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139 Cards in this Set

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  • Back
fatty acid oxidation (beta-oxidation), acteyl-CoA production, Krebs cycle occur where?
glycolysis, fatty acid synthesis, HMP shunt, protein synthesis (RER), steroid syntheis (SER) occur where?
where do gluconeogenesis, urea cycle, and heme synthesis occur?
both mitochondria and cytoplasm
the 2 phosphoanhydride bonds in ATP have how many kcal/mol each?
7 kcal/mole
aerobic metabolism of glucose produces how many ATP via malate shuttle?
38 (malate - mal8)
aerobic metabolism of glucose produces how many ATP via G3P shuttle?
how many ATP per glucose does anaerobic glycolysis produce?
what is ATP composed of?
base (adenine), ribose, 3 phosphoryls, 2 phosphoanhydride bonds
ATP + methionine = ?
S-adenosyl-methionine (SAM)
what does S-adenosyl-methionine do?
transfers methyl units to a wide variety of acceptors (SAM the methyl donor man)
regeneration of methionine (and thus SAM) is dependent on what?
vitamin B12
this yields CAMP via adenylate cyclase
this yields cGMP via guanylate cyclase
what is the intermediate between glutamate and GABA? what does it require?
glutamate decarboxylase - requires vitamin B6
choline -> ACh via what?
choline acetyltransferase
arachidonate yields what products via cyclooxygenase/lipoxygenase?
prostaglandins, thromboxanes, leukotrienes
what is the rate-limiting enzyme of glycolysis?
phosphofructokinase (PFK)
phosphofructokinase catalyzes fructose-6-P to what?
what reaction does bisphosphoglycerate mutase catalyze?
1,3-BPG to 2,3 BPG
what is NADPH used in?
1. anabolic processes
2. respiratory burst
3. P-450
this is usually used in catabolic processes to carry reducing equivalents away as NADH
this is used in anabolic processes (steroid and fatty acid synthesis) as a supply of reducing equivalents
NADPH - product of the HMP shunt
where is hexokinase found?
throughout the body
where is glucokinase found?
primarily in the liver (gLucokinase-Liver)
this enzyme phosphorylates excess glucose to sequester it in the liver as G6P
what enzyme is feedback inhibited by G6P?
how do RBCS metabolize glucose? what do they depend on?
anaerobically (no mitochondria) - therefore depend solely on glycolysis
what catalyzes D-glucose -> G-6-P?
what catalyzes fructose-6-P -> fructose 1,6-BP?
phoshofructokinase (rate-limiting step)
what inhibits fructose-6-P -> fructose 1,6-BP?
ATP, citrate
what promotes fructose-6-P -> fructose 1,6-BP?
AMP, frucotse-2,6-BP
what catalyzes phosphoenolpyruvate -> pyruvate?
pyruvate kinase
what inhibits phosphoenolpyruvate -> pyruvate?
ATP, alanine
what promotes phosphoenolpyruvate -> pyruvate?
what catalyzes pyruvate -> acetyl-CoA?
pyruvate dehydrogenase
what inhibits pyruvate -> acetyl-CoA?
ATP, NADH, acetyl-CoA
chronic granulomatous disease is related to a deficiency of what?
NADPH oxidase
deficiencies in hexokinase, glucose phosphate isomerase, aldolase, triosephosphate isomerase, phosphate glycerate kinase, enolase, and pyruvate kinase are associated with what?
hemolytic anemia
what does the pyruvate dehydrogenase complex require?
first 4 B vitamins plus lipoic acid:
1. pyrophosphate (B1, thiamine; TPP)
2. FAD (B2, riboflavin)
3. NAD (B3, niacin)
4. CoA (B5, panthothenate)
5. lipioic acid
pyruvate + NAD+ + CoA -> ???
acetyl-CoA + CO2 + NADH
what happens in pyruvate dehydrogenase deficiency?
causes backup of substrate (pyruvate and alanine), resulting in lactic acidosis - neuro defects
what is the treatment for pyruvate dehydrogenase deficiency?
increase intake of ketogenic nutrients, e.g. high fat content or increased lysine and leucine
what are the only purely ketogenic amino acids?
lysine and leucine
B1 deficiency in alcoholics can lead to what other deficiency?
pyruvate dehydrogenase
how many ATP equivalents are needed to generate glucose from pyruvate?
what serves as a carrier of amino groups from muscle to liver in pyruvate metabolism?
what does the Cori cycle do?
transfers excess reducing equivalents from RBCs and muscle to liver, allowing muscle to function anaerobically - net 2 ATP
what complex requires the same cofactors as the pyruvate dehydrogenase complex?
alpha-ketoglutarate dehydrogenase complex
how many ATP/acetyl-CoA does the TCA cycle produce?
how many NADH per acetyl CoA does the TCA cycle produce? per glucose?
3, 6
how many FADH2 and GTP does the TCA cycle produce per acetyl CoA?
1 of each (2 per glucose)
how many CO2 does the TCA cycle produce per acetyl CoA?
2 (CO2); 4 per glucose
in the electron transport chain, 1 NADH yields what?
in the electron transport chain, 1 FADH2 yields what?
what do rotenone, antimycin A, CN-, CO do?
directly inhibit electron transport, causing a decrease of proton gradient and block of ATP synthesis
what does oligomycin do?
directly inhibits mitochondrial ATPase, causing an increase of proton gradient, but no ATP is produced because electron transport stops
what do uncoupling agents, e.g. 2,4 DNP, do to oxidative phosphorylation?
increase permeability of membrane, causing a decrease of proton gradient and increased O2 consumption; ATP synthesis stops, electron transport continues
what are the irreversible enzymes in gluconeogenesis?
pyruvate carboxylase, PEP carboxykinase, fructose-1,6-bisphosphatase, glucose-6-phosphatase
(Pathway Produces Fresh Glucose)
what does pyruvate carboxylase catalyze? where does it occur?
pyruvate -> oxaloacetate; in mitochondira
this step of gluconeogenesis requires biotin and ATP, and is activated by acetyl-CoA
pyruvate -> oxaloacetate
what catalyzes oxaloacetate -> phophoenolpyruvate? where does this step of gluconeogenesis occur?
PEP carboxykinase; cytosol
what catalyzes fructose 1,6-bisphophate -> fructose-6-P? where does it occur?
fructose-1,6-bisphosphatase; cytosol
what reaction does glucose-6-phosphatase catalyze?
glucose-6-P -> glucose (in cytosol)
where are the enzymes of gluconeogenesis found?
liver, kidneys, intestinal epithelium (muscle cannot participate in gluconeogenesis)
what do deficiencies of the key gluconeogenesis enzymes cause?
what is the role of the pentose phosphate pathway (HMP shunt)?
produces ribose-5-P from G6P for nucleotide synthesis
produces NADPH from NADP+ for fatty acid and steroid biosynthesis and for maintaining reduced glutathione inside RBCs
all reactions of the HMP shunt occur where?
how much ATP is used and produced in the HMP shunt?
in what sites does the HMP shunt occur?
lactating mammary glands, liver, adrenal cortex - all sites of fatty acid or steroid synthesis
what are the ketogenic essential amino acids?
leucine, lysine
what are the glucogenic/ketogenic essential amino acids?
Ile, Phe, Trp
what are the glucogenic essential amino acids?
Met, Thr, Val, Arg, His
which amino acids are required during periods of growth?
Arg, His
what is the most basic amino acid?
arginine and lysine are found in high amounts where?
histones, which bind to negatively charged DNA
at body pH (7.4), acidic amino acids aspartic acid (Asp) and glutamic acid (Glu) have what charge?
at body pH, basic amino acids Arg and Lys have what charge?
what net charge does basic amino acid histidine have at body pH?
no net charge
what amino acids have an extra NH3 group?
Arg and Lys
what cycle degrades amino acids into amino groups?
urea cycle
the urea cycle accounts for what percent of nitrogen in urine?
where in the body does the urea cycle take place?
where in the cell does carbamoyl phosphate incorporation (in urea cycle) take place?
all steps of the urea cycle except for carbamoyl phosphate incorporation occur where?
histamine is derived from what amino acid?
porphyrin -> heme comes from what amino acid?
creatine, urea, and nitric oxide all come from what amino acid?
GABA is derived from what amino acid?
tyrosine (->thyroxine) -> dopa (->melanin) -> dopamine -> NE -> epi originates from what amino acid?
niacin, serotonin, melatonin all come from what amino acid?
what coenzyme is used by pyruvate dehydrogenase to convert pyruvate to acetyl CoA (in the absence of this, pyruvate accumulates and can be converted by lactate dehydrogenase to lactate, which is spilled in the blood causing lactic acidosis)
waht do exopeptidases do?
can remove amino acids from the amino- or carboxyl-terminus of a protein
what do endopeptidases do?
cut AA bond within a molecule
what is the rate-limiting enzyme of glycolysis?
what are the essential amino acids?
lysine, isoleucine, leucine, threonine, valine, tryptophan, phenylaline, methionine, histidine (& tyrosine b/c synthesized from phenylaline; arginine required for growth)
what areas of the body don't need insulin for glucose uptake into cells?
brain, RBCs, intestine, cornea, kidney, liver
where are GLUT2 receptors found?
beta cells
where are GLUT4 receptors found?
muscle and fat
what are the anabolic effects of insulin?
increases glucose transport
increases glycogen synthesis and storage
increases triglyceride synthesis and storage
increases Na retention in kidneys
increases protein synthesis
what does glucagon do to glycogen synthase and phosphorylase?
glucagon phosphorylates stuff -
turns glycogen synthase OFF and phosphorylase ON
what does insulin do to glycogen synthase and phosphorylase?
insulin dephosphorylates stuff -
turns glycogen synthase ON and phosphorylase OFF
where does fatty acid degradation take place?
where its products will be consumed - in the mitochondrion
urine test for ketones does not detect what?
beta-hydroxybutyrate (favored by high redox state)
what are ketone bodies made from?
what are ketone bodies metabolized into by the brain?
2 molecules of acetyl-CoA
what catalyzes the rate-limiting step in cholesterol synthesis?
HMG-CoA reductase, which converts HMG CoA to mevalonate
2/3 of plasma cholesterol is esterified by what?
lecithin-cholesterol acyltransferase (LCAT)
what is the role of pancreatic lipase?
degradation of dietary TG in the small intestine
what degrades TG in circulating chylomicrons and VLDLs?
lipoprotein lipase
what is the role of hepatic TG lipase?
degradation of TG remaining in IDL
what degrades TG in stored adipocytes?
hormone-sensitive lipase
what is the role of alipoprotein A-I?
Activates LCAT (A-activate)
which apolipoprotein binds to the LDL receptor?
apo B-100
what is the role of apo C-II
cofactor for lipoprotein lipase
what apolipoprotein mediates extra (remnant) uptake?
apo E (E-extra)
this lipoprotein delivers dietary triglycerides to peripheral tissues and cholesterol to the liver; secreted by intestinal epithelial cells
excess of this lipoprotein causes pancreatitis, lipemia retinalis, and eruptive xanthomas
what apolipoprotein mediates secretion of chylomicrons?
apo B-48
what lipoprotein delivers hepatic triglycerides to peripheral tissues? what is it secreted by?
VLDL - secreted by liver
this lipoprotein is formed in the degradation of VLDL & delivers TG and cholesterol to the liver, where they are degraded to LDL
what is the role of LDL?
delivers hepatic cholesterol to peripheral tissues
what lipoprotein is formed by lipoprotein lipase modification of VLDL in the peripheral tissue?
excess of this lipoprotein causes atherosclerosis, xanthomas, and arcus corneae
what is the role of HDL?
mediates transport of cholesterol from periphery to liver; acts as a repository for apoC and apoE
from where is HDL secreted?
both liver and intestine
what is the first step in heme synthesis? what catalyzes it?
succinyl CoA + glycine
ALA synthetase
what occurs in lead poisoning?
inhibition of ferrochelatase and ALA dehydrase
what accumulates in urine in lead poisoning?
coproporphyrin and ALA
what is deficient in acute intermittent porphyria?
deficiency in uroporphyrinogen I synthetase
what accumulates in acute intermittent porphyria?
porphobilinogen and delta-ALA
what is the deficiency in porphyria cutanea tarda?
uroporphyrinogen decarboxylase
waht accumulates in urine in porphyria cutanea tarda? what else is this associated with?
uroporphyrin accumulates (tea-colored urine); associated with photosensitivity
painful abdomen, pink urine, polyneuropathy, psych disturbances, precipitated by drugs?
symptoms of porphyrias
which form of hemoglobin has a higher affinity for O2?
relaxed form (300x affinity of taut form)
increased Cl-, H+, CO2, 2,3-BPG and temp favor what form of Hb? Which way does the O2 curve shift?
R form; shifts to right, leading to increased O2 unloading
this is an oxidized form of Hb (ferric, Fe3+) that does not bind O2 as readily but has an increased affinity for CN-
what do you administer in cyanide poisoning?
nitrates to oxidize Hb to methemoglobin form
with what do you treat toxic levels of methemoglobin?
methylene blue
CO2 binding to Hb favors what form?
T (taut)