AP Bio - Unit 2: Cell Structure and Function

What are the fundamental units of life?

Cells.

What are the two main types of cells?

Prokaryotic and eukaryotic.

Do prokaryotic cells have a nucleus?

No; they lack a membrane bound nucleus.

Do eukaryotic cells have organelles?

Yes; they contain membrane bound organelles.

Example of a prokaryote?

Bacteria.

Example of a eukaryote?

Plants and animals.

Why are cells small?

Small cells have a higher surface area to volume ratio for efficient exchange.

What happens when a cell grows too large?

Material exchange becomes less efficient.

How do eukaryotic cells deal with large size?

By compartmentalization and specialized shapes.

What does the Endosymbiotic Theory explain?

How mitochondria and chloroplasts evolved from prokaryotes.

What evidence supports it?

Circular DNA, prokaryote like ribosomes, and double membranes.

Mitochondria resemble what?

Ancient aerobic bacteria.

Chloroplasts resemble what?

Cyanobacteria.

What is the plasma membrane made of?

A phospholipid bilayer.

What is the fluid mosaic model?

A dynamic membrane of moving phospholipids and proteins.

Which parts of phospholipids are polar and nonpolar?

Heads = hydrophilic; tails = hydrophobic.

What do embedded proteins do?

Transport, signaling, support, and enzymatic activity.

What does cholesterol do in membranes?

Regulates fluidity.

What do glycoproteins and glycolipids do?

Help in cell recognition and communication.

What molecules pass freely through the membrane?

Small, nonpolar molecules (O₂, CO₂).

What molecules need transport proteins?

Large polar molecules and ions.

What helps water move faster across membranes?

Aquaporins.

Does passive transport need energy?

No, it moves down the concentration gradient.

What is simple diffusion?

Molecules moving directly through the bilayer.

What is facilitated diffusion?

Molecules moving through channel or carrier proteins.

What is osmosis?

Diffusion of water across a membrane.

What is osmosis driven by?

Water potential differences.

What happens in a hypotonic solution?

Water enters; animal cells may burst, plant cells become turgid.

What happens in a hypertonic solution?

Water exits; animal cells shrink, plant cells plasmolyze.

What happens in an isotonic solution?

No net water movement; animal cells stay normal.

Does active transport require energy?

Yes, usually ATP.

What does the sodium potassium pump do?

Pumps Na⁺ out and K⁺ in, maintaining gradients.

What is secondary active transport?

Uses one molecule’s gradient to move another against its gradient.

What is endocytosis?

Cell takes in materials by forming vesicles.

What is phagocytosis?

Cell “eating” large particles.

What is pinocytosis?

Cell “drinking” extracellular fluid.

What is receptor mediated endocytosis?

Selective uptake of specific molecules via receptors.

What is exocytosis?

Vesicles release materials outside the cell.

What does compartmentalization do in eukaryotes?

Increases metabolic efficiency.

What does the mitochondrion do?

Produces ATP through cellular respiration.

What do chloroplasts do?

Perform photosynthesis in plants and algae.

What does the rough ER do?

Synthesizes and folds proteins.

What does the smooth ER do?

Synthesizes lipids and detoxifies.

What does the Golgi apparatus do?

Modifies, packages, and ships proteins and lipids.

What do lysosomes do?

Break down macromolecules and old organelles.

What do vacuoles do?

Store materials and maintain plant turgor pressure.

What do ribosomes do?

Build proteins from mRNA instructions.

How are the ER, Golgi, and vesicles connected?

Proteins made in the ER → modified in the Golgi → exported via vesicles.