chapter 7 – cellular respiration. pathways i. glycolysis and fermentation a.harvesting chemical...
TRANSCRIPT
Chapter 7 – Cellular Respiration
Pathways
I. Glycolysis and Fermentation
A. Harvesting Chemical Energy1. Glycolysis – biochemical pathway in which glucose is converted to two molecules of pyruvic acid; 6-C Two 3-C
* Occurs in the cytoplasm.
Steps:1. Glucose + 2 phosphates + 2 ATP Fructose 1,6 biphosphate P-C-C-C-C-C-C-P
2. Fructose 1,6 biphosphate splits into two PGAL (G3P); P-C-C-C C-C-C-P
3. Two PGAL + 2 NAD+ 2 biphosphoglycerate P-C-C-C-P P-C-C-C-P
4. 2 biphosphoglycerate + 4 ADP 2 molecules pyruvic acid + 4 ATP C-C-C C-C-C
Pyruvic Acid (Pyruvate)
B. Energy Yield – Glycolysis 1) * 2 ATP were used
* 4 ATP were produced * Net gain of 2 ATP * 2 NADH - will be used in the electron
transport chain
2) Efficiency = Energy required Energy released
= 2 x 12 kcal x 100% 686 kcal
= 3.5 %
Glycolysis
C. Anaerobic Respiration – pathway which occurs without oxygen.
* yeast and bacteria cells.* cells that become deprived of oxygen.* occurs in the cytoplasm.
Anaerobic Respiration
1. Fermentation – converting pyruvic acid into other compounds without oxygen.
Types: a. Lactic Acid Fermentation Pyruvic Acid + 2 H+ Lactic Acid 3-C
1) Importances * Foods – i.e. yogurt; cheese
* Fatigued muscle cells
b. Alcoholic Fermentation Pyruvic Acid loses CO2 Acetylaldehyde 2-C
Acetylaldehyde + 2 H+ Ethyl Alcohol 2-C
1) Importances* Bread products* Beer, wine, and spirits industry
Anaerobic Respiration
II. Aerobic Respiration – producing energy with oxygen.
A. Occurs in the mitochondrion.1. Outer membrane2. Cristae – inner folds of membrane3. Matrix – space inside the inner membrane; contains enzymes.
B. Steps:1. Pyruvic acid + coenzyme A
Acetyl CoA + CO2
* 2-C
* occurs in the matrix * Produces 2 NADH – will be used in the electron transport chain
2. Kreb’s Cycle – biochemical pathway that breaks down Acetyl CoA into CO2, H+, and
ATP.
Steps:1. Acetyl CoA + oxaloacetic acid Citric acid 6-C
2. Citric acid releases CO2 + H+ 5-C compound
3. 5-C compound releases CO2 + H+ 4-C
compound.
4. 4-C compound releases H + New 4-C compound
5. 4-C Compound releases H+ Oxaloacetic acid; Kreb’s Cycle continues.
Net Yield:* 2ATP* 6 NADH used in the electron* 2 FADH2 transport chain
Video – Kreb’s Cycle
Video – Kreb’s Cycle
3. Electron Transport Chaina. Occurs on the cristae.b. Uses the NADH and FADH2 from
glycolysis, the conversion of pyruvic acid acetyl CoA, and the Kreb’s Cycle
c. Steps:1) High energy electrons are passed along a series of molecules.2) As the electrons move from molecule to molecule, the energy they lose is used to pump protons (H+) from the matrix to the inner membrane.
3) A concentration gradient of H+ drives the synthesis of ATP by chemiosmosis: ADP + P + ATP Synthase ATP
4) Oxygen continues to accept electrons. This allows the ETC to continue:
O2 + 4 e- + 4 H+ 2 H2O
III. Summary of Aerobic Respiration C6H12O6 + 6 O2 6 CO2 + 6 H2O + ATP(Energy)
A. Energy Yield1) Glycolysis – 2 ATP2) Kreb’s Cycle – 2 ATP3) Electron Transport Chain – 34 ATP Total – 38 ATP
B. Efficiency38 x 12 kcal x 100% = 66%
686 kcal
Video – Electron Transport Chain
Video – Cellular Respiration
The End