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139 Cards in this Set
- Front
- Back
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fatty acid oxidation (beta-oxidation), acteyl-CoA production, Krebs cycle occur where?
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mitochondria
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glycolysis, fatty acid synthesis, HMP shunt, protein synthesis (RER), steroid syntheis (SER) occur where?
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cytoplasm
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where do gluconeogenesis, urea cycle, and heme synthesis occur?
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both mitochondria and cytoplasm
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the 2 phosphoanhydride bonds in ATP have how many kcal/mol each?
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7 kcal/mole
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aerobic metabolism of glucose produces how many ATP via malate shuttle?
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38 (malate - mal8)
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aerobic metabolism of glucose produces how many ATP via G3P shuttle?
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36
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how many ATP per glucose does anaerobic glycolysis produce?
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2
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what is ATP composed of?
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base (adenine), ribose, 3 phosphoryls, 2 phosphoanhydride bonds
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ATP + methionine = ?
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S-adenosyl-methionine (SAM)
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what does S-adenosyl-methionine do?
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transfers methyl units to a wide variety of acceptors (SAM the methyl donor man)
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regeneration of methionine (and thus SAM) is dependent on what?
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vitamin B12
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this yields CAMP via adenylate cyclase
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ATP
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this yields cGMP via guanylate cyclase
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GTP
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what is the intermediate between glutamate and GABA? what does it require?
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glutamate decarboxylase - requires vitamin B6
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choline -> ACh via what?
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choline acetyltransferase
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arachidonate yields what products via cyclooxygenase/lipoxygenase?
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prostaglandins, thromboxanes, leukotrienes
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what is the rate-limiting enzyme of glycolysis?
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phosphofructokinase (PFK)
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phosphofructokinase catalyzes fructose-6-P to what?
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fructose-1,6-bis-P
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what reaction does bisphosphoglycerate mutase catalyze?
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1,3-BPG to 2,3 BPG
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what is NADPH used in?
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1. anabolic processes
2. respiratory burst 3. P-450 |
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this is usually used in catabolic processes to carry reducing equivalents away as NADH
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NAD+
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this is used in anabolic processes (steroid and fatty acid synthesis) as a supply of reducing equivalents
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NADPH - product of the HMP shunt
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where is hexokinase found?
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throughout the body
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where is glucokinase found?
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primarily in the liver (gLucokinase-Liver)
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this enzyme phosphorylates excess glucose to sequester it in the liver as G6P
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glucokinase
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what enzyme is feedback inhibited by G6P?
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hexokinase
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how do RBCS metabolize glucose? what do they depend on?
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anaerobically (no mitochondria) - therefore depend solely on glycolysis
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what catalyzes D-glucose -> G-6-P?
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hexokinase/glucokinase
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what catalyzes fructose-6-P -> fructose 1,6-BP?
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phoshofructokinase (rate-limiting step)
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what inhibits fructose-6-P -> fructose 1,6-BP?
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ATP, citrate
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what promotes fructose-6-P -> fructose 1,6-BP?
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AMP, frucotse-2,6-BP
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what catalyzes phosphoenolpyruvate -> pyruvate?
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pyruvate kinase
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what inhibits phosphoenolpyruvate -> pyruvate?
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ATP, alanine
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what promotes phosphoenolpyruvate -> pyruvate?
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fructose-1-6-BP
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what catalyzes pyruvate -> acetyl-CoA?
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pyruvate dehydrogenase
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what inhibits pyruvate -> acetyl-CoA?
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ATP, NADH, acetyl-CoA
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chronic granulomatous disease is related to a deficiency of what?
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NADPH oxidase
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deficiencies in hexokinase, glucose phosphate isomerase, aldolase, triosephosphate isomerase, phosphate glycerate kinase, enolase, and pyruvate kinase are associated with what?
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hemolytic anemia
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what does the pyruvate dehydrogenase complex require?
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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 |
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pyruvate + NAD+ + CoA -> ???
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acetyl-CoA + CO2 + NADH
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what happens in pyruvate dehydrogenase deficiency?
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causes backup of substrate (pyruvate and alanine), resulting in lactic acidosis - neuro defects
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what is the treatment for pyruvate dehydrogenase deficiency?
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increase intake of ketogenic nutrients, e.g. high fat content or increased lysine and leucine
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what are the only purely ketogenic amino acids?
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lysine and leucine
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B1 deficiency in alcoholics can lead to what other deficiency?
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pyruvate dehydrogenase
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how many ATP equivalents are needed to generate glucose from pyruvate?
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6 ATP
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what serves as a carrier of amino groups from muscle to liver in pyruvate metabolism?
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alanine
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what does the Cori cycle do?
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transfers excess reducing equivalents from RBCs and muscle to liver, allowing muscle to function anaerobically - net 2 ATP
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what complex requires the same cofactors as the pyruvate dehydrogenase complex?
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alpha-ketoglutarate dehydrogenase complex
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how many ATP/acetyl-CoA does the TCA cycle produce?
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12
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how many NADH per acetyl CoA does the TCA cycle produce? per glucose?
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3, 6
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how many FADH2 and GTP does the TCA cycle produce per acetyl CoA?
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1 of each (2 per glucose)
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how many CO2 does the TCA cycle produce per acetyl CoA?
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2 (CO2); 4 per glucose
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in the electron transport chain, 1 NADH yields what?
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3 ATP
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in the electron transport chain, 1 FADH2 yields what?
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2 ATP
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what do rotenone, antimycin A, CN-, CO do?
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directly inhibit electron transport, causing a decrease of proton gradient and block of ATP synthesis
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what does oligomycin do?
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directly inhibits mitochondrial ATPase, causing an increase of proton gradient, but no ATP is produced because electron transport stops
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what do uncoupling agents, e.g. 2,4 DNP, do to oxidative phosphorylation?
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increase permeability of membrane, causing a decrease of proton gradient and increased O2 consumption; ATP synthesis stops, electron transport continues
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what are the irreversible enzymes in gluconeogenesis?
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pyruvate carboxylase, PEP carboxykinase, fructose-1,6-bisphosphatase, glucose-6-phosphatase
(Pathway Produces Fresh Glucose) |
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what does pyruvate carboxylase catalyze? where does it occur?
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pyruvate -> oxaloacetate; in mitochondira
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this step of gluconeogenesis requires biotin and ATP, and is activated by acetyl-CoA
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pyruvate -> oxaloacetate
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what catalyzes oxaloacetate -> phophoenolpyruvate? where does this step of gluconeogenesis occur?
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PEP carboxykinase; cytosol
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what catalyzes fructose 1,6-bisphophate -> fructose-6-P? where does it occur?
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fructose-1,6-bisphosphatase; cytosol
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what reaction does glucose-6-phosphatase catalyze?
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glucose-6-P -> glucose (in cytosol)
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where are the enzymes of gluconeogenesis found?
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liver, kidneys, intestinal epithelium (muscle cannot participate in gluconeogenesis)
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what do deficiencies of the key gluconeogenesis enzymes cause?
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hypoglycemia
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what is the role of the pentose phosphate pathway (HMP shunt)?
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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 |
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all reactions of the HMP shunt occur where?
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cytoplasm
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how much ATP is used and produced in the HMP shunt?
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none
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in what sites does the HMP shunt occur?
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lactating mammary glands, liver, adrenal cortex - all sites of fatty acid or steroid synthesis
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what are the ketogenic essential amino acids?
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leucine, lysine
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what are the glucogenic/ketogenic essential amino acids?
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Ile, Phe, Trp
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what are the glucogenic essential amino acids?
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Met, Thr, Val, Arg, His
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which amino acids are required during periods of growth?
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Arg, His
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what is the most basic amino acid?
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arginine
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arginine and lysine are found in high amounts where?
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histones, which bind to negatively charged DNA
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at body pH (7.4), acidic amino acids aspartic acid (Asp) and glutamic acid (Glu) have what charge?
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negative
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at body pH, basic amino acids Arg and Lys have what charge?
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positive
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what net charge does basic amino acid histidine have at body pH?
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no net charge
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what amino acids have an extra NH3 group?
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Arg and Lys
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what cycle degrades amino acids into amino groups?
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urea cycle
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the urea cycle accounts for what percent of nitrogen in urine?
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90%
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where in the body does the urea cycle take place?
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liver
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where in the cell does carbamoyl phosphate incorporation (in urea cycle) take place?
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mitochondria
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all steps of the urea cycle except for carbamoyl phosphate incorporation occur where?
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cytosol
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histamine is derived from what amino acid?
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histidine
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porphyrin -> heme comes from what amino acid?
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glycine
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creatine, urea, and nitric oxide all come from what amino acid?
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arginine
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GABA is derived from what amino acid?
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glutamate
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tyrosine (->thyroxine) -> dopa (->melanin) -> dopamine -> NE -> epi originates from what amino acid?
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phenylaline
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niacin, serotonin, melatonin all come from what amino acid?
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tryptophan
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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)
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thiamine
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waht do exopeptidases do?
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can remove amino acids from the amino- or carboxyl-terminus of a protein
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what do endopeptidases do?
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cut AA bond within a molecule
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what is the rate-limiting enzyme of glycolysis?
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phosphofructokinase
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what are the essential amino acids?
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lysine, isoleucine, leucine, threonine, valine, tryptophan, phenylaline, methionine, histidine (& tyrosine b/c synthesized from phenylaline; arginine required for growth)
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what areas of the body don't need insulin for glucose uptake into cells?
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brain, RBCs, intestine, cornea, kidney, liver
BRICK L |
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where are GLUT2 receptors found?
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beta cells
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where are GLUT4 receptors found?
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muscle and fat
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what are the anabolic effects of insulin?
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increases glucose transport
increases glycogen synthesis and storage increases triglyceride synthesis and storage increases Na retention in kidneys increases protein synthesis |
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what does glucagon do to glycogen synthase and phosphorylase?
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glucagon phosphorylates stuff -
turns glycogen synthase OFF and phosphorylase ON |
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what does insulin do to glycogen synthase and phosphorylase?
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insulin dephosphorylates stuff -
turns glycogen synthase ON and phosphorylase OFF |
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where does fatty acid degradation take place?
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where its products will be consumed - in the mitochondrion
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urine test for ketones does not detect what?
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beta-hydroxybutyrate (favored by high redox state)
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what are ketone bodies made from?
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HMG-CoA
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what are ketone bodies metabolized into by the brain?
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2 molecules of acetyl-CoA
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what catalyzes the rate-limiting step in cholesterol synthesis?
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HMG-CoA reductase, which converts HMG CoA to mevalonate
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2/3 of plasma cholesterol is esterified by what?
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lecithin-cholesterol acyltransferase (LCAT)
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what is the role of pancreatic lipase?
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degradation of dietary TG in the small intestine
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what degrades TG in circulating chylomicrons and VLDLs?
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lipoprotein lipase
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what is the role of hepatic TG lipase?
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degradation of TG remaining in IDL
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what degrades TG in stored adipocytes?
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hormone-sensitive lipase
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what is the role of alipoprotein A-I?
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Activates LCAT (A-activate)
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which apolipoprotein binds to the LDL receptor?
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apo B-100
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what is the role of apo C-II
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cofactor for lipoprotein lipase
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what apolipoprotein mediates extra (remnant) uptake?
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apo E (E-extra)
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this lipoprotein delivers dietary triglycerides to peripheral tissues and cholesterol to the liver; secreted by intestinal epithelial cells
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chylomicron
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excess of this lipoprotein causes pancreatitis, lipemia retinalis, and eruptive xanthomas
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chylomicron
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what apolipoprotein mediates secretion of chylomicrons?
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apo B-48
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what lipoprotein delivers hepatic triglycerides to peripheral tissues? what is it secreted by?
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VLDL - secreted by liver
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this lipoprotein is formed in the degradation of VLDL & delivers TG and cholesterol to the liver, where they are degraded to LDL
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IDL
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what is the role of LDL?
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delivers hepatic cholesterol to peripheral tissues
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what lipoprotein is formed by lipoprotein lipase modification of VLDL in the peripheral tissue?
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LDL
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excess of this lipoprotein causes atherosclerosis, xanthomas, and arcus corneae
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LDL
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what is the role of HDL?
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mediates transport of cholesterol from periphery to liver; acts as a repository for apoC and apoE
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from where is HDL secreted?
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both liver and intestine
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what is the first step in heme synthesis? what catalyzes it?
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succinyl CoA + glycine
ALA synthetase |
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what occurs in lead poisoning?
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inhibition of ferrochelatase and ALA dehydrase
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what accumulates in urine in lead poisoning?
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coproporphyrin and ALA
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what is deficient in acute intermittent porphyria?
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deficiency in uroporphyrinogen I synthetase
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what accumulates in acute intermittent porphyria?
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porphobilinogen and delta-ALA
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what is the deficiency in porphyria cutanea tarda?
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uroporphyrinogen decarboxylase
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waht accumulates in urine in porphyria cutanea tarda? what else is this associated with?
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uroporphyrin accumulates (tea-colored urine); associated with photosensitivity
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painful abdomen, pink urine, polyneuropathy, psych disturbances, precipitated by drugs?
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symptoms of porphyrias
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which form of hemoglobin has a higher affinity for O2?
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relaxed form (300x affinity of taut form)
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increased Cl-, H+, CO2, 2,3-BPG and temp favor what form of Hb? Which way does the O2 curve shift?
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R form; shifts to right, leading to increased O2 unloading
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this is an oxidized form of Hb (ferric, Fe3+) that does not bind O2 as readily but has an increased affinity for CN-
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methemoglobin
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what do you administer in cyanide poisoning?
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nitrates to oxidize Hb to methemoglobin form
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with what do you treat toxic levels of methemoglobin?
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methylene blue
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CO2 binding to Hb favors what form?
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T (taut)
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