AP Bio 2.1-2.2

Plasma Membrane

A selectively permeable phospholipid bilayer that surrounds the cell and regulates transport.

Nucleus and Nuclear Envelope

The DNA-containing control center enclosed by a double membrane with pores continuous with the ER.

Ribosomes

Nonmembranous rRNA-protein complexes that translate mRNA sequences into polypeptides.

Free vs. Bound Ribosomes

Free make cytosolic proteins

Endomembrane System

A network of membranes that modifies

Transport Vesicles

Small membrane sacs that move materials between organelles in the endomembrane system.

Golgi Apparatus

A stack of flattened sacs that modifies

Mitochondria

Double-membraned organelles that carry out aerobic respiration and produce most cellular ATP.

Lysosomes

Membrane-bound sacs of hydrolytic enzymes that digest materials and recycle cell components.

Chloroplasts

Double-membraned organelles in plants and algae where photosynthesis converts light energy to chemical energy.

Prokaryotic vs. Eukaryotic Cells

Prokaryotes lack membrane-bound organelles and a nucleus

Plant vs. Animal Cells

Plant cells have cell walls and chloroplasts

Endoplasmic Reticulum (Rough and Smooth)

A membrane network that supports cell shape

Vacuoles

Membrane-bound sacs that store materials

Surface Area-to-Volume Ratio

The amount of membrane surface available for exchange relative to internal cell volume.

Surface Area and Volume Formulas

Sphere: SA 4πr²

Calculating SA:V Ratio

Find surface area and volume with the correct formula

Exchange of Materials and SA:V

Higher ratios allow faster nutrient uptake

Membrane Folding and SA:V

Folds increase surface area greatly without much increase in volume.

Root Hairs

Thin extensions of root epidermal cells that increase surface area for water and mineral absorption.

Guard Cells and Stomata

Paired cells regulate stomatal openings

Gut Epithelial Cells and Microvilli

Intestinal lining cells have membrane projections that increase surface area for nutrient absorption.

Cilia

Short hairlike cell projections that increase exposed surface and help move materials past cells.

Heat Exchange and Body Size

Smaller bodies lose heat faster because they have more surface area relative to volume.

Metabolic Rate per Unit Body Mass

Smaller multicellular organisms usually use energy faster per gram than larger organisms.

Cell Size Limits and Plasma Membrane Exchange

As cells grow