Cellular Respiration Flashcards
Cellular Respiration (defn)
ATP-generation process.
C6H12O6 + 6O2 -> 6CO2 + 6H2O + Energy
Aerobic Respiration
occurs in the presence of oxygen; three steps:
- Glycolysis
- Krebs Cycle (TCA)
- Oxidative Phosphorlyation
Glycolysis
decomposition (lysis) of glucose into pyruvate/pyruvic acid; occurs in the cytosol.
1 Glucose -> 2 pyruvates + 2NADH + 2ATP (net 4 generated - 2 used)
Glycolysis (4 steps)
- 2 ATP added; first several steps require energy input.
- 2 NADH are produced; NADH is a coenzyme and forms when NAD+ combines with two energy-rich electrons and H+. NADH is an energy-rich molecule.
- 4 ATP is produced.
- 2 Pyruvates are formed.
Krebs Cycle
changes pyruvates from glycolysis; also known as tricarboxylic acid (TCA) cycle.
Krebs Cycle (2 steps)
- Pyruvate to acetyl CoA: pyruvate combines with coenzyme A (CoA) to produce acetyl CoA, 1 NADH, 1 CO2
Pyruvate -> Acetyl CoA + 1 NADH + 1 CO2
- Acetyl CoA to coenzymes: acetyl CoA combines with oxaloacetate to form citrate; produces 3 NADH, 1 FADH2, 1 H2O, 1 ATP
Acetyl CoA -> 3 NADH + 1 FADH2 + 1 H2O + 1 ATP
Oxidative Phosphorylation
extract ATP from NADH and FADH2 through the electron transport chain (ETC).
1 NADH -> 3 ATPs
1 FADH2 -> 2 ATPs
Total number of ATPs produced in Cellular Respiration
Glycolysis: 2 NADH, 2 ATP
Krebs: 2X(1 NADH + 3 NADH + 1 FADH2 + 1 ATP) = 8 NADH + 2 FADH2 + 2 ATP
Oxidative Phosphorylation:
10 NADH : 30 ATPs
2 FADH2 : 4 ATPs
4 ATPs
Total: 38 ATPs
(mitochondrial inefficiency results in ~30 ATPs)
Mitochondria
where Krebs cycle and oxidative phosphorylation occur
Mitochondria’s 4 areas
- Outer membrane: phospholipid bilayer
- Intermembrane area: where H+s accummulate
- Inner membrane: also phospholipid bilayer, consists of cristae/folds, where electron transport chain remove H+s from NADH and FADH2 and transports to the intermembrane area using proteins, ATP synthase also phosphorylates ADP to ATP.
- Matrix: fluid inside inner membrane, where Krebs and pyruvate -> acetyl CoA transformation occur.
Chemiosmosis
process of energy storage in the form of potentail energy created by the proton concentration gradient.
Chemiosmosis (5 steps)
- Krebs cycle produces NADH and FADH2
- Electrons are removed from NADH and FADH2
- H+ ions are transported from matrix to intermembrane space via protein complexes
- A pH and electrical gradient across the inner membrane is created and provides potential energy.
- ATP synthase generates ATP: this channel protein allows protons to flow from intermembrane to matrix; this proton movement generates energy for ATP synthase to phosphorylate ADP to ATP.
Two types of phosphorylation
- substrate level phosphorylation: ADP phosphorylated to ATP using energy from the substrate molecule containing the phosphate; occurs in glycolysis
- oxidative phosphorylation: ADP phosphorylated to ATP using energy from electrons of the ETC; energy generates H+ gradient which supplies energy to ATP synthase to generate ATP from ADP and a phosphate group.
Anaerobic Respiration (2 types)
cellular respiration in the absence of oxygen; occurs in cytosol; goal is to produce NAD+ to promote glycolysis.
- Alcohol fermentation: occurs in plants, fungi (yeasts), and bacteria
1) pyruvate -> acetaldehyde + CO2
2) Acetaldehyde + NADH -> NAD+ + EtOH - Lactic Acid fermentation: most lactate/lactic acid transported to liver where it is converted to glucose for use.
1) pyruvate + NADH -> NAD+ + lactic acid