Topic 5 - metabolism

Flashcards covering key vocabulary related to energy, metabolism, chemical reactions, ATP, enzymes, cellular respiration (aerobic and anaerobic), and photosynthesis based on the lecture notes.

Energy

The ability to do work.

Potential energy

Stored energy.

Kinetic energy

Movement energy.

Energy transformation

The conversion of kinetic energy to potential energy or vice versa.

Chemical reactions

A process in which one or more substances, the reactants, are converted to one or more different substances, the products; bonds are broken and/or formed, and energy is transformed.

Reactants

Substances that are converted during a chemical reaction.

Products

New substances formed from reactants during a chemical reaction.

Coefficient

Indicates the number of a molecule in a chemical reaction.

Subscript

Indicates the number of an atom in a molecule.

Activation energy

The energy required to start a reaction.

Metabolism

All the chemical reactions in a cell.

Metabolic pathway

A series of chemical reactions that modifies a molecule step-by-step.

Anabolic pathway

Small molecules are built into large ones, requiring energy.

Catabolic pathway

Large molecules are broken down into small ones, releasing energy.

ATP (Adenosine triphosphate)

The most commonly used primary energy molecule of the cell; energy is released when the third phosphate group is broken off.

Cellular respiration

The primary way cells add a third phosphate to ADP to create ATP, and a catabolic reaction where glucose is broken down to release energy.

Photosynthesis

An anabolic reaction occurring in autotrophs that captures energy in light and stores it in sugars.

Enzymes

Biological catalysts, usually proteins, that lower the activation energy of chemical reactions.

Catalyst

Lowers the energy required for a chemical reaction to take place (activation energy).

Substrates

The reactants that attach to the enzyme.

Aerobic respiration

Cellular respiration process that uses oxygen to break apart glucose and capture the released energy in ATP.

Glycolysis

The first stage of aerobic respiration that breaks down glucose into two smaller molecules and generates some ATP and NADH; occurs in the cytoplasm.

Citric acid cycle (Krebs cycle)

The second stage of aerobic respiration that further breaks down molecules, generating high-energy electrons (NADH and FADH2) and releasing carbons as carbon dioxide; occurs in the mitochondria.

Oxidative phosphorylation

The third stage of aerobic respiration that uses high-energy electrons delivered by electron carriers to power the formation of ATP using ATP synthase; oxygen is needed for this process, acting as an electron acceptor.

Electron carriers

Molecules like NADH, FADH2, and NADPH that carry high-energy electrons from one reaction to another.

NADH

Nicotinamide adenine dinucleotide in its reduced, electron-carrying form; delivers electrons to the electron transport chain.

FADH2

Flavin adenine dinucleotide in its reduced, electron-carrying form; delivers electrons to the electron transport chain.

NADPH

Nicotinamide adenine dinucleotide phosphate in its reduced, electron-carrying form; used in photosynthesis.

Anaerobic respiration

Production of ATP without oxygen, typically through fermentation.

Fermentation

A process that keeps glycolysis running by replenishing NAD+ from NADH when there is not enough oxygen, allowing glycolysis to produce ATP.

Autotrophs

Organisms like plants, algae, and cyanobacteria that perform photosynthesis to capture energy in light and store it in sugars.

Chloroplast

The organelle within a cell where photosynthesis occurs.

Photosynthetic pigments

Molecules in plants that absorb light at certain wavelengths.

Chlorophyll

A photosynthetic pigment that absorbs light energy of blue and red light and reflects green light.

Photosystem

A structure within which chlorophyll sits, absorbing light energy during photosynthesis.

Light-dependent reactions

The first stage of photosynthesis that occurs only in the presence of light, using sunlight energy to make ATP and NADPH; involves water donating electrons to a photosystem.

Light-independent reactions (Calvin cycle)

The second stage of photosynthesis that occurs in light or dark, using ATP and NADPH to make glucose from carbon dioxide; takes place in the stroma of the chloroplast.

Carbon cycle

The natural process involving the exchange of carbon between the atmosphere, oceans, terrestrial biosphere, and sediments, with key roles played by photosynthesis and cellular respiration.