Tuesday, December 8, 2009

Chapter 9: Cellular Respiration: Harvesting Chemical Energy


Q: What is the basic balanced equation for cellular respiration?

A: C6H12O6 + 6 02 -------> 6 O2 + 6 H20 + Energy(ATP + heat)

Q: What are the three metabolic stages of cellular respiration?

A: Glycolysis, the citric acid cycle, and Oxidative
phosphoryation: electron transport and chemiosmosis

Q: What are the two electron carriers?

A: NADH+ and FADH2


1. Catabolic pathways yield energy by oxidizing organic fuels.

2. Glycolysis harvests chemical energy by oxidizing glucose to pyruvate.

3. The citric acid cycle completes the energy-yie
lding oxidation of organic molecules.

4. During oxidative phosphorylation, chemiosmosis couples electron transport to ATP synthesis.

5. Fermentation and anaerobic respiration enable cells to produce ATP without the use of oxygen.



This diagram shows the whole Cellular Respiration. It also shows when each ATP is produced, and shows that Glycolysis occurs in the cytoplasm. Then, in Mitochondria, the Krebs Cycle and Electron Transport System occur. The total ATP that can be produced from Cellular Respiration would be 36-38.




Cellular respiration allows organisms to use (release) energy stored in the chemical bonds of glucose(C6H12O6). The energy in glucose is used to produce ATP. Cells use ATP to supply their energy needs. Cellular respiration is therefore a process in which the energy in glucose is transferred to ATP. In respiration, glucose is oxidized and thus releases energy. Oxygen is reduced to form water. Then, the carbon atoms of the sugar molecule are released as carbon dioxide (CO2). The complete breakdown of glucose to carbon dioxide and water requires two major steps: 1: glycolysis and 2: aerobic respiration. Glycolysis produces two ATP and thirty-four more ATP are produced by aerobic pathways if oxygen is present. In the absence of oxygen, fermentation reactions produce alcohol or lactic acid but no additional ATP.


Fermentation: a partial degradation of sugars that occurs without the use of oxygen.

Oxidation-reduction (Redox) reactions: transfers of one or more electrons from one reactant to another.

Acetyl CoA: Acetyl coenzyme A; the entry compound for the citric acid cycle in cellular respiration, formed from a fragment of pyruvate attached to a coenzyme.

NAD+: Nicotinamide adenine dinucleotide, a coenzyme that can accept an electron and acts as an electron carrier in the electron transport chain.

Oxidative phosphorylation: The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration.

Substrate-level phosphorylation: The formation of ATP by an enzyme directly transferring a phosphate group to ADP from an intermediate substrate in catabolism.

Cytochromes: proteins that are mostly the remaining electron carriers between ubiquinone and oxygen.

ATP(adenosine triphosphate): an adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells.

ATP synthase: the enzyme that actually makes ATP from ADP and inorganic phosphate.

Chemiosmosis: the process in which energy stored in the form of a hydrogen ion gradient across a membrane is used to drive cellular work such as the synthesis of ATP



No comments:

Post a Comment