UNIT 2 AP BIO

Ribosomes

Cellular structures made of rRNA and proteins that produce proteins based on mRNA sequences, found in all cells.

Endomembrane System

A system that modifies, packages, and transports cellular products in vesicles.

Smooth ER

Involved in detoxifying cells and synthesizing lipids.

Rough ER

Embedded with ribosomes, it separates cell parts and assists in protein synthesis.

Golgi Complex

A flattened membrane sac that modifies and packages proteins for shipping; known as the shipping center of the cell.

Mitochondria

Organelles that synthesize ATP, known as the powerhouse of the cell.

Lysosomes

Organelles that break down waste and aid in apoptosis (programmed cell death).

Vacuoles

Sacs that store materials; large vacuoles in plant cells maintain turgor pressure and store nutrients and water.

Chloroplast

Organelles found in plants and algae, involved in photosynthesis, containing thylakoids.

Surface Area to Volume Ratio

The relationship that indicates higher efficiency in material exchange when surface area is greater relative to volume.

Plasma Membrane

The membrane that controls what comes in and out of the cell, embedded with proteins, steroids, and glycoproteins.

Fluid Mosaic Model

The model describing the plasma membrane structure where proteins and lipids can move around fluidly.

Selectively Permeable Membrane

A membrane that allows certain molecules to pass while blocking others, due to the arrangement of phospholipids.

Diffusion

The tendency of particles to move from an area of high concentration to low concentration.

Passive Transport

Movement of molecules from high concentration to low concentration without using energy.

Active Transport

Movement of particles across a membrane against the concentration gradient, requiring energy.

Endocytosis

Active transport that involves the membrane folding in to take in large molecules and particles.

Exocytosis

Active transport where vesicles release materials from the cell by fusing with the plasma membrane.

Facilitated Diffusion

Passive transport that requires channel proteins for the movement of specific molecules.

Osmosis

The diffusion of water across a selectively permeable membrane from high water potential to low water potential.

Hypotonic Environment

An environment where cells gain water; beneficial in plant cells as it leads to turgidity.

Hypertonic Environment

An environment where cells lose water, leading to cell shrinkage.

Isotonic Environment

An environment where cells have no net gain or loss of water.

Membrane Potential

A difference in charge across a membrane, essential for nerve and muscle cell function.

Sodium-Potassium Pump

An active transport mechanism that pumps 3 Na+ out and 2 K+ into the cell, maintaining resting membrane potential.

Compartmentalization in Cells

The separation of cellular processes in eukaryotic cells through internal membranes, making processes more efficient.

Endosymbiosis Theory

The theory that certain organelles, like mitochondria and chloroplasts, evolved from prokaryotes that were engulfed by larger cells.