Chapter 5: Ground Rules of Metabolism Flashcards

Vocabulary practice flashcards covering fundamental metabolism concepts, enzyme mechanisms, energy laws, membrane structure, and transport pathways.

Alcohol dehydrogenase

A liver enzyme that breaks down ethanol, the overload of which can lead to fat accumulation and liver damage.

Energy

The capacity to do work.

First law of thermodynamics

The law stating that energy is neither created nor destroyed, but can be transferred from one form to another.

Second law of thermodynamics

The law stating that entropy increases spontaneously in any isolated system.

Entropy

A measure of the dispersal of energy in a system.

Reactant

An atom, ion, or molecule that enters a chemical reaction.

Product

An atom, ion, or molecule remaining at the end of a chemical reaction.

Endergonic reaction

A chemical reaction that requires a net input of energy to proceed.

Exergonic reaction

A chemical reaction that ends with a net release of energy.

Activation energy

The minimum amount of energy needed to get a chemical reaction started.

Catalysis

A process where an enzyme accelerates a specific reaction rate without being consumed or altered by the reaction.

What do arteries do?

Transport blood around your body

Substrate

A specific reactant molecule acted upon by an enzyme.

Active site

A pocket in an enzyme where catalysis occurs and substrates bind.

Induced-fit model

A mechanism of enzyme-substrate interaction where binding induces a structural change in the enzyme that brings on the transition state.

Metabolism

All chemical activities by which cells acquire and use energy.

Metabolic pathway

Any series of enzyme-mediated chemical reactions in a cell that builds, rearranges, or breaks down organic substances.

Linear pathway

A metabolic pathway that runs straight from reactant to product.

Cyclic pathway

A metabolic pathway in which the last step regenerates a starting reactant for the first step.

Feedback inhibition

A regulatory mechanism in which the end product of a pathway decreases or stops the activity of an enzyme in that pathway.

Allosteric regulation

Regulation of enzyme activity caused by the binding of a regulatory molecule outside of the active site.

Oxidation-reduction reaction

A chemical reaction involving electron transfer, where the molecule giving up electrons is oxidized and the accepting molecule is reduced.

Electron transfer chain

A series of membrane-bound enzymes and molecules that accept and pass electrons sequentially to release energy.

Cofactor

An atom or non-protein molecule required for an enzyme to function properly.

Coenzyme

An organic cofactor, such as a vitamin derivative, that assists enzyme activity.

ATP (Adenosine triphosphate)

A nucleotide composed of adenine, ribose, and three phosphate groups that serves as the primary energy carrier in cells.

Phosphorylation

A chemical reaction involving the transfer of a phosphate group from one molecule to another.

Fluid mosaic model

A model describing cell membrane structure as a two-dimensional fluid consisting of a mosaic mixture of phospholipids, steroids, and proteins.

Peripheral membrane protein

A protein temporarily attached to the inner or outer surface of a cell membrane.

Integral membrane protein

A protein permanently embedded within or attached across a cell membrane lipid bilayer.

Diffusion

The net movement of molecules or ions down a concentration gradient.

Selective permeability

The ability of a cell membrane to control which substances can pass through it and in what amounts.

Osmosis

The diffusion of water across a selectively permeable membrane down its concentration gradient.

Tonicity

The relative solute concentrations of two fluids separated by a selectively permeable membrane.

Isotonic solution

A solution that has the same solute concentration as the fluid inside a cell.

Hypotonic solution

A solution that has a lower solute concentration than the fluid inside a cell, causing water to diffuse into the cell.

Hypertonic solution

A solution that has a higher solute concentration than the fluid inside a cell, causing water to diffuse out of the cell.

Turgor

The pressure exerted by a volume of fluid against a cell wall, membrane, or surrounding structure.

Osmotic pressure

The amount of turgor required to prevent water from diffusing into a hypertonic solution.

Passive transport

A membrane transport mechanism driven entirely by a concentration gradient without requiring energy input.

Facilitated diffusion

A specific type of passive transport where a transport protein helps a solute move across a membrane down its gradient.

Active transport

A membrane transport mechanism where a transport protein uses energy to move a solute against its concentration gradient.

Sodium-potassium pump

An active transport protein that pumps sodium ions ($\text{Na}^+$) out of the cytoplasm and potassium ions ($\text{K}^+$) into the cell using energy from ATP.

Exocytosis

The process by which a vesicle fuses with the plasma membrane, releasing its contents into the extracellular fluid.

Endocytosis

The process by which a cell takes in extracellular substances by forming a vesicle from its plasma membrane.

Pinocytosis

An endocytic pathway in which a cell traps extracellular fluid and suspended particles in a vesicle.

Receptor-mediated endocytosis

An endocytic pathway in which target molecules bind to specific cell-surface receptors, triggering vesicle formation.

Phagocytosis

An endocytic process in which a cell uses pseudopods to engulf large target particles such as microbes or cellular debris.