Cell Biology-Chapter 14 notes

Mitochondria

Powerhouse of the cell, responsible for ATP production.

Energy Conversion

Proton gradients drive ATP synthesis via oxidative phosphorylation.

Electron Transport Chain (ETC)

Moves electrons through protein complexes, creating a proton gradient.

Proton Gradient & ATP Synthase

Proton movement powers ATP synthase, generating ATP.

Mitochondrial Structure

Matrix, inner membrane, outer membrane, intermembrane space.

Matrix

Contains enzymes for the Krebs cycle, mitochondrial DNA, and ribosomes

Inner Membrane

Houses ETC and ATP synthase, folded into cristae for increased surface area.

Outer Membrane

Contains porins for molecular exchange.

Intermembrane Space

Holds enzymes for nucleotide metabolism and apoptosis signaling.

Catabolism & Electron Carriers

NADH & FADH2 donate electrons to the ETC, powering proton pumping.

Complex I (NADH: Ubiquinone Oxidoreductase)

Transfers electrons from NADH to ubiquinone; pumps protons.

Complex II (Succinate: Ubiquinone Oxidoreductase)

Transfers electrons from succinate to ubiquinone; does not pump protons.

Complex III (Ubiquinol: Cytochrome c Oxidoreductase)

Transfers electrons to cytochrome c; pumps protons.

Complex IV (Cytochrome c Oxidase)

Transfers electrons to oxygen, forming water; pumps protons.

Proton Gradient & Electrochemical Force

Drives ATP synthesis and active transport of metabolites.

ATP Synthase Mechanism

Proton flow rotates central stalk, causing conformational changes that synthesize ATP.

Reversibility of ATP Synthase

Can hydrolyze ATP to restore the proton gradient if ATP levels are high.

Mitochondrial Transport Systems

Proton-powered symporters transport pyruvate, phosphate, and ADP/ATP exchange.

Ubiquinone & Cytochrome c

Mobile electron carriers connecting ETC complexes.

Cytochrome c Oxidase (Complex IV)

Transfers electrons to oxygen, completing ETC.

Uncoupling Proteins & Heat Generation

UCP-1 allows protons to bypass ATP synthase, generating heat (e.g., in brown fat).

Chloroplasts & Photosynthesis

light-dependent and light-independent reactions produce ATP and sugars

Photosystems & Light Absorption

Photosystem II & I use chlorophyll to absorb light energy.

Electron Flow in Photosynthesis

Photosystem II drives proton pumping; Photosystem I generates NADPH.

ATP & NADPH Production in Photosynthesis

Light reactions produce ATP and NADPH for the Calvin cycle.

Calvin Cycle & Carbon Fixation

Occurs in the stroma; Rubisco catalyzes CO2 fixation.

Energy Storage in Plants

Sugars & fats stored in chloroplasts for later metabolic use.

Mitochondria & Chloroplasts in Plant Cells

Work together to sustain energy metabolism.

Water-Splitting & Oxygen Release

Photosynthesis provides the oxygen we breathe.

Redox Potential in Energy Production

Electron transfer progressively lowers free energy while increasing redox potential.