Metabolism and Nutrition - Chapter 25 (Key Terms)

Vocabulary flashcards covering key terms and concepts from metabolism and nutrition discussed in the lecture notes.

Metabolism

The total of all chemical reactions in the body, balancing catabolic and anabolic processes to harvest energy from nutrients for growth, repair, and normal function.

Homeostasis

Maintenance of stable internal conditions within the body.

Catabolic reactions

Reactions that break down complex molecules into simpler ones, releasing energy.

Anabolic reactions

Reactions that build complex molecules from smaller units, requiring energy.

ATP (adenosine triphosphate)

The primary energy currency of the cell; couples energy-releasing reactions to energy-requiring ones.

Substrate-level phosphorylation

Direct transfer of a high-energy phosphate group from a substrate to ADP to form ATP.

Oxidative phosphorylation

ATP production via electron transport and chemiosmosis; energy from NADH/FADH2 is used to drive ATP synthesis with oxygen as the final acceptor.

Glycolysis

Cytoplasmic pathway that oxidizes glucose to pyruvate, producing ATP and NADH.

Glucose

A six-carbon sugar that is the primary substrate for glycolysis and cellular respiration.

Pyruvic acid (pyruvate)

End product of glycolysis; can be converted to acetyl-CoA under aerobic conditions or to lactic acid under anaerobic conditions.

Glucose-6-phosphate

Phosphorylated glucose that is trapped inside the cell and cannot exit.

GLUT transporter

Facilitated diffusion transporter that moves glucose into cells.

Acetyl-CoA

Two-carbon acetyl group bound to CoA; entry molecule for the Krebs cycle formed from pyruvate oxidation.

Pyruvate dehydrogenase

Enzyme complex that converts pyruvate to acetyl-CoA, producing CO2 and NADH.

Krebs cycle (Citric acid cycle)

Occurs in the mitochondrial matrix; a series of redox reactions that produce CO2, NADH, FADH2, and a small amount of ATP.

NAD+/NADH

Nicotinamide adenine dinucleotide; accepts electrons to become NADH during metabolism.

FAD/FADH2

Flavin adenine dinucleotide; accepts electrons to become FADH2 during metabolism.

Electron Transport Chain (ETC)

Series of protein carriers in the inner mitochondrial membrane that transfer electrons, pump protons, and drive ATP synthesis.

Chemiosmosis

Movement of protons across a membrane to drive ATP production via ATP synthase.

Oxygen as final electron acceptor

In the ETC, O2 accepts electrons at the end of the chain and forms water.

Cellular respiration

Complete oxidation of glucose to CO2 and H2O, yielding ATP.

Glycolysis Step 1

Glucose is oxidized to two pyruvate molecules in the cytoplasm.

Anaerobic vs aerobic fate of pyruvate

Under anaerobic conditions, pyruvate is reduced to lactate; under aerobic conditions, it is converted to acetyl-CoA for entry into the Krebs cycle.

Krebs cycle location

Mitochondrial matrix.

ETC location

Inner mitochondrial membrane.

Glycolysis location

Cytoplasm.

Glycogen synthesis and triglyceride synthesis

Fates of glucose beyond immediate energy production; glucose can be stored as glycogen or converted to fatty acids and triglycerides.

CO2 production in metabolism

CO2 is produced during pyruvate oxidation and the Krebs cycle.