Cell Membrane and Enzyme Activity Review

A set of vocabulary flashcards covering cell membrane composition, tonicity, and the mechanisms and factors influencing enzyme activity.

Phospholipid bilayer

The structure of a cell membrane consisting of two layers of phospholipids with hydrophilic heads on the outside and hydrophobic tails on the middle.

Hydrophilic heads

The portion of the phospholipid located on the outside of the cell membrane bi-layer.

Hydrophobic tails

The portion of the phospholipid located on the inside of the cell membrane bi-layer.

Integral (intrinsic) proteins

Proteins that are embedded within the cell membrane structure.

Peripheral (extrinsic) proteins

Proteins that are located on the surface of the cell membrane.

Cholesterol

A component embedded within the membrane that helps provide support and regulate substances.

Hypotonic

A type of solution that, when compared to cell cytoplasm, may cause the movement of water into the cell.

Osmosis

The movement of water across a membrane, such as from a nutrient solution to a cell.

Fluid Mosaic

A model used to describe the review of membrane structure, featuring various proteins and phospholipids.

Aquaporin

A specific type of transport protein located in the phospholipid bilayer.

Enzymes

Biological catalysts that speed up chemical reactions in cells without being used up.

Active site

The specific area on an enzyme, determined by its complex tertiary structure, to which substrates bind.

Lock-and-key model

An enzyme model characterized by a rigid active site and a perfect fit with a highly specific substrate.

Induced-fit model

An enzyme model where the active site is less rigid and changes shape slightly when a substrate enters to accommodate its shape and stress its bonds.

Activation energy

The minimum required energy to start a reaction; enzymes catalyze reactions by lowering this threshold.

Denatured

The state of an enzyme when it loses its functional shape due to high temperature or pH deviation, preventing it from binding with a substrate.

Optimum temperature

The specific temperature range in which enzymes are most active and collisions between molecules are maximized.

Saturation

The point at which further increases in substrate concentration do not increase the rate of reaction because all active sites are occupied.

Enzyme inhibitor

A substance that blocks the active site or changes its shape so that the substrate can no longer fit.

Cofactors

Small inorganic substances, such as $Zn$, $Fe$, or $Mg$ ions, that change the shape or charge of an active site to make it more effective.

Coenzymes

Non-protein organic substances that play a significant role in metabolism by assisting enzyme function.

Tertiary structure

The complex folding of a polypeptide that determines the shape and chemistry of an enzyme's active site.