1. Miller & Urey’s Experiment
Purpose of Experiment: to observe the behavior of molecules under conditions that mimic Earth’s atmosphere before cells
Results of Experiment: confirmed that organic molecules could spontaneously form from inorganic molecules

2. Pasteur’s Experiment
Purpose of Experiment: to investigate whether sterile nutrient broth could spontaneously generate bacteria (life)
Results of Experiment: “cells can only come from pre-existing cells” (i.e. life can only come from life)

4. Overview of the Plasma Membrane:
Also called a “phospholipid bilayer”
Structure is described by the “Fluid Mosaic Model” or “Singer-Nicolson Model”
Membrane is “selectively permeable”; it regulates what enters and exits the cell
Selective permeability due to structure of membrane
Made up of phospholipids, cholesterol, and proteins.

5. Structure of Phospholipids & Their Arrangement in Membranes
Hydrophillic (polar) heads are made of glycerol and phosphate
Hydrophobic (non-polar) tails are made of fatty acid chains
Phospholipids are amphipathic b/c they contain both hydrophobic and hydrophilic parts
Phospholipids will spontaneously form into a bilayer

6. Properties of Phospholipid Bilayer
Structure of membrane is held together by weak interactions between the hydrophobic tails
Weak attraction allows phospholipids to move around, allowing for membrane fluidity and flexibility
Fluidity allows for spontaneous breaking and reforming of membranes

7. Bubbles & Cell Membranes

8. Fluid Mosaic Model (Singer-Nicolson Model) of Cell Membranes
“Fluid” – phospholipids can move around
“Mosaic” – phospholipid bilayer is embedded with proteins and cholesterol

9. Function of Cholesterol
Used for structural AND functional support of plasma membrane
Functions to immobilize outer surface of membrane & maintain physical integrity of membrane
Makes cell membrane less permeable to small water-soluble molecules
Excess or inadequate levels of cholesterol affect permeability of membrane

10. Types & Function of Proteins (JETRAT!)

11. What does it mean for a plasma membrane to be semi-permeable
What does it mean for a plasma membrane to be semi-permeable? Why is selective permeability important for cells/organisms?

12. What types of molecules and ions are membranes MOST permeable to?

13. How do molecules actually cross the membrane. (I. E
How do molecules actually cross the membrane? (I.E. How are molecules transported in and out of cells?)

14. Cellular Transport is Based on Concentration Gradients
Concentration Gradient: the presence of a difference in concentration of some material, going from one area to another
All forms of matter will move from areas of high concentration to lower concentration

15. Describing the Relative Concentration of Solutions
“hyper” = over “hypo” = below “iso” = same
A hypertonic solution is a solution with a HIGHER concentration of solutes OUTSIDE of the cell, compared to inside of the cell.
A hypotonic solution is a solution with a LOWER concentration of solutes OUTSIDE the cell.
An Isotonic solution is a solution with the same concentration of solutes as the inside of the cell.

16. 2 Categories of Transport Based on Use of Energy
ATP (Adenosine Triphosphate) is the form of energy used by most living organisms

17. Types of Passive Transport: Diffusion & Osmosis

18. Diffusion & Osmosis: Both involve the movement of substances
Diffusion & Osmosis: Both involve the movement of substances. Both involve movement across a concentration gradient.

19. What is osmosis?
Animation :

20. What direction would water move in relation to your cells
What direction would water move in relation to your cells? (AKA What direction would osmosis occur in?)

23. Facilitated diffusion is the passive net movement of particles, facilitated by channel proteins
Channel proteins are specific to the molecules they transport.

24. Active vs. Passive Transport Across Membranes