Chapter 7 - How Cells Harvest Energy Flashcards
The process utilized by cells to obtain energy from the oxidation of organic compounds accompanied by the consumption of oxygen (when available) and the release of carbon dioxide.
Respiration
An organism capable of synthesizing its own food from inorganic substances using light or chemical energy. (eg:)
Autotroph
eg: green plants, algae, certain bacteria
An organism that cannot manufacture its own food and instead obtains its food and energy by taking in organic substances, usually plant or animal matter.
(eg:)
Heterotroph
eg: animals, protozoans, fungi and most bacteria
The process of oxidizing food molecules, like glucose, to carbon dioxide and water is called…
The energy released…
The process occurs in two phases:
cellular respiration
…is trapped in the form of ATP for use by all the energy-consuming activities of the cell.
- glycolysis, the breakdown of glucose to pyruvic acid
- the oxidation of pyruvic acid to carbon dioxide and water
A chemical reaction that involves the removal of hydrogen from a molecule.
Dehydrogenation
A chemical reaction that involves the addition of hydrogen to a molecule.
Hydrogenation
Aerobic respiration
The process of producing cellular energy involving oxygen. Cells break down food in the mitochondria in a long, multistep process that produces roughly 36 ATP.
Anaerobic respiration
A form of respiration using electron acceptors other than oxygen. Although oxygen is not used as the final electron acceptor, the process still uses a respiratory electron transport chain. 2 ATP.
Fermentation
An anaerobic process in which energy is released. Enzymes convert sugars (glucose, etc.) to ethyl alcohol. Frees NAD so it can participate in future reactions of glycolysis.
Electron Transport Chain
A series of compounds that transfer electrons from electron donors to electron acceptors via redox reactions, and transfers protons (H+ ions) across a membrane. Creates an electrochemical proton gradient that drives ATP synthesis.
The final acceptor of electrons in the electron transport chain is…
Molecular oxygen
Examples of Electron Transport Chain
Sunlight in photosynthesis and oxidation of sugars in cellular respiration.
The addition of a phosphate (PO43−) group to a protein or other organic molecule. Turns many protein enzymes on and off, thereby altering their function and activity.
Phosphorylation
The metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+.
Glycolysis
An important enzyme that provides energy for the cell to use through the synthesis of ATP during chemiosmosis. It is formed from ADP and phosphate (Pi), and needs energy.
ATP synthase
The molecule that is left over when a cell breaks down glucose during glycolysis.
Pyruvate
Pyruvation then…
can either be further processed by entering the mitochondrion for aerobic respiration or changed into ethanol or lactic acid during fermentation.
Acetyl-CoA’s main function…
Acetyl-CoA oxidizes fatty acids. Creates NADH & starts the Krebs cycle.
An important molecule in metabolism, used in many biochemical reactions. Its main function is to convey the carbon atoms within the acetyl group to the citric acid cycle (Krebs cycle) to be oxidized for energy production.
Acetyl-CoA
A series of chemical reactions that generate energy through the oxidation of acetate derived from carbs, fats and proteins into CO2 and ATP.
Kreb’s Cycle
The movement of ions across a selectively permeable membrane, down their electrochemical gradient. Relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration or photosynthesis.
Chemiosmosis
cytochrome C
Transfers electrons between Complexes III (Coenzyme Q - Cyt C reductase) and IV (Cyt C oxidase) in electron transport chain
cytochrome oxidase complex
Complex IV. Catalyzes the final step in mitochondrial electron transfer chain, and is one of the major regulation sites for oxidative phosphorylation.
ethenol fermentation
Elements such as glucose, fructose, and sucrose are converted into cellular energy and thereby produce ethanol and carbon dioxide as metabolic waste products.
lactic acid fermenation
Glucose and other six-carbon sugars (also, disaccharides of six-carbon sugars, e.g. sucrose or lactose) are converted into cellular energy and the metabolite lactate.
bc1 complex
Links the electrons transfer from ubiquinol (or coenzyme Q) to cytochrome c and proton translocation across the inner mitochondrial membrane.
NADH dehydrogenase
Enzyme located on the inner mitochondrial membrane that catalyzes the oxidation by NAD+ of pyruvate to acetyl-CoA. Links glycosis and Krebs Cycle.
Steps of aerobic respiration
The first step in is glycolysis, the second is the citric acid cycle and the third is the electron transport system. The potential of NADH and FADH2 is converted to more ATP through an electron transport chain with oxygen as the “terminal electron acceptor”.
Glycolysis produces:
2 ATP
2NADH
X 2Pyruvate
Transition reaction produces:
2 NADH
X 2 CO2
X 2 Acetyl-CoA
Kreb’s Cycle yields:
6 NADH
2FADH2
2 ATP
Total ATP produced by electron transport & chemiosmosis
30-32 ATP
Pyruvate yields:
Acetyl CoA & CO2. CO2 is released and Acetyl-CoA —> NADH & the Krebs cycle.
Chemiosmosis
Hydrogen ions pass from the electron transport chain and diffuse from an area of high concentration to an area of lower proton concentration. The electrochemical concentration gradient of protons across the membrane can be harnessed to make ATP. Done by ATP synthase.
ATP Synthase
Uses the kinetic energy to phosphorylate ADP, making ATP. Used in Chemiosmosis.
Chemiosmosis yields:
NADH —–> 2 1/2 ATP
FADH2 —–> 1 1/2 ATP
Complex I
NADH —–> NAD+
NADH —> 2e- & 2H+
Complex II
FADH2 —–> FAD & 2H+
cytochrome Q (ubiquinone)
e- from Complex I & II
Complex III
e- from cytochrome Q
cytochrome C
e- from complex III
Complex IV
e- from cytochrome C
1/2O2 + 2H+ = H20
