Plasma Membrane

Plasma Membrane

Fluid Mosaic Model

is a model that describes the structure of cell membranes with a flexible combination of lipid bilayers and proteins, where proteins can move within the lipid layer, creating a mosaic-like appearance. Not Expandable

Intergral Proteins

embedded in membrane (partially or all the way)

Peripheral Protiens

Sit on one side of the bilayer (Attached)

Lipid Bilayer Permeable to…

Hydrophobic molecules, Small uncharged polar molecules

Lipid Bilayer Impermeable to..

Ions, Large molecules

Diffusion

Movement of particles from high to low concentration. Moves down a concentration gradient

Dynamic Equilibrium

Diffusion ends in dynamic equilibrium

Passive Transport

• No energy input required,

• Relies on solute or solvent particles following their gradient until equilibrium is reached

Active Transport

• Energy input required (ATP)

• Goes against gradient

O2 Simple Diffusion

where molecules move from an area of high concentration to an area of low concentration without the cell using energy (ATP).

Osmosis

where water moves across a selectively permeable cell membrane from an area with low solute concentration to an area with high solute concentration.

Hypertonic

• Water movement INTO cell

• HIGH salt concentration

• Swells

Hypotonic

• Water movement OUT cell

• LOW salt concentration

• Shrinks

Isotonic

• EQUAL movement of water

• EQUAL concentration

• Stays same

Facilitated Transport: Passive Protein Transport

molecules move across the cell membrane using transport proteins WITHOUT requiring energy (ATP).

Channel Protein

• Form openings or tunnels in the membrane.

• Allow specific substances to pass through.

• Example: ions moving through ion channels.

Carrier Protien

• Bind to a specific molecule.

• Change shape to move the molecule across.

• Example: glucose entering cells.

Aquaporin

special channel proteins in the cell membrane that allow water to move across the membrane quickly

Glucose Transporter

type of carrier protein in the cell membrane that helps glucose (sugar) move into or out of a cell.

Primary active transport – Na+-K+ Pump

active transport that uses energy (ATP) to move sodium and potassium ions across the cell membrane AGAINST their concentration gradients.

• 3 sodium ions (Na⁺) OUT of the cell.

• 2 potassium ions (K⁺) INTO the cell.

• Uses 1 ATP for energy during each pump cycle.

Electrochemical gradient

How positive and negative charges attract or repel each other.

• Positive and negative charges ATTRACT.

• Positive and positive charges REPEL.

• Negative and negative charges REPEL.

• The inside of a cell is usually more negative than the outside.

• Sodium (Na⁺) is positively charged.

• The positive sodium is attracted to the negatively charged inside of the cell.

Secondary Active Transport

type of active transport that uses energy stored in an electrochemical gradient to move substances across a cell membrane.

Bulk Transport

how cells move large substances or large amounts of materials into or out of the cell using small membrane-bound sacs called vesicles. requires energy (ATP).

Endocytosis

moving materials INTO the cell by forming new vesicles from the plasma membrane

Exocytosis

• A vesicle containing materials moves toward the cell membrane.

• The vesicle joins (fuses) with the cell membrane.

• The vesicle releases its contents outside the cell.

Phagocytosis

type of endocytosis where a cell takes in large particles, such as bacteria or other foreign materials

Pinocytosis

type of endocytosis where a cell takes in liquids and dissolved substances from outside the cell.