Ch. 9 Cellular Respiration Flashcards
What is the balanced equation for cellular respiration?
C6H12O6+ 6 O2 -> 6 CO2 + 6 H2O+ energy that is used to rebuild ATP from ADP + Pi
What is oxidation?
A substance loses electrons or is oxidized
What is reduction?
A substance gains electrons or is reduced
How are these reactions coupled?
Oxidation is the release of an electron (similar to exergonic)
Reduction is the gain of an electron (similar to endergonic)
A coupled reaction is a reaction that uses energy from an exergonic reaction to fuel an endergonic reaction
Understanding H atoms are comprised of one electron and one proton (no neutrons) Part I:
When a molecule loses one hydrogen atom, it loses one electron. Therefore, when a molecule loses H, it gets oxidized
Understanding H atoms are comprised of one electron and one proton (no neutrons) Part II:
When a molecule gains one hydrogen atom, it gain one electron. Therefore, when a molecule gains H, it is reduced
Hydrogen atoms (H) gains/loss represents electron gain/loss in oxidation/reduction reactions
To track electrons in oxidation/reduction, track hydrogen atoms
Glucose is oxidized (CO2 remains), and NAD+ and FAD are reduced (this forms NADH and FADH2)
Takes places during the Glycolysis and the Citric Acid Cycle
NADH and FADH2 are oxidized (NAD+ and FAD remains), and O2 is reduced (this forms H2O)
Takes place during Oxidative phosphorylation
What are the 3 stages of cellular respiration?
Glycolysis, The Citric Acid Cycle (includes formation of Acetyl-CoA), Oxidative phosphorylation (Electron transport chain and Chemiosmosis)
Why is glucose broken down in so many small stages?
The harvesting of energy from glucose by cellular respiration is a cumulative function of three metabolic stages. Is broken down in Glycolysis and then pyruvate oxidation and the Citric Acid Cycle.
What is the difference btw aerobic and anaerobic respiration
Aerobic respiration: uses O2
Anaerobic respiration: does NOT use O2
Big Picture of Cellular Respiration
Glucose is broken down (exergonic reactions), and potential energy stored in the chemical bonds of glucose is used to rebuild ATP (endergonic reactions)
ADP + Pi + energy = ATP (this is endergonic)
Why is ATP continuously rebuilt?
The energy contained in ATP is used to carry out all types of work in the cell
Breaking down glucose is exergonic; the rebuilding of ATP is endergonic. What is this an example of?
Reactions are coupled
What stage is ATP produced in?
Glycolysis, Citric Acid Cycle, Electron Transport Chain (Oxidative Phosphorylation).
Mostly produced in the Oxidative Phosphorylation
What stages is NADH produced in?
Glycolysis, Citric Acid Cycle, Mostly produced in Citric Acid Cycle
What stages is FADH2 produced in?
Citric Acid Cycle, Mostly produced here
What stages is CO2 produced in?
Citric Acid Cycle, mostly produced here too
What stage is H2O produced in?
Oxidative Phosphorylation (Electron Transport Chain). Mostly produced here
What occurs during the glycolysis stage?
A type of anaerobic respiration where it breaks down glucose, splits glucose into two molecules of pyruvate
Net energy yield: 2 Pyruvates + 2H2O, 2ATP and 2NADH + 2H+(takes place in the cytosol)
What is the product that is produced? This product proceeds to the next stage.
Pyruvate yields 3 CO2 (carbon dioxide) molecules that is converted to Acetyl CoA which later joins the Citric Acid Cycle
Glycolysis is the only stage of cellular respiration with an energy investment phase. What/how much ‘energy’ is input in this phase?
Spends 2 ATP
Does glycolysis require the presence of oxygen? (Is this stage aerobic or anaerobic?)
No, this stage is anaerobic
Where in the cell does glycolysis take place?
The cytosol (cytoplasm)
At the end of glycolysis, will cellular respiration always proceed (continue)? Or will fermentation proceed? Explain.
If oxygen is present then it proceeds to cellular respiration and if no oxygen is present then fermentation will occur
What is the mini step that occurs at the beginning of the stage 2 (citric acid cycle):
Pyruvate is converted to acetyl-CoA
What occurs during the Acetyl-CoA conversion?
- Pyruvate is oxidized and gives off a molecule of CO2
- Remaining 2-carbon fragment is oxidized and the electrons transferred to NAD+, storing energy in a form of NADH
- coenzyme A (CoA), is attached via it’s surfer atom to the 2-carbon intermediate, forming Acetyl CoA
What molecule does Acetyl-CoA join to begin the citric acid cycle?
Oxaloacetate
What is the first molecule produced in the Citric Acid Cycle?
Citrate
What molecule is regenerated at the end of the Citric Acid Cycle?
Oxaloacetate
How many turns of the Citric Acid Cycle take place during the breakdown of 1 molecule of glucose?
Twice because there are 2 pyruvates
Where in the cell does the citric acid cycle take place? BE SPECIFIC.
The Mitochondrion, in the mitochondrial matrix
What kind of molecules comprise the electron transport chain?
Most components of the chain are proteins
What molecules provide (the H atoms which provide) the electrons which travel through the electron transport chain? Be specific
NADH and FADH2; each donate an equivalent number of electrons (2) for oxygen reduction.
What happens to the electrons during their trip through electron transport chain?
Electrons drop in free energy as they go down the chain, releasing energy to drive chemiosmosis
What molecule is the final electron acceptor in Electron transport chain?
Oxygen (O2)
What happens to the energy given off by the transfer of electrons (oxidation-reduction reactions) during the electron transfer chain? It does NOT go to building ATP.
It drives chemiosmosis
Where in the cell does the electron transport chain take place? BE SPECIFIC.
Inner mitochondrial membrane/ inner membrane of the mitochondrian
What molecules provide (the H atoms which provide) the protons, which undergo chemiosmosis? Be specific
NADH and FADH2
What happens to the protons in Chemiosmosis? Where in the cell does this take place? BE SPECIFIC.
The protons are pumped out of the matrix/ released into surrounding solution
Proton-motive force
The potential energy stored in the form of a proton electrochemical gradient, generated by the pumping of hydrogen ions (H+) across a biological membrane during chemiosmosis
What directly (immediately) supplies the energy needed to fuel Chemiosmosis?
The Electron Transport Chain
What is the role of ATP synthase?
It harnesses the proton-motive force to phosphorylate ADP, forming ATP
What generates the energy to fuel the formation of ATP from ADP + P?
Proton gradient across the membrane/ the proton motive force
What role does oxygen play? (Know the specific details of its role; why is it necessary to breath?)
Oxygen is used as the end electron acceptor for the electron transport chain. Allows electrons to be transferred through the electron transport chain in order to create an electrochemical gradient for hydrogen to create ATP
In what stage(s) of cellular respiration does oxygen play a role?
Pyruvate oxidation, citric acid cycle and oxidative phosphorylation
How is water formed at the end of cellular respiration? BE SPECIFIC.
Each O (oxygen) picks up a pair of hydrogen ions (protons) from the aqueous solution, neutralizing the -2 charge of the added electrons and forming water
What molecule is reduced to form water?
Oxygen (goes from O2 to O)
