Flashcards on Energy Production and Metabolism

Practice flashcards covering key terms and concepts related to energy production, metabolism, and mitochondrial function, based on lecture notes.

Metabolism

The sum of all biochemical reactions in the body, classically divided into catabolism and anabolism.

Catabolism

Biochemical reactions that involve the breakdown of complex macromolecules into smaller units, often releasing energy stored in ATP.

Anabolism

Biochemical reactions that utilize ATP to synthesize complex molecules from simpler precursors, supporting cell growth, differentiation, and tissue repair.

First Law of Thermodynamics

States that energy cannot be created or destroyed; it can only be transferred or transformed.

Mitochondria

The main site of ATP production, involved in oxidative phosphorylation (OXPHOS), TCA cycle, β-oxidation of fatty acids, Ca2+ buffering, signaling, and apoptosis.

Endosymbiotic Theory

Proposes that mitochondria originated from a symbiotic relationship between a primitive eukaryotic host cell and an ancestral α-proteobacterium, with the bacterium providing ATP and the host offering protection.

Mitochondrial Outer Membrane

The outermost layer of the mitochondrion.

Mitochondrial Inner Membrane

The inner layer of the mitochondrion, folded into cristae, which serves as a barrier to protons to maintain a proton gradient.

Intermembrane Space

The region between the inner and outer mitochondrial membranes, where a proton gradient is maintained with a higher concentration of protons.

Cristae

The folds of the inner mitochondrial membrane.

Matrix (Mitochondrial)

The innermost compartment of the mitochondrion, where the Krebs cycle and oxidative decarboxylation of pyruvate occur.

ATP Synthase

An enzyme present in the inner mitochondrial membrane that produces ATP through the flow of protons across the membrane, causing rotation of its subunits.

Glycolysis

The process in the cytoplasm where glucose is broken down into two molecules of pyruvate, generating a net gain of 2 ATP and 2 NADH.

NADH

A coenzyme that carries high-energy electrons (along with FADH2) to the electron transport chain for further ATP generation.

Pyruvate Dehydrogenase Complex

An enzyme complex in the mitochondrial matrix that converts pyruvate into acetyl-CoA through oxidative decarboxylation, also producing NADH and CO₂.

Acetyl-CoA

A molecule formed from pyruvate, which then enters the Krebs cycle for further energy production.

Krebs Cycle (Citric Acid Cycle)

A metabolic cycle in the mitochondrial matrix where acetyl-CoA joins oxaloacetate, producing 1 ATP, 3 NADH, and 1 FADH2 per turn.

FADH2

A coenzyme that carries high-energy electrons (along with NADH) to the inner mitochondrial membrane to participate in the electron transport chain.

Electron Transport Chain (ETC)

Comprises four protein complexes embedded in the inner mitochondrial membrane, where electrons are passed through redox centers, pumping protons and ultimately forming water with oxygen, leading to ATP production.

Proton Gradient

A difference in positively charged proton (H⁺) concentration across the inner mitochondrial membrane, with a higher concentration in the intermembrane space, essential for ATP synthase function.

Oxygen (in ATP Production)

Acts as the final electron acceptor at Complex IV in the ETC, forming water; its absence halts ATP production.

Aerobic Respiration

The process of energy generation that requires oxygen, involving glycolysis, the Krebs cycle, and the electron transport chain.

Anaerobic Respiration

The process of energy generation that occurs with no oxygen present, primarily involving anaerobic glycolysis and fermentation.

Anaerobic Glycolysis

Converts glucose into a small amount of ATP (2 net ATP) in the cytoplasm, without involvement of the Krebs cycle or the electron transport chain, occurring in the absence of oxygen.

Fermentation

A process during anaerobic respiration that recycles NADH back into NAD+ by converting pyruvate to lactate, allowing glycolysis to continue and produce ATP.

Lactate

An output of fermentation in anaerobic glycolysis; increased blood levels are routinely measured and can indicate impaired aerobic respiration.

Cytosol (Metabolic Function)

The cellular compartment that is the site of glycolysis, pentose phosphate pathway, and parts of lipid and amino acid metabolism, including fatty acid synthesis.

Nucleus (Metabolic Function)

Essential for nucleotide metabolism, RNA processing, and histone modification, which are all metabolically regulated processes.

Endoplasmic Reticulum (ER) (Metabolic Function)

A cellular compartment key in lipid and steroid synthesis, and in protein folding with post-translational modifications requiring energy.

Peroxisomes (Metabolic Function)

Organelles that contribute to metabolism through fatty acid oxidation.

Lysosomes (Metabolic Function)

Organelles that contribute to metabolism through macromolecule degradation, essential for cellular recycling and energy balance.