cellular respiration Flashcards
where does glycolysis occur?
cytoplasm/cytosol
Glycolysis
Glucose is split into two pyruvates in the cytoplasm
Net yield of Glycolysis
2 ATP, 2 Pyruvate and 2 NADH
What is NADH?
A coenzyme that has the ability to transfer electrons
Intermediate step after glycolysis
2 pyruvates are transported into the mitochondria (specifically the mitochondrial matrix), the pyruvate is oxidised, then converted into 2 acetyl coA
Carbon dioxide is released and 2 NADH are produced
Krebs Cycle (citric acid cycle)
- Aerobic Process
- Carbon dioxide is released
- 2 ATP is produced
- 6 NADH is produced
- 2 FADH2 is produced
FADH2
A coenzyme, like NADH, assists transferring electron to produce more ATP.
Electron Transport Chain/ Chemiosmosis
- Occurs in the inner mitochondrial membrane
- Oxygen is required
- Electrons are transferred from the NADH and FADH2, to protein complexes, in electron carriers.
- The electrons are used to generate a proton gradient, as protons are put into the intermembrane space.
- Protons travel through ATP synthase
- ATP synthase makes ATP by adding a phosphate to ADP.
- Essentially, protons travel down the electrochemical gradient, through a portion of the ATP synthase, powering it to make ATP.
TOTAL ATP YIELD
36-38 net ATP molecules per glucose molecule.
Oxygen is the final….
electron acceptor (end transport chain)
Fermentation
The process by which organisms produce ATP without oxygen, through an ‘extended glycolysis’.
There are 2 types of fermentation:
- Alcoholic fermentation
- Lactic acid fermentation
Alcoholic fermentation
- Done by yeast
- Glycolysis occurs
- 2 pyruvates are used which produces carbon dioxide and 2 ethanol. This also produces the derivative of pyruvate, 2 acetaldehydes, which can act as electron acceptors. Therefore the 2 NADH can be oxidised back to 2 NAD+
- Therefore glycolysis can occur again.
- Ethanol (the alcohol) is a waste product
Alcoholic fermentation is an anaerobic process in which glucose is broken down by yeast or certain bacteria to produce ethanol, carbon dioxide, and ATP. The reaction occurs in the absence of oxygen and follows glycolysis, regenerating NAD⁺ to allow glycolysis to continue. The overall equation is:
Lactic acid fermentation.
- Begins with glycolysis
- 2 pyruvate ultimately yields 2 lactate
- Pyruvate acts as an electron acceptor, allowing NADH to be oxidised back into NAD+.
- Other form of lactate is lactic acid
Krebs Cycle
The Krebs cycle (also called the citric acid cycle or TCA cycle) is a series of enzyme-catalyzed reactions in the mitochondrial matrix that generate energy through the oxidation of acetyl-CoA. It produces NADH, FADH₂, ATP (or GTP), and CO₂, which are essential for cellular respiration and ATP production in the electron transport chain.
