Chapter 5 - The Working Cell

Q: What is diffusion?
A: Diffusion is the passive movement of a solution across a membrane in order to evenly spread out in the available space.
Q: What is a hypotonic solution?
A: A hypotonic solution is a solution with a solute concentration lower than that of the cell.
Q: What is facilitated diffusion?
A: Facilitated diffusion is when a protein makes it possible for a substance to move down its concentration gradient.

Five Main Facts:
1) A cell will shrink in a hypertonic solution and swell in a hypotonic solution. This is the tonicity of a cell.
2) Energy is the capacity to perform work. Cells use energy as well as store it in many different ways for many different uses.
3) Chemical reactions are present in all cells. They require energy and yield products rich in potential energy.
4) Enzymes are protein catalysts that decrease the energy of activation.
5) Membranes are a fluid mosaic, with protein molecules embedded in a phospholipid bilayer.

This is a diagram of a phospholipid bilayer. It consists of proteins and other molecules that allow certain compounds to flow in and out of the cell.

Chapter five described how cells allow for atoms to flow in and our freely. The use of diffusion, passive transport and active transport allow for this to happen. A cell must have energy in order to perform many of these functions. Chemical reactions are also a necessity for the function of a cell. 

Key Terms:

1) Osmosis: diffusion of water molecules across a selectively permeable membrane

2) Tonicity: the ability of a solution fo cause a cell to gain or lose water

3) Isotonic: a cell in an equal volume of solute

4) Hypotonic: solution with a solute concentration lower than that of the cell

5) Hypertonic: solution with a higher solute concentration

6) Facilitated diffusion: when proteins make it possible for a substance to move down its concentration gradient

7) Pinocytosis: cellular drinking

8) Entropy: a measure of disorder

9) Kinetic energy: energy of motion

10) Heat: thermal energy, a form of kinetic energy associated with the random movement of atoms of molecules

http://www.youtube.com/watch?v=sdiJtDRJQEc