Busy. Please wait.
or

show password
Forgot Password?

Don't have an account?  Sign up 
or

Username is available taken
show password

why


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account.
We do not share your email address with others. It is only used to allow you to reset your password. For details read our Privacy Policy and Terms of Service.


Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.
Don't know
Know
remaining cards
Save
0:01
To flip the current card, click it or press the Spacebar key.  To move the current card to one of the three colored boxes, click on the box.  You may also press the UP ARROW key to move the card to the "Know" box, the DOWN ARROW key to move the card to the "Don't know" box, or the RIGHT ARROW key to move the card to the Remaining box.  You may also click on the card displayed in any of the three boxes to bring that card back to the center.

Pass complete!

"Know" box contains:
Time elapsed:
Retries:
restart all cards
share
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

USMLE

New FA Biochem 5

QuestionAnswer
What are the net reactants and products in glycolysis. Reactants: 1. Glucose 2. 2 Phosphates 3. 2 ADP 4. 2 NAD Products: 1. 2 Pyruvate 2. 2 ATP 3. 2 NADH 4. 2 H+ 5. 2 H20
What are the rate limiting steps of glycolysis? 1. Hexokinase (Glucose to Glucose-6-P) 2. *Phosphofructokinase-1 (Fructose-6-P to Fructose-1,6-BP) 3. Pyruvate kinase (Phosphoenolpyruvate to Pyruvate)4. Pyruvate dehydrogenase (Pyruvate to Acetyl-CoA)
Phosphofructokinase-1: What does it do, and what stimulates and inhibits it? PFK-1 1-phosphorylates fructose-6-phosphate to produce Fructose-1,6-BP. Inhibited by: 1. ATP (plenty of me) 2. Citrate (my cycle's going well) Stimulated by: 1. AMP (more ATP please) 2. Fructose-2,6-BP (making me means there's tons of glucose already)
Pyruvate kinase: What does it do, and what stimulates and inhibits it? Pyruvate kinase converts phosphoenolpyruvate to pyruvate, producing 2 ATP. Inhibited by: 1. ATP (plenty of me) 2. Alanine (I came from pyruvate, plenty of me.)Stimulated by: 1. Fructose-1,6-BP(I heard we needed more ATP, get the line moving!)
Pyruvate dehydrogenase: What does it do, and what stimulates and inhibits it? Pyruvate dehydrogenase converts pyruvate to acetyl-coA, producing NADH & CO2. Stimulated by: excess pyruvate? Inhibited by: 1. NADH (plenty. Besides, you produce NADH, soon there'll be even more of me) 3. Acetyl-CoA (Enough of me, save your pyrvuate.)
What disease state is glycolytic enzyme deficiency generally associated with? Hemolytic anemia
What is the mechanism of hemolytic anemia in someone with glycolytic enzyme deficiency? 1. Lack of glycolysis leads to lack of ATP in RBCs. 2. Lack of ATP leads to inactivity of Na, K-ATPase pump. 3. Lack of the pump leads to sodium influx. 4. Water follows sodium into the cell. 5. The cell swells and bursts.
What are the two most common glycolytic enzyme deficiencies? Pyruvate kinase (95% of cases) followed by glucose phosphate isomerase (4% of cases)
What are the 5 cofactors necessary for pyrvuate dehydrogenase? Lipoic acid plus the first four B vitamins in their active forms: 1. B1: TPP 2. B2: FAD 3. B3: NAD 4. B5: CoA
What are the 5 cofactors necessary for alpha-ketoglutarate dehydrogenase? Lipoic acid plus the first four B vitamins in their active forms: 1. B1: TPP 2. B2: FAD 3. B3: NAD 4. B5: CoA
What are the net reactants and products in the reaction that Pyruvate Dehydrogenase catalyzes? Reactants: 1. Pyruvate 2. CoA 3. NAD Products: 1. Acetyl CoA 2. CO2 3. NADH
What activates and what inhibits pyruvate dehydrogenase? Activated by exercise, which stimulates: 1. Increased NAD/NADH ratio (need more NADH) 2. Increased ADP (need more ATP) 3. Ca2+ (I tell PDH in mito we need more ATP) Inhibited by: 1. NADH (plenty of me) 2. ATP (ditto) 3. Acetyl CoA (ditto)
Lipoamide or lipoate: Which carries aldehydes? Lipoamide
Lipoamide or lipoate: Which is a cofactor for pyruvate dehydrogenase? Lipoate (Lipoic acid)
What toxin inhibits lipoic acid? Arsenic
What is the presentation of arsenic toxicity? 1. Vomiting 2. Rice water stools 3. Garlic breath
Pyruvate dehydrogenase deficiency: Mechanism Backup of pyruvate and alanine leads to lactic acidosis.
Pyruvate dehydrogenase deficiency: Congenital or Acquired Both. Acquired cases happen in cases of B1 deficiency (such as in alcoholics.)
Pyruvate dehydrogenase deficiency: Presentation Lactic acidosis and neurologic defects
Pyruvate dehydrogenase deficiency: Treatment Increased intake of ketogenic nutrients (such as high fat content or increased lysine and leucine)
What are the miscellaneous fates of pyruvate, and what are the end products used for? 1. Alanine: Carries amino groups to the liver from muscle 2. Oxaloacetate: Replenishes TCA cycle or is used gluconeogenesis 3. Acetyl-CoA: Used in TCA cycle 4. Lactate: No good use
Which tissues and organs primarily convert pyruvate into lactate? 1. RBCs and WBCs 2. Lens and cornea 3. Renal medulla 4. Testes
What enzymes and cofactors are used in conversion of pyruvate to alanine? Enzyme: Alanine Transaminase (ALT) Cofactors: None
What enzymes and cofactors are used in conversion of pyruvate to oxaloacetate? Enzyme: Pyruvate Carboxylase (contains biotin and magnesium) Cofactors: CO2 and ATP
What are the reactants and products in the reaction catalyzed by pyruvate carboxylase? Reactant: Pyruvate (with CO2 and ATP) Product: Oxaloacetate
What are the reactants and products in the reaction catalyzed by lactate dehydrogenase? This reaction is reversible, so the products can switch with the reactants. Reactants: 1. Pyruvate 2. NADH (rehydrogenates in this direction) 3. H+ Products: 1. Lactate 2. NAD
Where do the various pyruvate transformation reactions happen? Cytosol: 1. ALT (Alanine to/from pyruvate) 2. LDH (Lactate to/from pyruvate) Mitochondria: 1. Pyruvate carboxylase (pyruvate to oxaloacetate) 2. Pyruvate dehydrogenase (pyruvate to acetyl-CoA)
Where does the Cori Cycle happen? In the liver and muscle/RBCs Liver: Pyruvate converts to glucose Muscle/RBCs: Glucose converts to Pyruvate
What is the purpose of the Cori cycle? Transfers excess reducing equivalents from RBCs and the muscle to liver so they can function anaerobically
What reaction does citrate synthase catalyze? Oxaloacetate and acetyl coA combine to yield citrate.
What is the order of the citric acid cycle beginning at citrate? “CAn I Keep Selling Sex For Money, Officer?” 1. Citrate 2. cis-Aconitate 3. Isocitrate 4. alpha-Ketoglutarate 5. Succinyl CoA 6. Succinate 7. Fumarate 8. Malate 9. Oxaloacetate
What stimulates and inhibits citrate synthase? Stimulate: Nothing Inhibit: ATP
What stimulates and inhibits isocitrate dehydrogenase? Stimulate: ADP Inhibit: 1. ATP 2. NADH
What stimulates and inhibits alpha-ketoglutarate dehydrogenase? Stimulate: Nothing Inhibit: 1. ATP 2. NADH 3. Succinyl CoA
Which steps in the citric acid cycle produce CO2? The steps where carbons are lost, the two structures after isocitrate each have one less carbon than the last. 1. Isocitrate to alpha-ketoglutarate 2. alpha-ketoglutarate to succinyl coA
Which steps in the citric acid cycle produce reducing equivalents? The only step that produces FADH2 is the only one that also yields an F product. 1. Isocitrate to alpha ketoglutarate (1 NADH) 2. alpha-ketoglutarate to succinyl coA (1 NADH) 3. Succinate to Fumarate (1 FADH2) 4. Malate to Oxaloacetate (1 NADH)
Which steps in the citric acid cycle produce ATP? None, however 1 GTP is produced from the conversion of Succinyl CoA to Succinate.
How much ATP is produced by the citric acid cycle per molecule of acetyl coA? 12 ATP. 3 NADH x 3 ATP/NADH= 9 ATP 1 FADH2 x 2 ATP/FADH2 = 2 ATP 1 GTP x 1 ATP/GTP = 1 ATP
How much ATP is produced by the citric acid cycle per molecule of glucose? 24 ATP. 1 cycle: 3 ATP/NADH= 9 ATP 1 FADH2 x 2 ATP/FADH2 = 2 ATP 1 GTP x 1 ATP/GTP = 1 ATP The total is 12 ATP per acetyl coA. However, there are 2 acetyl coA molecules produced per glucose molecule. Thus the total is 24.
Created by: Asclepius