C1.2 - Cell respiration

ATP as the molecule that distributes energy within cells

ATP (adenosine triphosphate) is a nucleotide that stores and transfers energy within cells, making it suitable as the cell's energy currency due to its ability to release energy quickly through hydrolysis.

Life processes within cells that ATP supplies with energy

ATP provides energy for active transport, synthesis of macromolecules (anabolic reactions), and movement of the cell or cellular components like chromosomes.

Energy transfers during interconversions between ATP and ADP

Energy is released when ATP is hydrolyzed to ADP and phosphate; synthesizing ATP from ADP and phosphate requires energy input.

Cell respiration as a system for producing ATP within the cell using energy released from carbon compounds

Cell respiration breaks down carbon compounds like glucose and fatty acids to release energy used to produce ATP; this is distinct from gas exchange.

Differences between anaerobic and aerobic cell respiration in humans

Aerobic respiration requires oxygen and occurs in mitochondria, yielding more ATP and producing CO₂ and H₂O; anaerobic respiration does not require oxygen, occurs in the cytoplasm, yields less ATP, and produces lactate.

Variables affecting the rate of cell respiration

Factors such as temperature, substrate concentration, and oxygen availability affect cellular respiration rate and can be measured experimentally.

Role of NAD as a carrier of hydrogen and oxidation by removal of hydrogen during cell respiration

NAD is reduced when it accepts hydrogen; removal of hydrogen (dehydrogenation) from substrates is oxidation, and redox reactions involve both oxidation and reduction.

Conversion of glucose to pyruvate by stepwise reactions in glycolysis with a net yield of ATP and reduced NAD

Glycolysis involves phosphorylation, lysis, oxidation, and ATP formation; each step is catalyzed by a specific enzyme and results in pyruvate, ATP, and reduced NAD.

Conversion of pyruvate to lactate as a means of regenerating NAD in anaerobic cell respiration

Pyruvate is converted to lactate to regenerate NAD, allowing glycolysis to continue and producing a net gain of 2 ATP per glucose molecule.

Anaerobic cell respiration in yeast and its use in brewing and baking

In yeast, anaerobic respiration results in ethanol and carbon dioxide; this process is used in brewing and causes dough to rise in baking.

Oxidation and decarboxylation of pyruvate as a link reaction in aerobic cell respiration

Pyruvate is oxidized and decarboxylated to produce acetyl groups, which are carried by coenzyme A to enter the Krebs cycle.

Oxidation and decarboxylation of acetyl groups in the Krebs cycle with a yield of ATP and reduced NAD

Acetyl groups join with oxaloacetate to form citrate; through a series of steps, oxaloacetate is regenerated with four oxidations (dehydrogenations) and two decarboxylations, producing ATP and reduced NAD.

Transfer of energy by reduced NAD to the electron transport chain in the mitochondrion

Reduced NAD from glycolysis, the link reaction, and the Krebs cycle donates electrons to the electron transport chain, transferring energy and regenerating NAD.

Generation of a proton gradient by flow of electrons along the electron transport chain

Electrons pass through the transport chain, releasing energy that pumps protons into the intermembrane space, generating a proton gradient.

Chemiosmosis and the synthesis of ATP in the mitochondrion

ATP synthase uses the energy released as protons flow back into the mitochondrial matrix to phosphorylate ADP into ATP.

Role of oxygen as terminal electron acceptor in aerobic cell respiration

Oxygen accepts electrons and protons at the end of the electron transport chain, forming water and allowing the chain to continue functioning.

Differences between lipids and carbohydrates as respiratory substrates

Lipids yield more energy per gram due to their higher hydrogen and carbon content; carbohydrates are required for glycolysis and anaerobic respiration, while fatty acids are broken down into 2C acetyl groups for aerobic respiration.