AP Biology 2.3-2.8

Plasma Membrane

Consists of a double layer of phospholipids and surrounds the cell, allowing some molecules to pass while blocking others.

Phospholipids

Molecules that make up the lipid bilayer of the plasma membrane, containing polar hydrophilic heads and nonpolar hydrophobic tails.

Amiphatic

Describes a molecule that has both a hydrophobic part and a hydrophilic part, such as phospholipids.

Fluid Mosaic Model

The concept that describes the plasma membrane as flexible, with proteins, lipids, and carbohydrates that move and function together.

Integral Proteins

Proteins embedded deep in the lipid bilayer of the plasma membrane, involved in transport and signaling.

Peripheral Proteins

Proteins that sit loosely on the surface of the plasma membrane, functioning as enzymes or signaling molecules.

Glycolipids

Lipids with carbohydrate chains that serve as identification tags and help with cell communication.

Glycoproteins

Proteins with sugar chains that play roles in signaling, cell adhesion, and protein protection/folding.

Selective Permeability

The property of the plasma membrane that allows some substances to cross while blocking others.

Aquaporins

Integral membrane proteins that facilitate rapid water movement across the plasma membrane.

Osmosis

The passive movement of water across a semi-permeable membrane from an area of lower solute concentration to higher concentration.

Diffusion

The passive movement of particles from an area of higher concentration to an area of lower concentration until evenly spread.

Concentration Gradient

The difference in concentration of a substance across a space which drives diffusion.

Passive Transport

The movement of substances across a cell membrane without the need for energy input, such as diffusion.

Active Transport

The movement of substances against their concentration gradient, requiring energy input.

Sodium-Potassium Pump

An active transport mechanism that moves sodium out and potassium into the cell, using ATP.

Membrane Potential

The electrical charge difference across the plasma membrane, resulting from the differential distribution of ions.

Exocytosis

The process in which a cell's internal vesicle fuses with the plasma membrane to release its contents outside.

Endocytosis

The process whereby a cell engulfs materials by folding its plasma membrane to form a vesicle.

Isotonic

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

Hypertonic

A solution with a higher concentration of solute outside the cell, causing water to move out and the cell to shrink.

Hypotonic

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

Cholesterol

A molecule that intersperses within the phospholipid bilayer, regulating fluidity and preventing extremes in membrane rigidity.

Nucleus

DNA Storage

Mitochondria

Energy production (ATP)

Smooth ER

Lipid production and detoxification

Rough ER

Protein production, exports out of cell

Golgi

Protein modification and transport

Lysosome

Digestive system of the cell

Ribosomes

Protein synthesis

Chloroplasts

Plants only; site of photosynthesis

Plant only structures

Cell wall, central vacuole, chloroplast

Ribosomes

Rough ER has _____ attached to it giving it a “rough” appearance

Lipids, detoxifies

Smooth ER makes ____ and ____ harmful substances