1. Cell Cycle

2. Chromosomes Compact, coiled DNA Chromatid Centromere
One half of the chromosome
Centromere
Between the two chromatids
holds them together

3. Number of Chromosomes Humans have 46 chromosomes
2 are sex chromosomes are autosomes

4. Types of chromosomes Sex chromosomes Autosomes
Chromosomes that determine the sex of an organism
Humans have an X or Y chromosome
Male: XY
Female: XX
Autosomes
All other chromosomes in an organism

5. Homologous Chromosomes
There are only 23 different chromosomes
To have 46 we have two copies of each chromosome
We get one from our mom and one from our dad
The pairs of each chromosome are called homologues
Homologues are the same size, shape, and carry the same genes

6. Karyotype Show’s the 23 pairs of chromosomes
22 homologous pairs of autosomes
1 pair of sex chromosomes

7. Diploid & Haploid Diploid (2n) Haploid (n)
Cells that have 2 sets of chromosomes
All cells, other than reproductive cells, are diploid
Haploid (n)
Cells that have only 1 set of chromosomes
Reproductive cells (sperm & eggs) are haploid

8. Cell Division All cells come from preexisting cells Prokaryotes
Binary Fission
Eukaryotes
Mitosis
Meiosis

9. Binary Fission The chromosome makes a copy of itself
The cell grows until it reaches about 2x it’s size
A cell wall forms between the two chromosomes and the cell splits

10. Mitosis How all cells divide EXCEPT reproductive cells
The cytoplasm and nucleus both divide
Results in two cells that are genetically identical

11. Mitosis – Cell Cycle Interphase Cell Division
Time between cell divisions
Cell Division
Time when the cell is dividing

12. INTERPHASE G1 phase S phase G2 phase Grow to mature size DNA is copied
Prepares for cell division

13. Mitosis - Prophase DNA is shortened and tightened into chromosomes
Nucleolus & nuclear membrane break down & disappear
Two centrosomes appear
Animals also have centrioles
Centrosomes move to opposite poles of cell
Spindle fibers radiate from centrosomes

14. Mitosis - Metaphase
Spindle fibers move chromosomes to the center of cell

15. Mitosis - Anaphase
Chromatids separate at the centromere and are pulled to opposite poles of cell by spindle fibers

16. Mitosis - Telophase Spindle fibers break down Chromosome loosens up
Nuclear envelope forms around each set of chromosomes
Cleavage furrow forms
Nucleolus forms

17. Cytokinesis Cell membrane pinches inward creating a cleavage furrow
Eventually leads to two cells

18. Cell Plate
Only in plants
Makes a cell wall