1. Cellular Transport and the Cell Cycle
Unit 3
Chapter 8

2. Different ways of transporting materials across a cell membrane
Passive transport
Diffusion
Osmosis: water diffusion
Facilitated transport
Active transport
Exocytosis
Endocytosis

3. Cells in isotonic solutions
Cell loses and gains water at an equal rate.
Net change to cell = nothing

4. Isotonic solution
Not ideal for plant cells because the cells become flaccid (limp)
Ideal for animal cells or cells without cell walls

5. Cells in a hypotonic solution
More water moves into the cell than moves out.
Net change = cell mass increases

6. Hypotonic solution
Ideal for plant cell where the cell becomes turgid (swollen)
Not ideal for animal cells where the cell lyses (bursts)

7. Cells in a hypertonic solution
More water moves out of the cell than moves in
Net change = cell mass decreases

8. Hypertonic solution
Not ideal for any cell
Both shrink.

9. Passive transport
Movement of materials across a cell membrane in the direction of higher concentration to lower concentration
No ATP energy required

10. Passive transport by proteins
Facilitated transport
Movement of chemicals down a chemical gradient (from high to low concentration) through a protein

11. Passive transport

12. Channel vs. carrier proteins
Click on image to view video.

13. Active transport
Requires energy to move substances across the membrane against the concentration gradient (from lower to higher concentration)
Click on image to view video.

14. Exocytosis: transport of large particles out of cell

15. Endocytosis: transport of large particles inside of a cell

16. Cell reproduction: making new cells by a process called cell division
Cell cycle: sequence of growth and division of a cell
Step 1: Interphase (G1, S, G2)
Step 2: Mitosis and Cytokinesis (M)

17. Eukaryotic chromosome structure
Double helix coiled and twisted into a condensed structure
Bacterial DNA differs in that it is circular and not linear.

18. Step 1: Interphase Grows in size Copies DNA
Each chromosome makes a copy, and the two resulting chromosomes are joined at the centromere.

19. Step 2: Mitosis (nuclear division)
Prophase
Metaphase
Anaphase
Telophase

20. Prophase: spindle fibers extend, nuclear membrane disintegrates

21. Metaphase: chromosomes aligned along the middle

22. Anaphase: chromosomes pulled apart when spindle fibers become shorter

23. Telophase: two nucleus form at each pole of the cell

24. Cytokinesis: forming two daughter cells identical to the parent cell
Animal cells: cell pinches down the middle
Plant cells: cell plate forms to make new cell wall

25. Onion root tip showing phases of mitosis

26. Click on image to view video.
The cell cycle
Click on image to view video.