1. Updates:
Unit 5 Test today!
Homework:
PreAP reproduction responses due tomorrow
Read 5.1, 8.3
Keystone Biology Exam: 5/20, 5/21

2. LEQ: Why do cells divide?
Activator:
Sexual reproduction/asexual reproduction
Weirdest, most interesting?
Key terms: cell cycle

3. reproduction can result in exponential growth
All cells reproduce through a division of a parent cell
Exponential growth of a population is possible, but rare
Limiting factors
Examples?

4. Asexual reproduction requires no additional individuals
Favorable environment
Nutrients
Result is a genetic clone

5. Cell Division in Eukaryotes Overview:
Division in eukaryotes is managed to coordinate the copying of a large cell with a large amount of DNA
Copy the original cell’s DNA (clone); asexual
Altering patterns of gene expression allows cells in bodies to specialize

6. Howard and Pelc demonstrated cell division in bodies
The cell cycle is a regular pattern of growth and division displayed by many cells.
Gap 1 (G1)
DNA synthesis (S)
Gap 2 (G2)
Mitosis (M)

8. Many cells in a multicellular organism carry out their lives in G0:
normal biological functions as they enter G1
Non-dividing (arrest)
Neurons, skeletal muscle

10. Discussion:
Do you think the scientific community should be permitted to conduct research on stem cells?
Why or why not?
What are the pros/cons, if any?

11. Summary:
Which stages of the cell cycle generally require about the same amount of time in all human cells?
During which stage of the cell cycle is the DNA copied?
What limits the maximum size of a cell?
Speculate: what are the consequences for a tissue/body if cell division proceeds in an unregulated manner? List several thoughts.

12. Answers:
Synthesis (s)
S, G2, and M stages
The ratio of cell surface area to volume
The cells would probably look large and have two nuclei located at opposite sides of the cell.