, bile, surfactant
- esterification of cholesterol |
