The cell is the basic functional unit of life. They can live on their own in cell culture.  The Cell Theory states: 1. All living things are made of cells 2. The cell is the basic unit of structure and function 3. New cells can only arise from existing cells  Organelles are structures within the cell that perform specific functions for survival.  Know functions of cell organelles Nucleus – contains DNA, Nucleolus – produces ribosomes,  Ribosomes – protein synthesis (manufactures protein), Vacuoles – Storage, Endoplasmic reticulum – transport of proteins, Lysosomes – digestion of food/bacteria, Golgi apparatus – protein modification and transport, Centrioles – cell division, Mitochondria – energy/ATP.  Know non-organelle structures of a cell: Cell membrane – entry/exit to or from cell (found in ALL cells), Cell wall – Rigid (all kingdoms except Animal), Cytoplasm – colloid liquid in the cell.  Chloroplasts capture light energy for photosynthesis.  Cell membranes are made of phospholipids and proteins. They are selectively permeable, meaning some things can pass through and other can’t. The size of something is the biggest factor regarding passage.  Cholesterol is important in cell membranes because 1. It helps to keep the membrane together 2. It makes the membrane more flexible 3. It makes it more difficult to allow passage of hydrophilic substances.  The current model of the cell membrane is the Fluid Mosaic Model. Fluid means able to move, while mosaic suggests a pattern created by small materials.  Cell membranes have embedded proteins like channel or gated proteins that help substances pass through.  Cell walls in plants are plants are made of cellulose and provide structural support.  Cytoplasm is the medium through which substances travel in a cell.  Passive transport is high to low. No energy needed. It’s like going downhill. ex. diffusion, osmosis, facilitated diffusion (involves help from membrane proteins)  Active transport is low to high. Energy required. It’s like going uphill.  Tonic solutions are 1. Hypertonic – has more solute than the cell. Draws water out of a cell and shrinking occurs. Ex. Strong salt water. 2. Isotonic – has the same solute level as the cell. The cell stays the same. Ex. Tap water. 3. Hypotonic – has less solute than the cell. Causes water to move into the cell and it swells or bursts.  Ex. Distilled water.

The phospholipid to the left has a phosphate head and 2 fatty acid tails. The head is hydrophilic (love water), but the tails are hydrophobic (fear water). The small arrow points to a bent fatty acid tail. Why is it bent? It is bent because it is made of an unsaturated fatty acid which has a double bond between carbon atoms. The straight tail is made of a saturated fatty acid.