LAB QUIZ 1

Plasma membrane

The barrier around every cell, composed of a phospholipid bilayer with proteins, cholesterol, and carbohydrate chains.

Phospholipid bilayer

A double layer of phospholipid molecules where hydrophilic heads face outward and hydrophobic tails face inward.

Selectively permeable

A property of membranes that actively chooses which substances can cross based on size, charge, and transport proteins.

Active transport

Movement of substances against their concentration gradient requiring energy (ATP), e.g., sodium-potassium pump.

Passive transport

Movement of substances with the concentration gradient without energy, e.g., diffusion and osmosis.

Solvent

The substance that dissolves a solute, usually a liquid, e.g., water in biological systems.

Solute

The substance being dissolved, such as salts or sugars.

Concentration gradient

The difference in concentration of a substance between two areas.

Equilibrium

The state where particles are evenly distributed, resulting in no net movement.

Factors affecting diffusion

Temperature, concentration gradient size, molecule size, distance, and surface area all influence the rate of diffusion.

Diffusion

Movement of particles from high to low concentration.

Osmosis

The movement of water across a selectively permeable membrane from low solute concentration to high solute concentration.

Hypertonic solution

A solution with a higher concentration of solute outside the cell, causing cell shrinkage.

Isotonic solution

A solution with equal solute concentrations inside and outside the cell, allowing no net movement.

Hypotonic solution

A solution with a lower concentration of solute outside the cell, causing the cell to swell.

Crenation

The process where a red blood cell shrinks due to loss of water in a hypertonic solution.

Lysis

The bursting of a red blood cell when it takes in too much water in a hypotonic solution.