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108 Cards in this Set
- Front
- Back
Niacin is a _____ soluble vitamin that is used in the cofactors _____ and _____. What "B" vitamin is it?
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water; NAD+; NADP+. It's B3.
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The common cofactor containing pantothenic acid is ______. The associated deficiency disease is _____.
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CoASH; hypertension
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It is difficult to get biotin deficiency. This water soluble vitamin functions in _____ reactions.
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carboxylase
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Folic acid is involved in _____ synthesis.
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nucleotide
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Vitamin C is also called _____ acid. Lack of vitamin C causes _____.
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ascorbic; scurvy
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Vitamin B1 is known as _____. Vitamin B2 is known as _____.
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thiamin; riboflavin
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What B vitamin is thiamine? What kind of rxns is it involved in? What is the deficiency disease?
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It's B1. Aldehyde transfer reactions. Beri Beri.
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The cofactors of riboflavin are _____ and ____. Riboflavin is involved in ____ reactions.
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FAD; FMN; redox
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What vitamin (name and what "B") is most important for amino acid synthesis?
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pyridoxine, B6
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What are the fat soluble vitamins?
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A, E, D, and K
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Deficiency in which vitamin causes rickets?
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D
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Which organ might be described as an altruistic glucostat?
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the liver
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Which two hormones stimulate glycogen breakdown?
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epinephrine and glucagon
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What kind of receptors do epinephrine and glucagon bind to?
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G protein coupled receptors
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In relation to glycogen breakdown and synthesis inhibition, what enzyme does cAMP activate?
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protein kinase A
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How does protein kinase A affect glycogen synthase and glycogen phosphorylase?
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It phosphorylates both of them, however, by phosphorylating glycogen synthase, it changes it from the active a form to the inactive b.
By phosphoylating glycogen phosphorylase, it changes it from the inactive b to the active a. |
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What does PPP stand for? What are its important products?
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The pentose phosphate pathway. Makes NADPH and ribose.
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In glycolysis, an isomerase converts glucose-6-P into _____.
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fructose-6-P
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Why is the action of PFK-2 described as forward feedback?
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It produces fructose-2,6-bisphosphate, which allosterically actives PFK-1, which leads to more glycolysis.
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PFK-1 is activated by ____ and inhibited by _____ and ____.
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AMP; ATP; citrate
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Glyceraldehyde-3-phosphate (PGAL) is ______ to 1,3-bisphosphoglycerate. The enzyme responsible is a _______.
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oxidized; dehydrogenase
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The coenzyme NAD+ is made from ______.
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the B vitamin, niacin
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What is substrate level phosphorylation?
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ATP is made directly.... need to flesh this out, or not. I know what this means...
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What does phosphoglyerate kinase do?
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It takes a phosphate off one of the substrates to make ATP. It's kind of a misnomer. Usually, a kinase adds phosphate.
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What glycolysis enzymes drive substrate level phosphorylation?
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pyruvate kinase, phosphoglycerate kinase
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Which substrate level phosphorylation is irreversible?
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PEP ---> pryuvate by pyruvate kinase
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Which substrate level phosphorylation is irreversible?
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PEP > pryuvate by pyruvate kinase
(Remember, PEP is higher energy than ATP, so once ATP is created, it cannot drive the rxn in the opposite direction.) |
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Glycolysis takes place in the ____.
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cytoplasm
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Glucose can be created by breaking down stored _____.
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glycogen
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What kind of linkages does glycogen have?
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1,4 and 1,6
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What two kinds of tissue contain high levels of glycogen? Which has more?
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The liver and muscle. The muscle has more overall, but the liver has the highest concentration of glycogen.
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Glycogen levels are regulated by what two hormones?
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glucagon and insulin
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In muscle, glucose is converted to ____. In adipocytes, glucose is converted to _____.
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glycogen; stored fat
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What does glucagon do?
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It starts a cascade in the cell that inhibits glycogen synthesis when blood glucose levels are low
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Because muscle lacks _____, it cannot release glucose to the blood. Glucose can only be used to ____.
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glucose-6-phosphatase; create energy in the muscle cell
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As soon as glucose enters a cell, it is phosphorlyated by _____ to become _____.
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hexokinase; glucose-6-phophate
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What ions are required for hexokinase to function? What do they complex with?
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It needs Mg2+ (or Mn2+), which must complex with ATP.
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Brain hexokinase has a very ____ Km, while the Km of liver hexokinase is ____. This means that liver glucokinase is only active with ___ levels of blood glucose.
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low; high; high
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What does phosphoglucomutase do?
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It will change glucose-6-phosphate to glucose-1-phosphate.
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Glucose-1-phosphate + UTP = what?
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glucose-UDP and pyrophosphate
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The ____ end of the glucose in glycogen is tied up in a glycogen bond, while the ___ end is free to bond.
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reducing; nonreducing
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Glycogen synthesis is catalyzed by ______. What kind of bond is formed?
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glycogen synthase; this enzyme forms the 1,4 bond
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Which enzyme forms the 1,6 bond of glycogen?
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a branching enzyme
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If glycogen synthase can only add glucose to existing glycogen, how does the whole thing get started?
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Glycogenin creates primer 1-4 chains attached to tyrosine residues.
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Glycogenolysis is catalyzed by ____ in the presence of _____.
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glycogen phosphorylase; inorganic phosphate
This is like hydrolysis, except with phosphate. It's called phosphorolysis. |
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What is the product of glycogenolysis?
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glucose-1-phosphate
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In the liver, what does glucose-6-phosphatase do? Where in the cell is this enzyme located?
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It's in the ER. This enzyme removes phosphate from glucose-6-phosphate, so the free glucose can get back into the bloodstream.
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Which two hormones set off the cAMP cascade to stimulate glycogen breakdown?
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This can be done by either glucagon OR epinephrine.
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Epinephrine and glucagon stimulate glycogen breakdown. What else do they do?
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The inhibit glycogen synthase by converting it to its inactive form.
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Epinephrine and glucagon work by activating _____ and deactivating _____ (by phosphorylating both!).
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glycogen phosphorylase; glycogen synthase
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What is a futile cycle?
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It's a process that wastes energy. For instance, if glycogen synthesis and breakdown happened equally, it would waste energy. G-1-P --> UDPG---> glycogen---> G-1-P ---> UDPG, etc.
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What are the possible fates of glucose-6-phosphate?
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1. glycolysis
2. glycogen synthesis 3. free glucose 4. PPP |
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Most of the regulation of glycolysis occurs around which step?
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When PFK (phosphofructokinase) converts fructose-6-phosphate to fructose-1,6-bisphosphate.
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The conversion of F-6-P to F-2,6-BP instead of F-1,6-BP is an example of what kind of regulation?
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"Feed-forward" regulation. The 2,6 activates PFK to create more 1,6 and continue glycolysis.
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PFK is inhibited by high levels of what two things?
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ATP (too much energy already) and citrate (means TCA cycle already has enough). (ex of local regulation)
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Why on earth does insulin stimulate PFK-2 (which promotes glycolysis)?
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A product of glycolysis is acetylCoA, which is also used to build FATTY ACIDS. These fats are another way of storing glucose, and thus, the end result will be to get glucose out of the blood. (ex of systemic regulation)
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High levels of ____ indicate low energy in a cell and will stimulate glycolysis.
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AMP
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When F-1,6-BP is cleaved, what two products are possible? Which one continues in glycolysis?
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DHAP and and PGAL (aka G-3-P). PGAL goes on. DHAP can be converted to a glycerol backbone for membrane lipids.
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When an intermediate in glycolysis is _____, NAD+ can be _____.
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oxidized; reduced to NADH
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The _____ that catalyzes production of PEP (in glycolysis) is inhibited by fluoride.
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enolase
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Which intermediate of glycolysis is more high energy than ATP?
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PEP
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What are the products of glycolysis?
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2 pyruvate, 2 ATP, 2 NADH, 2 H+, 2 H2O
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What happens to NADH and pyruvate in anaerobic glycolysis?
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NADH reduces pyruvate to ethanol or lactate (important in tooth demineralization). This regenerates NAD+.
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Is fluoride an essential nutrient?
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maybe
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Vitamins:
1. vision 2. clotting |
1. A
2. K |
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_____ is the base of all aldoses.
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Glyceraldehyde
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_____ is the base of all ketoses.
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Dihydroxyacetone
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Which is an alpha bond? Beta bond?
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Alpha is when the OH is down. Beta is when it's up.
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Glucose + fructose = ___. Describe the glycosidic bond. Is it a reducing sugar?
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sucrose; the bond is alpha for the glucose, beta for the fructose. It is not reducing
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Fiber can decrease absorption of dietary ______.
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cholesterol
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Which glucose polymer is indigestible? How does it differ from the other forms.
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Humans cannot digest cellulose. Cellulose, unlike starch and glycogen, is not branched.
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Storing carbs as polymers helps control ____ pressure, as each polymer is only counted as one unit.
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osmotic
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Salivary and pancreatic ____ break down glycosidic bonds.
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amylases
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Which mitochondrial membrane is more permeable?
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The outer membrane is more permeable. The inner membrane is relatively impermeable
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During TCA, are there more protons inside or outside the mitochondria?
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The protons are being pumped out of the inner membrane, so there is a gradient, with more protons outside.
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What are the four major products of TCA?
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CO2, NADH, FADH2, GTP
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Pyruvate must be _____ to become Ac-S-CoA
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decarboxylated
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What multienzyme array in the mitochondria is responsible for transforming pyruvate into Ac-S-CoA?
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pyruvate dehydrogenase
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The carboxyl group of pyruvate is released as what?
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CO2 (release of CO2 is a powerful driver of this rxn) and H+
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What might inhibit the formation of Ac-S-CoA from pyruvate? What might drive it?
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Inhibitors:
build up of Ac-S-CoA, build up of NADH, build up of GTP Drivers: high levels of AMP |
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____ of pyruvate dehydrogenase at a specific serine residue inactivates the compound.
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Phosphorylation
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In adipose tissue, ____ increases PDH activity because Ac-S-CoA is required for fatty acid synthesis.
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insulin
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When does oxaloacetate come into the TCA cycle?
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It condenses with Ac-S-CoA to form citrate and CoASH.
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Isocitrate undergoes the first oxidation. What does it lose? What is produced?
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It loses a carboxyl group. The H adds to NAD+ to form NADH. The rest is lost as CO2.
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For oxidative phosphorylation, which two enzymes must be available and regenerated as part of the process?
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I'm sure there are many, but we focused on free CoA (CoASH) and NAD+.
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Does substrate level phosphorylation occur during TCA? When?
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Yes. As succinyl-CoA become succinate, inorganic phosphate transfers directly to GDP to form GTP.
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What happens to succinate? What coenzyme is involved?
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It is oxidized by FAD. (FAD --> FADH2)
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Through a series of rxns, succinate will eventually be transformed back into what?
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oxaloacetate
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Succinate ---> ______ -----> ______ -----> oxaloacetate
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fumarate; malate
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Are the enzymes of TCA linked?
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Maybe... probably? Maybe yes, but it's theoretical.
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Which TCA step requires FAD?
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succinate to fumarate
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What is the main reculator of oxphos (high levels will upregulate)? What element is needed in the tissues for this cycle to occur?
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ADP; oxygen
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During OxPhos, what will happen to these: NADH, ADP, and O2?
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NADH -->NAD+
ADP --> ATP O2 -->H20 |
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What are cytochromes? What important group do they have?
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They're proteins with a heme group that function in OxPhos. The heme gets reversibly oxidized and reduced (Fe3+ and Fe2+).
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Which OxPhos complex brings H+ back INTO the mitochondrial matrix?
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Complex 5. This entrance drives the synthesis of ATP.
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What is coQ?
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It's an enzyme in the mitochondrial matrix that's active during oxphos. It carries redox potential by switching back and forth from quinone to semiquinone.
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What is the
"motor" enzyme that spins to make ATP? |
ATP synthase
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What substance's presence has the most control over the rate of respiration?
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ADP
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What kind of tissue is specialized for "uncoupling" in nonshivering thermogenesis?
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brown fat
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Which protein allows protons back into the matrix without producing ATP? What other protein upregulates the expression of this protein?
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UCP (uncoupling protein). Lectin upregulates UCP.
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The process by which ox phos creates destructive byproducts is called what?
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oxygen stress
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What are ROS?
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Reactive Oxygen Species (products from oxygen stress)
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How many ATP do we get for each intramitochondrial NADH? FADH2?
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NADH: 2.5
FADH2: 1.5 |
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What are the two shuttles used to get NADH into the mitochondria?
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malate-aspartate
glycerol-phosphate (brain, skeletal muscle) |
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Which NADH shuttle results in less ATP production?
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The glycerol-phosphate shuttle converts NADH to FADH2, so instead of 2.5 ATP per, 1.5 ATP are instead produced. (NB: This occurs in the brain and skeletal muscle)
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How many TOTAL ATPs will be produced from the products of glycolysis?
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5 or 7 (depending on whether malate-aspartate or glucose-phosphate shuttle is used)
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How many ATPs produced from pyruvate dehydrogenase?
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5 (from 2 NADH)
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How many ATP from TCA?
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20
(2 FADH2, 6 NADH, 2 GTP) |