1. Review last week

2. DNA Structure Nucleotides have: A sugar molecule A phosphate molecule
A nitrogenous base molecule

3. DNA Structure
Each nucleotide has one of four different nitrogenous bases
Adenine (A), Thymine (T), Cytosine (C), Guanine (G)
Which bases pair together?
A with T (vice versa)
C with G (vice versa)

4. The Genetic Code
DNA has a _______-character code, which form _______________(i.e. GGC)
Each 3 letter word codes for the production of one of 20 different amino acids

5. Definition
These are a short section of DNA that contains instructions to make a specific protein
GENES

6. The Cell Cycle

7. The Cell Cycle
At any moment, there are millions of cells going through cell division
But what about the trillions of cells that aren’t? What are they doing?
They are in some phase of the Cell Cycle

8. The Cell Cycle

9. The Cell Cycle
The cell cycle is a sequence of events in the cell from one cell division to another.
The growing and working phase of the cell is called interphase

11. The Cell Cycle
A cell is in interphase for 90% of the total time of the cell cycle.
During interphase a cell will:
Make copies of each organelle
Make copies of chromosomes (DNA)
Each chromosome and its copies = sister chromatids

12. Cell Division

13. Cell Division What needs to happen in order for cells to divide?
DNA needs to copy itself (chromosomes)
Chromosomes
Thread-like structures containing DNA

14. Cell division
There are two types of cell division:
Mitosis
Meiosis

15. Mitosis
One cell splits into two identical daughter cells

16. What is mitosis for?
Mitosis is used to produce new body cells (eg. for growth and repair).
Simple plants and animals can also use mitosis to reproduce
This is called Asexual reproduction

17. What happens before mitosis?
1. The chromosomes get thicker

18. What happens before mitosis?
2. The chromosomes are replicated and can now be seen as x-shapes

19. What happens in mitosis?
3. The nuclear membrane disappears. The chromosomes line up on the spindle. The chromosomes are pulled to opposite ends of the cell

20. What happens in mitosis?
4. Each new cell is IDENTICAL to the original and has THE SAME number of chromosomes

21. Mitosis The stages of mitosis are: Prophase Metaphase Anaphase
Telophase
*Each stage has specific details about what is happening to the cell during mitosis

22. Cytokinesis Cytokinesis is the second process of cell division
It divides the cytoplasm into two daughter cells

23. Question 1
If a cell with 28 chromosomes divides into 2 new cells, how many chromosomes will each new cell have?
28 chromosomes

24. Question 2
True or False . . .
The cells produced in mitosis are genetically identical
TRUE