AP Test Cell Review

Basic Definitions A cell is the basic unit of life. All living things are made of cells. Inside cells are organelles, which are small, membrane bound structures that have specific jobs. Cells are small because nutrients and water must be able to get to all parts of the cell (higher surface area to volume ratio with smaller cells)

Eukaryotic vs. Prokaryotic A prokaryotic cell does NOT have a nucleus or membrane bound organelles. It is small and simple, having only cytoplasm (fluid) and ribosomes (organelles that make protein). Bacteria are prokaryotic. A eukaryotic cell DOES have a nucleus and organelles. They are larger and more complex, and include plants and animals.

Animal vs Plant Cell

Review of the Endomembrane System

AP Biology Phospholipids Fatty acid Phosphate  Phosphate head  Hydrophilic and polar  Fatty acid tails  Hydrophobic and non polar  Arranged as a bilayer Aaaah, one of those structure–function examples “repelled by water” “attracted to water”

AP Biology Permeability to polar molecules?  Membrane becomes semi-permeable via protein channels  specific channels allow polar substances like water, ions, and sugars across cell membrane inside cell outside cell sugaraa H2OH2O salt NH 3

AP Biology Getting through cell membrane  Passive Transport  Simple diffusion  diffusion of nonpolar, hydrophobic molecules  lipids  HIGH  LOW concentration gradient  Facilitated transport  diffusion of polar, hydrophilic molecules  through a protein channel  HIGH  LOW concentration gradient  Active transport  diffusion against concentration gradient  LOW  HIGH  uses a protein pump  requires ATP ATP

AP Biology Osmosis is just diffusion of water  Water is very important to life, so we talk about water separately  Diffusion of water from HIGH concentration of water to LOW concentration of water  across a semi-permeable membrane

AP Biology Concentration of water  Direction of osmosis is determined by comparing total solute concentrations  Hypertonic - more solute, less water  Hypotonic - less solute, more water  Isotonic - equal solute, equal water hypotonichypertonic water net movement of water