1. Cell Structure and physiology
BSC 2010 L

2. Cells Cells are the basic unit of life Cell Theory
All living things are composed of cells and
Cells come only from other cells

3. Cells In this lab, we will look at a couple different things:
Cell Structure
Difference between prokaryotes and eukaryotes
Eukaryotes – difference between plant and animal cells
Function of organelles
Plasma membranes
Contents of the cell are bounded by plasma membrane
Regulates movement of molecules into and out of the cytoplasm
We will look at the how the passage of water into a cell depends on the difference in concentration of solutes between cytoplasm and the surrounding medium pH
Well-being of cells also depends upon pH surrounding them
We will look at how a buffer can maintain pH within a narrow range and how buffers within cells can protect them from damaging pH changes

4. Prokaryotic cell
Eukaryotic Cell
Bacteria
Protists, fungi, plants, animals

5. Eukaryotic Cells
Know the name and function of organelles found in eukaryotic cells
Know differences between plant cells and animal cells!

6. Living Plant Cells
Looking at the Elodea Leaf

7. Animal Cells
Human Cheek Cells

8. pH pH of a solution tells its hydrogen ion concentration - H+
Buffer – system of chemicals that takes up excess H ions or hydroxide ions
Maintaining pH is VERY important in biological systems
i.e. – human blood pH must be maintained at 7.4
Exercise 4.5
You will test the buffering capacity of 3 solutions
Water, inorganic solution, simulated cytoplasm
Which one do you think will be able to hold its pH the longest as drops of HCl are added?

9. pH Results Contents pH before acid pH after acid Additional acid
Distilled Water
~ 6.5
3.0
2.0
Inorganic Buffer
7.0
5.5
Cytoplasm
6.5

10. Diffusion
Movement of molecules from a higher to a lower concentration until equilibrium is achieved
Dependent on temperature, size of molecules, and type of medium (solid, semi-solid, liquid, air)

11. Types of Diffusion Air Liquid Semi-solid Semi-permeable membrane
Dialysis tubing

12. Diffusion
Diffusion of methylene blue in agar (semi-solid) versus water (liquid)
In which medium did the dye diffuse the fastest?

13. Osmosis – Diffusion of Water across semi-permeable membrane
We will see what happens with animal cells -red blood cells
And plant cells – potato and elodea

14. Tonicity
Relative concentration of solute (particles) or solvent (water) outside the cell compared to inside
3 Types
Isotonic
Hypertonic
Hypotonic

15. Tonicity and red blood cells
Check out tubes of prepared red blood cell solutions

17. Tonicity and Elodea Cells
Isotonic
Hypertonic
In 10% NaCl solution
Water has left the cell across the plasma membrane
Notice how cell membrane has shrunk away from cell wall and chloroplasts are all clustered in middle

18. Osmosis Experiment