AP Biology Unit 2 Reference: Cell Structure & Function

Endosymbiotic Theory

Explains how eukaryotes evolved from prokaryotes, involving engulfing non-photosynthetic and photosynthetic prokaryotes.

Compartmentalization

The defining characteristic of eukaryotic cells, allowing for separate local environments within the cell.

Nucleus

Houses the cell's genetic material (DNA) and is surrounded by a nuclear envelope with pores.

Ribosomes

Non-membrane bound structures responsible for protein synthesis and composed of rRNA and proteins.

Endoplasmic Reticulum (ER)

An organelle that regulates protein traffic, with Rough ER involved in protein synthesis and Smooth ER in lipid synthesis and detoxification.

Golgi Complex

Flattened membrane sacs that modify, package, and transport proteins, key for glycosylation.

Lysosomes

Membrane sacs containing hydrolytic enzymes used for intracellular digestion.

Vacuoles

Storage organelles in cells, with plant central vacuoles maintaining turgor pressure.

Mitochondria

Organelle responsible for cellular respiration, ATP production, having a highly folded inner membrane for efficiency.

Chloroplasts

Organelles involved in photosynthesis, converting solar energy to chemical energy.

Surface Area to Volume Ratio (SA:V)

Critical measurement for cells affecting nutrient exchange rates; cells must maintain a high ratio to survive.

Fluid Mosaic Model

Describes the structure of cell membranes as a flexible layer of lipids with various proteins embedded.

Passive Transport

Movement of molecules across membranes down the concentration gradient without ATP, including diffusion and osmosis.

Active Transport

Movement of molecules against the concentration gradient using ATP, involves mechanisms like protein pumps.

Osmoregulation

The process by which cells regulate water potential and solute concentrations to maintain homeostasis.

Water Potential ()

Total potential for water movement, calculated as  = p + s.

Hydrophilic

Water-attracting; describes the head of phospholipids in cell membranes.

Hydrophobic

Water-repelling; describes the tails of phospholipids in cell membranes.

Tonicity

The relative concentration of solutes in solutions that determines the movement of water.

Glycosylation

The process of adding carbohydrate tags to proteins to create glycoproteins and glycolipids.

Cristae

The folds of the inner mitochondrial membrane that increase surface area for ATP production.

Thylakoids

Membrane discs in chloroplasts containing chlorophyll; sites of light-dependent reactions.