1. Discovering DNA

2. A bacteriophage is a virus that infects bacteria
The bacteriophage attaches to the bacteria and its genetic material then enters the bacterial cell. The bacterial cell treats the viral genetic material as if it was its own and subsequently manufactures more virus particles
DNA inside protein coat
Hollow sheath
Question: what infects the bacterium, the protein or the DNA?
Tail fiber

3. Hershey and Chase show protein does not infect the bacterium (1952)
virus particle labeled with 35S
DNA being injected into bacterium
Hershey and Chase show protein does not infect the bacterium (1952)
35S remains outside cells

4. Hershey and Chase show DNA infects the bacterium
virus particle labeled with 32P
DNA being injected into bacterium
Hershey and Chase show DNA infects the bacterium
32P remains inside cells

5. Types of Cell Reproduction
Asexual reproduction involves a single cell dividing to make 2 new, identical daughter cells
Mitosis & binary fission are examples of asexual reproduction
Sexual reproduction involves two cells (egg & sperm) joining to make a new cell (zygote) that is NOT identical to the original cells
Meiosis is an example

6. Types of Cell Reproduction
Asexual
Sexual

7. Cyclins Oncogenes and Cancer

8. Life Cycle of a Cell
Mitosis is the division of somatic/autosomal (body) cells

9. Interphase Interesting things happen! Cell preparing to divide
Genetic material doubles

10. The Cell Cycle DNA Copied Cells prepare for Division Cells Mature
Daughter Cells
Cell Divides into Identical cells

11. Chromosomes in Dividing Cells
Duplicated chromosomes are called sister chromatids & are held together by the centromere
Sister Chromatids

12. Mitosis Prophase (Sister Chromatids pair up )
Metaphase (meet in the middle)
Anaphase (apart)
Telophase (two)

13. Prophase Chromosome pair up! Chromosomes thicken and shorten
-become visible
-Sister chromatids are joined by a centromere and are ready to begin cell division
Centrioles move to the opposite sides of the nucleus
Nucleolus disappears
Nuclear membrane disintegrate

14. Prophase

15. Metaphase Chromosomes meet in the middle!
Chromosomes arrange at equator of cell
Become attached to spindle fibers by centromeres
Homologous chromosomes do not associate

16. Metaphase

17. Anaphase Sister chromatids get pulled apart
Spindle fibers contract pulling chromosomes to the opposite poles of the cell

18. Anaphase

19. Telophase Now there are two! Chromosomes uncoil Spindles disintegrate
Nucleolus reappears
Nuclear membrane reappears
CYTOKINESIS occurs
Chromosomes reappear as chromatin

20. Telophase