1. Cell Reproduction/Mitosis
Chapter 8

2. What you need to know!
Mitotic Cell division results in genetically identical daughter cells
The mitotic phase alternates with interphase in the cell cycle

3. Cell Division Life depends on the ability of cells to reproduce/copy
Cell Division = 1 mother cell divides into 2 daughter cells
Unicellular organisms cell division = reproduction
Prokaryotes, Protists
Bacteria = binary fission

4. Cell Division
Multicellular organism cell division = growth and development, repair and replacement
Protists, fungi, plants and animals
2 categories of cells:
Somatic Cells: Body cells of an organism that do all the daily function of the organism (mitosis)
Germ Cells: reproductive cells like eggs and sperm (meiosis)

5. Cell Cycle Interphase Mitosis (M): nuclear division
G1: Growth, development, organelle production, etc.
S: DNA replication
G2: continued growth and preparation for division (centrosomes/centrioles duplicate)
Mitosis (M): nuclear division
Cytokinesis: cell splits into two cells

6. DNA Chromatin (spaghetti): spread out DNA-histone complex
Chromosome (X’s): condensed strands of DNA

7. DNA Diploid indicates somatic (body) cells
Humans have 23 pairs of chromosomes (2n)
Haploid indicates gametes (sex cells)
Humans have 23 chromosomes (1n or n)

8. Mitosis: Nuclear Division
Each chromosome contains thousands of genes, each necessary to the proper functioning of the organism.
Humans have ~120,000 genes spread over 46 chromosomes in each somatic cell.

9. Mitosis
During Mitosis all access to the DNA stops as chromatin coils up and condenses into visible chromosomes
Each replicated chromosome is composed of 2 identical parts (sister chromatids) held together by a centromere

10. Mitosis
Sister chromatids are pulled apart during mitosis, and partitioned into 2 daughter cells
Result of mitosis & cytokenesis: 2 daughter cells genetically identical to the parent cell.

11. Phases of Mitosis
Prophase: Chromosomes condense; centrosomes are pushed apart by growing spindle fibers; nuclear envelope disintegrates

12. Stages of Mitosis
Prometaphase: the 2 centromeres of each chromosome attach to one kinetochore spindle fiber; centrosomes move to opposite poles
Kinetochore spindle fiber
Non Kinetochore spindle fiber

13. Stages of Mitosis
Metaphase: Chromosomes line up at the metaphase plate (equator); centrosomes are at opposite poles

14. Stages of Mitosis
Anaphase: Chromosomes separate (shortening of kinetochore spindle fibers); cell elongates (lengthening of non-kinetochore spindle fibers)
Non Kinetochore spindle fiber
Kinetochore spindle fiber

15. Stages of Mitosis
Telophase: Chromosomes immediately uncoil and resume transcription activities; spindle proteins disassemble; nuclear envelope reassembles

16. Mitosis Animation

17. Cytokinesis Animal Cells: Cleavage furrow
Made by microfilaments (actin fibers)
A drawstring around the middle of the cell
Cell pinches off into 2 daughter cells
Plant Cells:
No cleavage furrow
Cell plate grows through divided cell