Miscellaneous
In enzyme kinetics, what does (α) stand for?
What part of the cell does Glycolysis take place?
Cytosol
Lysine - AKA Lipoyllysine
What products of glucose oxidation are essential for oxidative phosphorylation?
NADH and FADH2
High cellular concentrations of what molecule would inhibit the entry of pyruvate into the citric acid cycle?
D. NADH
Name the 3 types of catalysis.
False. It is reversible.
What is the role of the E3 bound FAD?
Accepts 2 electrons from the reduced lipoamide, regenerating the re-oxidized form to allow the cycle to repeat.
What is the effect of increased levels of hydrogen ions in the inter-membrane space of the mitochondria?
Increase in ATP production
What are the 3 irreversible steps of the Citric Acid Cycle and why are the irreversible?
They are highly exergonic and thus irreversible.
Why is NADH worth 2.5 ATP and FADH2 worth 1.5 ATP?
Difference is due to where the two carriers enter the ETC. NADH enters at complex I and FADH2 enters at Complex II.
When you enter the ETC at an earlier complex, you can pump more H+ thus generating more ATP.
A kinase is an enzyme that uses ATP to transfer...
An inorganic phosphate group.
How is the pyruvate dehydrogenase complex regulated?
High energy state of the cell inactivates PDC (ATP, NADH).
Sudden demands on the cell (exercise for example)
Low energy state will inhibit activity of PDC (AMP, ADP, NAD+)
Product inhibition (Large [acetyl CoA])
What would occur if all available hydrogen ions were used by ATP synthase?
a. It would increase the ph of the mitochondrial intermembrane space
b. It would increase the pH of the mitochondrial matrix
c. It would decrease the levels of inorganic phosphate in the intermembrane space
d. It would increase the levels of inorganic phosphate in the mitochondrial matrix
a. It would increase the ph of the mitochondrial intermembrane space.
What steps are CO2 produced at (oxidative decarboxylations)?
Disulfiram binds to the active site of the enzyme aldehyde oxidase, blocking the binding of its substrate. What kind of inhibitor is disulfiram?
Gluconeogenesis must use bypass reactions to circumvent three reactions in the glycolytic pathway. Reactions carried out by which 3 enzymes listed must be bypassed...
1. Hexokinase
2. Phosphoglycerate kinase
3. PFK-1
4. Pyruvate kinase
5. Triosphosphate isomerase
1. Hexokinase, 3. PFK-1, 4. Pyruvate kinase
What are some alternative metabolic destinations of pyruvate (two examples)?
Conversion to acetyl-CoA by PDHC, used for fatty acid synthesis
Carboxylation of oxaloacetate for gluconeogenesis or citric acid cycle
Synthesis of amino acids
Reduced to lactate
How are electrons extracted from the citric acid cycle for use in the electron transport chain?
NAD+ and FAD get reduced where they can transfer electrons to complex 1 and 2 respectively.
Why does calcium stimulate the citric acid cycle?
When your muscles contracts, you are using energy which means the energy needs to be regenerated.
It activates isocitrate dehydrogenase, pyruvate dehydrogenase, and α- ketoglutarate dehydrogenase.
A researcher adds 1M of competitive inhibitors to an existing solution of substrate and enzyme. The researcher notices that the effect of the enzyme decreases. What can the researcher do to increase the effect of the enzyme back to normal levels (to levels before inhibitors were added)? Why?
For every glucose generated by gluconeogenesis, how many ATP and GTP are needed, and where from?
4 ATP,
They come from pyruvate carboxylase and phosphoglycerate kinase.
2 GTP,
They come from pyruvate carboxykinase
People with Berberi, a disease caused by a thiamine deficiency, have elevated levels of blood pyruvate and a-ketoglutarate, especially after consuming a meal rich in glucose. How are these effects related to a deficiency in thiamine?
Thiamine is required for the synthesis of thiamine pyrophosphate (TPP), a prosthetic group in the pyruvate dehydrogenase and a-ketoglutarate dehydrogenase complex.
A thiamine deficiency reduces activity of these enzyme complexes and causes observed accumulation of the precursors.
With respect to their relative pH, how do the cytosol, intermembrane space of the mitochondria, and the mitochondrial matrix compare?
a. pH of the mitochondrial matrix<pH of cytosol<pH of intermembrane space
b. pH of mitochondrial matrix>pH of cytosol>pH of intermembrane space
c. pH of cytosol of cytosol>pH of intermembrane space = pH of mitochondrial matrix
d. pH of intermembrane space < pH of mitochondrial matrix < pH of cytosol
b. pH of mitochondrial matrix>pH of cytosol>pH of intermembrane space
Why is oxaloacetate the rate limiting step Citric Acid Cycle?
It is the rate limiting step because it depends on the concentration of oxaloacetate. Oxaloacetate binds causing a conformational change exposing acetyl-CoA’s binding site.
If oxaloacetate concentration is low, it won’t be available to allow for this conformational change and acetyl-CoA cannot bind active site of citrate synthase.