Cell Biology Metabolism and Energy Quiz

Metabolism refers to all chemical reactions occurring within a cell.
Catabolism involves breaking down molecules, releasing energy for use in other reactions.
Anabolism is the synthesis of complex molecules from simpler ones, requiring energy input.

Three major types of work performed by cells:
- Chemical work: Involves anabolic processes.
- Transport work: Involves nutrient uptake.
- Mechanical work: Includes movement, such as flagellum rotation.

Standard Free Energy Change (ΔG) is measured under standard conditions: pH 7, 25°C, 1 atm pressure.
Exergonic reactions have negative ΔG, releasing energy that can be harnessed for cellular work, such as ATP synthesis via phosphorylation.
Endergonic reactions, characterized by positive ΔG, require energy input and often hydrolyze ATP to release energy.

Adenosine Triphosphate (ATP) is a high-energy molecule synthesized during exergonic reactions.
Orthophosphate (Pi) is the phosphate group added to ADP to form ATP.

Activation energy is the energy necessary to break chemical bonds, which can be lowered by catalysts like enzymes.

Oxidation-Reduction (Redox) reactions are crucial for energy conservation, transferring electrons from donors to acceptors.
Oxidation involves electron loss, while reduction signifies electron gain; remember OIL RIG (Oxidation Is Loss, Reduction Is Gain).

A conjugate redox pair consists of an electron acceptor and donor.
Standard Reduction Potential (E'0) indicates the tendency to donate electrons; more negative E'0 indicates a stronger donor.
Redox Tower ranks couples based on E'0, with the most negative at the top and the most positive at the bottom.

Electron carriers oscillate between reduced (electron-carrying) and oxidized (after transferring electrons) forms.
Carriers are arranged in sequence based on their standard reduction potential in a process that maximizes energy release.

Nicotinamide Adenine Dinucleotide (NAD+/NADH): Carries electrons and protons.
Nicotinamide Adenine Dinucleotide Phosphate (NADP+/NADPH): Accepts 2 electrons and 1 proton.
Flavin Adenine Dinucleotide (FAD/FADH) and Flavin Mononucleotide (FMN/FMNH): Carry 2 electrons and 2 protons, found in flavoproteins.
Coenzyme Q (CoQ/Ubiquinone): Carries 2 electrons and 2 protons.
Cytochromes: Contain iron to transfer 1 electron at a time.
Iron-Sulfur Proteins (Ferredoxin): Use non-heme iron to transfer 1 electron.

The electron transport chain transfers electrons from external initial donors to final acceptors, passing through carriers in an efficient membrane-embedded sequence.
Found in the cell membranes of bacteria and archaea, as well as in the mitochondrial membranes of eukaryotes.