Cell Membrane and Transport Bio Exam

Lipid bilayer

A double layer of phospholipids that forms the foundation of all cell membranes, providing a flexible barrier between the inside and outside of the cell.

Integral proteins

Proteins embedded within the lipid bilayer that span the membrane or are permanently attached; involved in transport, signal transduction, or acting as receptors.

Peripheral proteins

Proteins located on the inner or outer surface of the cell membrane; they help with signaling, cell recognition, and anchoring the cytoskeleton.

Glycolipids

Lipids with carbohydrate chains attached that help with cell recognition and provide energy for the cell.

Glycoproteins

Proteins with carbohydrate chains attached that play key roles in cell-cell recognition and immune response.

Cholesterol

A lipid molecule embedded within the phospholipid bilayer that helps regulate membrane fluidity, stability, and flexibility.

Passive Transport

The movement of molecules across the cell membrane without the use of energy, moving down their concentration gradient.

Simple Diffusion

The process where small, nonpolar molecules (like oxygen or carbon dioxide) move directly across the lipid bilayer from high to low concentration.

Facilitated Diffusion

The movement of larger or polar molecules through transport proteins (such as channels or carriers) from high to low concentration without using energy.

Osmosis

The diffusion of water across a selectively permeable membrane, moving from areas of low solute concentration to high solute concentration.

Isotonic solution

A solution in which the concentration of solutes is equal inside and outside the cell, resulting in no net movement of water.

Hypertonic solution

A solution that has a higher solute concentration than the inside of the cell, causing water to leave the cell and the cell to shrink (crenate).

Hypotonic solution

A solution that has a lower solute concentration than the inside of the cell, causing water to enter the cell and the cell to swell or burst (lyse).

Active Transport

The movement of molecules across the membrane using energy (ATP) to move substances against their concentration gradient.

Sodium-Potassium Pump (Na+/K+)

An example of active transport that moves three sodium ions out of the cell and two potassium ions into the cell using ATP to maintain proper charge balance and cell potential.

Bulk Transport

The movement of large particles or fluids into or out of the cell using vesicles; requires energy.

Exocytosis

A type of bulk transport where vesicles fuse with the plasma membrane to release substances out of the cell, such as hormones or waste.

Endocytosis

A type of bulk transport where the cell takes in materials by engulfing them in a vesicle formed from the plasma membrane.

Phagocytosis

A form of endocytosis known as "cellular eating" where the cell engulfs large particles like bacteria or debris.

Pinocytosis

A form of endocytosis known as "cellular drinking" where the cell takes in fluids and dissolved solutes.

Receptor-mediated endocytosis

A specific type of endocytosis where molecules bind to receptors on the cell surface before being engulfed, allowing selective uptake of substances.