Membrane Structure and Transport, Energy and Metabolism, Enzymes

Vocabulary flashcards summarizing key concepts from the lecture on membrane structure, transport mechanisms, energy and metabolism, and enzymes.

Fluid Mosaic Model

A description of a membrane’s structure as diverse protein molecules suspended in a fluid phospholipid bilayer.

Selective Permeability

A property exhibited by the plasma membrane that allows it to regulate the passage of substances into and out of the cell.

Diffusion

The tendency of particles to spread out evenly in an available space.

Passive Transport

The diffusion of a substance across a biological membrane without the investment of energy.

Osmosis

The diffusion of water across a selectively permeable membrane.

Tonicity

A term describing the ability of a surrounding solution to cause a cell to gain or lose water.

Isotonic Solution

A solution with solute levels equal to those of the cell, resulting in no net movement of water.

Hypotonic Solution

A solution with lower solute levels than the cell, causing water to enter and the cell to swell or lyse.

Hypertonic Solution

A solution with higher solute levels than the cell, causing water to leave and the cell to shrink or shrivel.

Facilitated Diffusion

A type of passive transport where polar or charged substances move across a membrane with the help of specific transport proteins.

Aquaporin

A specific protein channel that enables the very rapid diffusion of water into and out of certain cells.

Active Transport

A process in which a cell must expend energy to move a solute against its concentration gradient.

Exocytosis

A mechanism used to export bulky molecules by packaging them in a vesicle that fuses with the plasma membrane.

Endocytosis

A process used to take in large molecules by packaging them within a vesicle that fuses with the membrane.

Phagocytosis

A type of endocytosis characterized by the engulfment of a particle by the cell.

Receptor-Mediated Endocytosis

A type of endocytosis that utilizes membrane receptors for specific solutes.

Kinetic Energy

The energy of motion.

Potential Energy

Energy that is stored in the location or structure of matter.

Chemical Energy

A form of potential energy stored in the chemical bonds of molecules.

Laws of Thermodynamics

Scientific laws stating that energy cannot be created or destroyed, only changed in form.

Exergonic Reaction

A chemical reaction that releases energy.

Endergonic Reaction

A chemical reaction that requires an input of energy.

Metabolism

The total of all chemical reactions performed by a cell.

ATP (Adenosine Triphosphate)

The main energy molecule that powers nearly all forms of cellular work.

Enzymes

Protein catalysts that speed up chemical reactions by decreasing the activation energy needed.

Activation Energy

The energy barrier that must be overcome for a chemical reaction to begin.

Substrate

The specific reactant that fits into an enzyme's active site.

Active Site

The specific region of an enzyme where a substrate binds.

Induced Fit

The process by which an enzyme changes shape slightly to fit the substrate more snugly.

Competitive Inhibitor

A substance that reduces an enzyme's productivity by competing with the substrate.

Noncompetitive Inhibitor

A substance that alters an enzyme's function by binding elsewhere.

Feedback Inhibition

A method of metabolic regulation where the product of a reaction inhibits an enzyme earlier in the pathway.