Cell Membrane structure and Enzyme Activity Flashcards

A set of vocabulary flashcards covering cell membrane composition, tonicity, and the mechanics and factors affecting enzyme activity based on lecture notes.

Phospholipids

Components of the cell membrane organized into a bi-layer with hydrophilic heads on the outside and hydrophobic tails on the inside.

Hydrophilic heads

The part of a phospholipid that is attracted to water and faces the outside of the cell membrane bi-layer.

Hydrophobic tails

The part of a phospholipid that repels water and is positioned 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 membrane surface rather than being embedded within it.

Cholesterol

A substance embedded within the cell membrane that, along with proteins, contributes to its structure.

Hypotonic

A solution with a lower solute concentration compared to the cytoplasm of a cell, leading to the movement of water into the cell.

Hypertonic

A solution with a higher solute concentration compared to the cytoplasm of a cell.

Isotonic

A solution where the solute concentration is equal to that of the cytoplasm.

Osmosis

The movement of water across a membrane.

Fluid Mosaic Model

A conceptual model used to describe the arrangement of proteins, cholesterol, carbohydrates, and phospholipids in the cell membrane.

Enzymes

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

Active site

A specific area on the surface of an enzyme made of unique amino acids where substrate molecules bind.

Substrate

The specific chemical or reactant that an enzyme acts upon during a biochemical reaction.

Lock-and-key model

A model of enzyme action where the active site is rigid and the substrate provides a perfect fit, much like a key into a lock.

Induced-fit model

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

Activation energy

The minimum required energy to start a chemical reaction, which enzymes function to lower.

Denatured

The state of an enzyme when it loses its functional shape due to high temperatures or extreme pH, or when it can no longer catalyze a reaction.

Optimum temperature

The specific temperature range in which an enzyme operates most efficiently with the highest rate of reaction.

Pepsin

An enzyme that digests proteins specifically in the acidic juices of the stomach.

Alkaline phosphatase

An enzyme that catalyzes reactions in the alkaline environment of the bone.

Salivary amylase

An enzyme that digests carbohydrates in the mouth at a neutral pH.

Saturation

The point in a reaction where all active sites are occupied and further increases in substrate concentration do not increase the reaction rate.

Enzyme inhibitor

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

Cofactors

Small inorganic substances, such as $Zn$, $Fe$, or $Mg$ ions, that can 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 enzymes in capturing substrates.