Biochemistry (FA) Flashcards
Pyruvate Carboxylase – substrate, product, cofactors, location
- Mitochondria
- Pyruvate to Oxaloacetate
- requires Biotin, ATP, activated by acetyl CoA
(Gluconeogenesis)
PEP Carboxykinase – location, substrate, product, cofactors
- Cytosol
- Oxaloacetate to PEP
- requires GTP
(Gluconeogenesis)
Fructose 1,6-bisphosphatase - location, substrate, product, cofactors
- Cytosol
- Fructose 1,6-bisphosphate to Fructose-6-P
Glucose-6-phosphatase – location, substrate, product, cofactors
- ER
- G-6-P to Glucose
(Gluconeogenesis – liver)
Apolipoprotein E - function?
Mediates remnant uptake
seen on all
Apolipoprotein A-I - function?
Activates LCAT
seen on VLDL & HDL
Apolipoprotein C-II - function?
Lipoprotein lipase cofactor
seen on Chylomicrons, VLDL, & HDLs
Apolipoprotein B-48 - function?
Mediates chylomicron secretion
seen on Chylomicrons & Chylomicron remnants
Apolipoprotein B-100 - function?
Binds LDL receptor
seen on VLDL, IDL, & LDL
Lipoprotein Lipase (LPL) function?
Degradation of TG circulating in chylomicrons & VLDLs
Hepatic TG lipase (HL) function?
Degradation of TG remaining in IGL
Hormone-sensitive lipase function?
Degradation of TG stored in adipocytes
Lecithin-cholesterol Acyltransferase (LCAT) function?
Catalyzes esterification of cholesterol.
LCAT is bound to plasma HDL and LDL. As it esterifies cholesterol in HDL, it allows HDL to participate in reverse cholesterol transport.
Esterification makes the cholesterol more hydrophobic → sequestered in the core of the lipoprotein.
CETP (cholesteryl ester transfer protein) function?
Facilitates the transfer of cholesteryl ester (added by LCAT) from HDL to VLDL, IDL, and LDL in exchange for triacylglycerol.
ACAT (acylcoenzyme A: cholesterol acyltransferase) function?
ACAT (acylcoenzyme A: cholesterol acyltransferase) esterifies cholesterol inside the liver (for storage) and intestine (for transport in chylomicrons).
Free cholesterol in the bloodstream is esterified by LCAT (lecithin-cholesterol acyltransferase)
Familial Type I Hyperchylomicronemia
- inc’d Chylomicrons, TG, Cholesterol
- Autosomal Recessive
- Lipoprotein Lipase deficiency or altered apolipoprotein C-II
- Causes: Pancreatitis, Hepatosplenomegaly, & eruptive/pruritic xanthomas (no inc’d risk for atherosclerosis
Familial Type IIa Hypercholesterolemia
- inc’d LDL & Cholesterol
- Autosomal Dominant
- Absent or dec’d LDL receptors
- Causes: accelerated atherosclerosis, tendon (Achilles) xanthomas, & corneal arcus
Familial Type IV Hypertriglyceridemia
- inc’d VLDL & TG
- Autosomal Dominant
- Hepatic overproduction of VLDL
- Causes pancreatitis
Abetalipoproteinemia
Autosomal recessive mutation in microsomal triglyceride transfer protein (MTP) gene
- dec’d B-48 & B-100
- dec’d Chylomicron & VLDL synthesis & secretion
- Symptoms appear in first few months of life
- Intestinal biopsy shows lipid accumulation w/in enterocytes due to inability to export absorbed lipid as chylomicrons
Findings: Failure to thrive, steatorrhea, acanthocytosis, ataxia, night blindness
______ has 5’ –> 3’ synthesis & proofreads w/ 3’ –> 5’ exonuclease.
DNA Polymerase III
______ is unique in its ability to excise RNA primer w/ 5’ –> 3’ exonuclease.
DNA Polymerase I
also has same other functions as DNA Polymerase III
______ adds DNA to 3’ ends of chromosomes to avoid loss of genetic material w/ every duplication
Telomerase
Nonhomologous end joining brings together 2 ends of DNA fragments to repair double-stranded breaks. This is mutated in what disease?
Ataxia Telangiectasia
Patients w/ _____ make antibodies to spliceosomal snRNPs.
Lupus
α-amanitin, found in Amanita phalloides (death cap mushrooms), inhibits ________. What does this cause if ingested?
Inhibits RNA Polymerase II (makes mRNA)
Causes severe hepatotoxicity if ingested
Young child with fatty diarrhea, failure to thrive (malabsorption), & neurologic manifestations. Labs show decreased cholesterol in blood.
Abetalipoproteinemia
- dec’d synthesis of apolipoprotein B leads to inability to generate chylomicrons, & therefore dec’d secretion of cholesterol & VLDL into bloodstream. Fat accumulates in the enterocytes.
