Energy and Respiration Lecture Notes Flashcards

Comprehensive vocabulary flashcards covering aerobic and anaerobic respiration, mitochondria structure, respiratory substrates, and physiological adaptations.

Anabolic reactions

Metabolic reactions that build complex molecules from simpler ones, requiring energy, such as protein synthesis, glycogenesis, and DNA replication.

Adenosine triphosphate (ATP)

A phosphorylated nucleotide consisting of adenine, ribose, and three phosphate groups that acts as the universal energy currency in all organisms.

ATP Hydrolysis

The reversible reaction where ATP is broken down into ADP and Pi, releasing $30.5\,kJ\,mol^{-1}$ of energy.

Respiration

The process where organic molecules like glucose are broken down in stages to release energy used to synthesize ATP.

Glycolysis

The first stage of respiration occurring in the cytoplasm, involving the lysis of glucose into two molecules of pyruvate with a net gain of $2$ ATP.

Coenzymes

Non-protein complex organic substances, such as NAD, FAD, and Coenzyme A, that are required for an enzyme's activity.

NAD (Nicotinamide Adenine Dinucleotide)

A hydrogen carrier molecule in respiration composed of two linked nucleotides that accepts hydrogens to become reduced NAD (NADH).

Link Reaction

The second stage of aerobic respiration in the mitochondrial matrix where pyruvate is decarboxylated and dehydrogenated to form Acetyl Coenzyme A.

Krebs Cycle

The third stage of aerobic respiration, also known as the citric acid cycle, where Acetyl CoA combines with oxaloacetate ($4C$) to form citrate ($6C$).

Oxaloacetate

A $4C$ compound that combines with Acetyl CoA to start the Krebs cycle and is regenerated at the end of the cycle.

Oxidative Phosphorylation

The final stage of aerobic respiration in the inner mitochondrial membrane where ATP is synthesized using energy from the electron transport chain and chemiosmosis.

Electron transport chain (ETC)

A series of electron carrier proteins in the inner mitochondrial membrane that pass electrons, releasing energy to pump protons into the intermembrane space.

Chemiosmosis

The movement of protons down an electrochemical gradient through ATP synthase, providing the energy for ATP synthesis.

ATP Synthase

A transmembrane channel protein and enzyme that rotates as protons pass through it to catalyze the formation of ATP from ADP and Pi.

Substrate-level phosphorylation

The synthesis of ATP by the direct transfer of a phosphate group from one molecule to another, occurring during glycolysis and the Krebs cycle.

Mitochondrial Matrix

The site of the Link reaction and Krebs cycle, containing circular DNA, $70S$ ribosomes, and various enzymes.

Cristae

Foldings of the inner mitochondrial membrane that increase the surface area for the electron transport chain and ATP synthase.

Oxygen deficit

The volume difference between the ideal and real oxygen uptake during the initial stages of exercise when anaerobic respiration occurs.

Oxygen debt

The volume of oxygen required after exercise to metabolize accumulated lactate to $\text{CO}_2$ and water, and to reoxygenate hemoglobin.

Ethanol Pathway

The irreversible anaerobic pathway in yeast and plants where pyruvate is decarboxylated to ethanal and then reduced to ethanol.

Lactate Pathway

The reversible anaerobic pathway in animals where pyruvate is reduced to lactate by the enzyme lactate dehydrogenase.

Lactate dehydrogenase

The enzyme that catalyzes the conversion of pyruvate to lactate in anaerobic respiration and the conversion of lactate back to pyruvate in the liver.

Energy values of substrates

The amount of energy released per unit mass; Carbohydrates yield $15.8\,kJ\,g^{-1}$, Proteins yield $17.0\,kJ\,g^{-1}$, and Lipids yield $39.4\,kJ\,g^{-1}$.

Respiratory Quotient (RQ)

The ratio of the volume of carbon dioxide produced to the volume of oxygen consumed ($\text{RQ} = \text{Vol } \text{CO}_2 / \text{Vol } ext{O}_2$).

Respirometer

An apparatus used to measure the rate of oxygen uptake or calculate the RQ of small organisms by monitoring manometer fluid levels.

Soda lime

A chemical used in respirometers to absorb carbon dioxide so that changes in air volume reflect only oxygen consumption.

Redox indicators

Dyes like DCPIP or methylene blue that change from blue to colorless when reduced, used to measure the rate of respiration.

Aerenchyma

Specialized plant tissue with air spaces that allows oxygen to diffuse from aerial tissues to submerged roots, providing an adaptation for rice ($Oryza\,sativa$).

Alcohol dehydrogenase

An enzyme produced in high levels by rice roots to break down toxic alcohol produced during anaerobic respiration in flooded conditions.