Cell Respiration and Energy Transfer C1.2

ATP

Adenosine triphosphate, a ribonucleotide consisting of an adenine base and three phosphate groups attached to the central ribose sugar, serving as the 'energy currency' of the cell

Anabolic reactions

Biochemical reactions that use ATP to construct complex molecules from simpler subunits

Active transport

Process that requires ATP to move material against a concentration gradient

Vesicular transport

Process (endocytosis/exocytosis) requiring ATP to break and reform membranes

Anaerobic Respiration

Cellular respiration not requiring oxygen, starting with glycolysis and leading to fermentation

Aerobic Respiration

Cellular respiration requiring oxygen, involving glycolysis, the Krebs cycle, and the electron transport chain

Law of limiting factors

Principle stating that the factor in shortest supply determines the rate of a biochemical process

Respirometer

Device measuring an organism's aerobic respiration rate by monitoring oxygen consumption

NAD

Nicotinamide adenine dinucleotide, a hydrogen carrier reduced to form NADH during cell respiration

Redox Reactions

Chemical reactions involving the transfer of electrons, hydrogen, or oxygen, with one species being reduced and another oxidized

Hydrogen Carriers

Coenzymes like NAD and FAD that transport hydrogen atoms to the mitochondria for ATP synthesis via oxidative phosphorylation

Glycolysis

Stepwise breakdown of glucose into pyruvate in the cytosol, yielding ATP and reduced NAD

Phosphorylation

Glucose is phosphorylated by two molecules of ATP to form a hexose bisphosphate, making the molecule less stable and reactive, and preventing diffusion out of the cell.

Lysis

The hexose biphosphate (6C sugar) is split into two triose phosphates (3C sugars) during glycolysis.

Oxidation

Hydrogen atoms are removed from each of the 3C sugars to reduce NAD, producing two molecules of NADH in total.

ATP Formation

Some energy released from sugar intermediates is used to synthesize ATP, generating four molecules of ATP by substrate-level phosphorylation with a net gain of 2 ATP.

Conversion of pyruvate to lactate

A process in anaerobic cell respiration where pyruvate is converted into lactate to regenerate NAD.

Fermentation

The conversion of pyruvate into an alternative carbon compound to restore unloaded coenzyme needed for glycolysis in the absence of oxygen.

Anaerobic cell respiration in yeast

Fermentation in yeast results in the production of ethanol and carbon dioxide, with applications in brewing and baking.

Link Reaction

The stage in aerobic respiration that transports pyruvate into the mitochondria, involving decarboxylation and oxidation to form acetyl coenzyme A.

Krebs Cycle

The stage in aerobic respiration occurring in the mitochondria matrix, involving the breakdown of acetyl CoA to produce ATP, CO2, and hydrogen carriers.

Electron Transport Chain

The final stage of aerobic respiration located on the inner mitochondrial membrane, releasing energy from reduced hydrogen carriers to synthesize ATP.

Proton Motive Force

The oxidized hydrogen carriers release high-energy electrons and protons, creating an electrochemical gradient that drives ATP synthesis.

Chemiosmosis

The process where H+ ions move down their electrochemical gradient through ATP synthase, facilitating ATP synthesis.

Role of Oxygen

Oxygen acts as the terminal electron acceptor in the electron transport chain, preventing blockages and maintaining the hydrogen gradient.

Differences between lipids and carbohydrates as respiratory substrates

Carbohydrates are commonly used due to easier digestion and transport, while lipids serve as a long-term energy source, producing more energy per gram.