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Photosynthesis: process in which light energy from the sun powers chemical processes that assemble organic molecules in plants
Chloroplasts: Site of photosynthesis.
Chlorophyll: Green pigment in leaves.
Autotrophs: organisms that produce all their own organic matter from inorganic matter. [Generally green plants, algae, & photosynthetic bacteria].
Heterotrophs: organisms incapable of producing organic matter from inorganic matter. [Generally animals, fungi, protozoans, and non-photosynthetic bacteria].
Cellular Respiration: Aerobic harvesting of chemical energy from fuel molecules.
Aerobic: Process that requires oxygen.
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP
Note: Redox (oxidation-reduction reaction) – reaction during respiration in which glucose is oxidized and oxygen is reduced.
- Oxidation: the loss of electrons Reduction: the gain of electron
- NAD (Nicotinamide Adenine Dinucleotide): An electron acceptor.
- NAD + H+ (electron) → NADH
- NAD is reduced by accepting a H electron which is then carried to the electron transport chain.
Electron Transport Chain
Electron Transport Chain: a series of molecules that collect and carry electrons in order to release energy used to make ATP. Locate in: mitochondria of all organisms, chloroplasts of green plants, the plasma membrane of prokaryotes.
Process of Electron Transport Chain
- Process of Electron Transport Chain
- 1. H is accepted from NADH.
- 2. H passes through the ETC until it is accepted by O at the end of the process.
- 3. ATP is made from ADP producing energy
Metabolic Pathway of Cellular Respiration
- Metabolic Pathway of Cellular Respiration
- Stage 1: Glycolysis
- Stage 2: Krebs Cycle
- Stage 3: Electron Transport Chain
- 1.During glycolysis, a 6C sugar – glucose – is split into two 3C molecules – pyruvic acid.
- 2.It costs 2 ATP molecules to activate this reaction.
- 3.NAD accepts electrons from the splitting glucose.
- 4.4 ATP are generated during glycolysis.
- Krebs Cycle
- 1.In preparation for the Krebs cycle, pyruvic acid (3C) is converted into acetic acid (2C) and bonded to Coenzyme A forming acetyl CoA.
- 2.Acetyl CoA (2C) is converted into CO2 (1C).
- 3.Each 2C molecule generates 1 ATP.
- 4.Each 2C molecule generates 3 NADH + 1 FADH2.
Cellular Respiration Blockers
- Cellular Respiration Blockers
- A.Cyanide & carbon monoxide (CO) block the transfer of electrons from the ETC to oxygen.
- B.Mitochondria can no longer convert food energy into ATP and the organism dies.
ATP Generation: Net total of ATP generated from 1 molecule of glucose is 36 ATP.
- Lipid Metabolism
- A.Carbohydrates are generally converted into lipids for storage.
- B.Lipids can be used for metabolism and serve better as energy storage.
- Protein Metabolism
- A. Protein molecules used in respiration, but only as a last resort.
- B Protein broken down into amino acid subunits with the removal of the amino group (otherwise converted into toxic ammonia)
- C. Protein metabolism results from starvation and conditions like anorexia nervosa.
Anaerobic Harvest of Food Energy
- Anaerobic Harvest of Food Energy
- A. Anaerobic: Process that does not require O2.
- B. Fermentation: breakdown of glucose to generate ATP using an electron acceptor other than oxygen
Fermentation in Muscle Cells
- Fermentation in Muscle Cells
- A.Glycolysis works anaerobically.
- B.A net total of two ATP are generated, (34 less than aerobic cellular respiration).
- C.Without O2, NADH deposits its H electrons with pyruvic acid – continuing the process.
- D. As pyruvic acid gains electrons, lactic acid (waste product) is produced.
- E.As lactic acid accumulates, soreness and muscle burning occurs.
- F.Lactic acid is carried in blood to the liver where it is aerobically converted into pyruvic acid.
Fermentation in Microorganisms
- Fermentation in Microorganisms
- A. Microorganisms (bacteria and fungi) also produce lactic acid.
- B. Commercially these microorganisms are used to produce cheese, sour cream, yogurt, soy sauce, pickles, olives, sausage, pepperoni, and salami.
- C. The anaerobic pathway yeast cells follow converts pyruvic acid into ethanol and CO2 instead of lactic acid
- In bread, CO2 causes yeast to rise.
- Wine contains ethanol while CO2 escapes.
- Champagne and beer contain both CO2 & ethanol.