Cellular Respiration Flashcards
Organisms store glucose as…
Glycogen or starch.
In cells, glucose is oxidized by…
A long series of redox reactions. The released free energy is used to synthesize ATP. Known as cellular respiration.
4 processes of cellular respiration
Glycolysis, pyruvate processing, citric acid cycle, and electron transport/oxidative phosphorylation.
Glycolysis
Sequence of enzyme catalyzed reaction by which glucose is converted into pyruvate.
What are the 4 enzymes in the 4 steps of the glycolysis prep phase?
Hexokinase, phosphohexose isomerase, phosphofructokinase-1, and aldolase.
What is produced at the end of the prep phase in glycolysis?
Glyceraldehyde 3-phosphate, dihydroxyacetone phosphate, and 2 ADP.
What are the 6 enzymes in the 6 steps of the glycolysis payoff phase?
Triose phosphate isomerase, glyceraldehyde 3-phosphate dehydrogenase, phosphoglycerate kinase, phosphoglycerate kinase, phosphoglycerate mutase, enolase, and pyruvate kinase.
What is produced at the end of glycolysis?
2 pyruvate, 2 NADH, 2 H, 2 H2O and 2 ATP.
Tautomerization
Effectively lowers the concentration of the reaction product, drives reaction towards ATP formation.
How is glycolysis regulated?
Feedback inhibition. High levels of ATP inhibit the third enzyme, phosphofructokinase.
What happens to phosphofructokinase when there is too much ATP?
Phosphofructokinase has two binding sites for ATP; when ATP binds the the active site the reaction continues, when ATP levels are too high, it will bind the regulatory site and inhibits the enzyme
Substrate-level phosphorylation
Occurs when ATP is produced by the enzyme-catalyzed transfer of a phosphate group from an intermediate substrate to ADP. How ATP is produced in glycolysis and the citric acid cycle.
What is used in glycolysis (consumed)?
1 glucose, 2 ATP, 2 NAD+
What is produced in glycolysis?
2 pyruvate, 4 ATP, 2 NADH
Net amount of ATP production at the end of glycolysis
2 ATP
Fates of pyruvate
Anaerobic conditions (fermentation) or aerobic conditions (citric acid cycle).
Cristae
Extensions of the inner mitochondrial membrane.
Mitochondrial matrix
Inside the inner mitochondrial membrane.
Where does pyruvate processing take place?
Enzyme complex called pyruvate dehydrogenase in mitochondrial matrix (eukaryotes).
What are the series of reactions that pyruvate undergoes?
One of its carbon’s is oxidized to CO2, NADH is produced, and the remaining two carbon unit is attached to coenzyme A producing acetyl CoA.
What does thiamine deficiency result in
In sufficient pyruvate dehydrogenase activity.
What are the 8 enzymes of the citric acid cycle?
Citrate synthase, aconitase, isocitrate dehydrogenase, alpha ketongluatarate dehydrogenase, succinyl-coA sythetase, succinate dehyrdogenase, fumarase, malate dehydrogenase
What is the net results of the citric acid cycle?
2 CO2, 3 NADH, FADH2, GTP, CoA, 3 H+
Amphibolic
Relates to both catabolism and anabolism.
Glucose is completely oxidized to CO2 by…
Glycolysis, pyruvate processing, and the citric acid cycle
As glucose is oxidized, free energy becomes…
More negative
For each molecule of glucose that is oxidized, the cell produces…
6 CO2, 4 ATP, 10 NADH, and 2 FADH2.
What happens to the reduced electron carriers after glucose oxidation?
NAD+ is a reduced electron carrier in glucose oxidiation because it is used to accept the electrons. FADH is used as well. NADH and FADH2 (the reduced form) moved to the electron transport chain donates a pair of electrons. Electrons are ultimately transferred to oxygen to form water.
Where do NADH and FADH2 get oxidized?
In the inner membrane of the mitochondria, the electron transport chain.
Ubiquinone (coenzyme Q)
Lipid-soluble, non-proteins part of the ETC.
What are the four protein complexes of the ETC?
NADH-Q oxidoreductase, succinate Q reductase, Q-cytochrome c oxidoreductase, and cytochrome c oxidase.
In what complex does NADH get oxidized?
Complex I, NADH dehydrogenase.
In what complex does FADH2 get oxidized?
Complex II, succinate dehydrogenase.
ADP to ATP is highly…
Thermodynamically unfavorable.
Chemiosmosis
The process of driving protons through a proton channel in ATP synthase to produce ATP from ADP.
ATP production is dependent on…
A proton-motive force generated by the proton electrochemical gradient.
The conclusion of the chemiosmotic hypothesis was…
The linkage between the ETC and ATP production by ATP synthase is indirect; the synthesis of ATP only requires a proton gradient.
What are the two components of ATP synthase?
An ATPase “knob” (F1 unit) and a membrane-bound proton-transporting base (F0 unit).
Which unit of ATP synthase phosphorylates ADP?
The F0 unit spins, changing the conformation of the F1 unit so that it can phosphorylate ADP to ATP.
What happens when the proton gradient stops?
ATP synthase can reverse direction to hydrolyze ATP to pump protons from the matrix to the intermembrane space.
Malate-aspartate shuttle
Transfers reducing equivalents into the mitchondrion for the liver, kidney and heart.
Glycerol-3-phosphate shuttle
Transfers reducing equivalents into the mitochondrion for the skeletal muscles and the brain.
For each glucose molecules that is oxidized to 6 CO2, the cell…
Reduces 10 molecules of NAD+ to NADH and 2 molecules of FAD to FADH2, and produces 4 molecules of ATP by substrate level-phosphorylation.
Oxygen is the most effective electron acceptor because…
It is highly electronegative, a large difference exists between the potential energy of electrons in NADH and O2 and it allows the generation of a large proton-motive force.
Fermentation
Metabolic pathway that regenerate NAD+ from NADH. Glycolysis can continue to produce ATP by substrate-level phosphorylation in the absence of oxygen.
Lactic acid fermentation
Pyruvate produced by glycolysis accepts electrons from NADH.
Homeostasis
Maintains a stable internal environment even under different environmental conditions.
Hexokinase
1 enzyme in glycolysis, uses ATP to add phosphate to glucose, irreversible.
Phosphoglucose isomerase
2nd enzyme in glycolysis, opens ring, moves carbonyl group from 1st carbon to 2nd, then closes ring. It is reversible.
Phosphofructokinase
3rd enzyme in glycolysis, uses ATP to add phosphate, irreversible, major check point.
Aldolase
4th enzyme in glycolysis, rings opens and fructose 1,6 - biphosphate is cleaved into 2 molecules.
Triosphosphate isomerase
5th enzyme in glycolysis, catalyzes dehydroxyacteone phosphate into glyceraldehyde 3-phosphate.
Glyceraldehyde 3- phosphate dehydrogenase
6th enzyme in glycolysis, uses NAD+ to oxidize glyceraldehyde 3-phosphate.
Phosphoglycerate kinase
7th enzyme in glycolysis, dephosphorylates, Pi is transferred to ADP.
Phosphoglycerate mutase
8th enzyme in glycolysis, moves phosphate group.
Enolase
9th enzyme in glycolysis, removes H20 and creates a phosphate group with extremely high free energy of hydrolysis.
Pyruvate kinase
10th enzyme in glycolysis, transfers high energy phosphate to ADP. 2 pyruvate are formed.
