1. Chapter 4: Cell structure

2. Eukaryotic cell: Main components: Cell wall/ or membrane
Cytoplasm (cytosol)
Nucleus
Name the functions of each?

3. Cell walls Plants, bacteria and fungi have cell walls
Plants: cell walls made of cellulose
bacterial cell walls made of peptidoglycan
Fungi: cell walls made of chitin

4. Cell membranes Made of: lipids, proteins Primary lipids: phospholipids
Make excellent barriers; inside of cell is aqueous (watery) and they form an “oily” layer between inside and outside in the cell
Cell membrane: selectively permeable (allows only certain things to pass and restricts others)

5. Phospholipid: Have polar and non-polar regions Form lipid bilayers
Phosphate is polar (hydrophilic)
Fatty acid is non polar (hydrophobic)
Form lipid bilayers

6. 4 ways substances cross cell membrane
1. Simple diffusion
2. Facilitated diffusion
3. Active transport
4. Bulk transport

7. 1. Simple diffusion
Diffusion: movement of substance from area of high concentration to area of low concentration until dynamic equilibrium is reached “moving down concentration gradient” concentration gradient: when there is a change in the concentration of something over a distance equilibrium: equal on both sides (balanced) Only works if substance is lipid soluble (hydrophobic) and can interact with the oily layer ex: oxygen, carbon dioxide, cholesterol

8. 2. Facilitated diffusion
Similar to simple diffusion except molecules that cross are not hydrophobic
They cannot interact with bilayer and cannot simply cross the membrane
Require the help of proteins to facilitate the movement of these substances

9. 3. Active transport
Cell must use energy to move something across the membrane
Active transport: (differs from simple and facilitated diffusion in that it can move things against a concentration gradient) requires energy
Relies on membrane proteins

10. 4. Bulk transport
Movement of large, bulky items across the cell membrane
Endocytosis (take into the cell)
Exocytosis (release from the cell)

11. Endo/exocytosis Endocytosis:
Cell takes up some particle from surroundings by engulfing it within a pocket called a vesicle
Phagocytosis: eating
Pinocytosis: drinking
Exocytosis: the exact opposite of endocytosis
Release of particle to outside through vesicle

12. Osmosis:
Movement of water across cell membrane down its concentration gradient
Water’s concentration gradient is opposite to the solute (dissolved particles) concentration gradient
Water is hydrophilic must cross membrane by facilitated diffusion
Hypertonic (cell in concentrated solution)
Cell shrivels
Isotonic (same concentration)
Hypotonic (cell in dilute solution)
Cell swells (lyses)

13. The cytoplasm:
Cytoplasm: semiliquid goo that contains eukaryotic cell’s organelles Prokaryotic cells: have no organelles (bacteria)
Know: organelles and functions!

14. Chemical reactions and enzymes (in cytoplasm): Enzymes
Enzymes are proteins; large biological molecules that are responsible for thousands of metabolic processes (catalysts that serve to accelerate rate/ specificity of metabolic reactions)
Specific 3D shapes give them specificity for particular reactions
Denaturation of proteins results in loss of function

15. Catalysts: Speed up a chemical reaction
Are not used up in the chemical reaction (re-usable)
Enzymes are specific for particular reactions