1. DO NOW

2. Cell Cycle & Cancer Review

3. EQ: How does mitosis result in two identical daughter cells.
16.4- Explain the stages of mitosis in the formation of new cells and its importance in maintaining chromosome number during asexual reproduction

4. Sexual vs. Asexual Reproduction
Combining genetic material from two different individuals of different sexes
Results in genetically different organisms
Uses Gametes (Sex Cells)
Sperm & Egg
Haploid = A cell or organism consisting of one set of chromosomes (half)
In humans, the haploid number is 23 (egg=23, sperm=23)
Symbolized as n 
Think “hap” like Half!

5. Sexual vs. Asexual Reproduction
One organism makes an EXACT copy of itself.
Results in genetically identical organisms.
Occurs in Somatic Cells (body cells)
Diploid = A cell or an organism consisting of two sets of chromosomes 
In humans, the diploid number is 46 (23 from mom, 23 from dad)
Symbolized as 2n 
The prefix “di” means…

6. The Cell Cycle The following steps are included in the cell cycle :
Interphase G1 S G2
Mitosis: Part of the cell cycle where the nucleus of the cell divides into two. 
4 Stages
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis 

7. Multicellular Organisms Unicellular Organisms
Growth 
Repair
Development
Occurs in somatic (body cells) 
 Unicellular Organisms 
Asexual Reproduction 
No genetic variation
Prokaryotes (bacteria) 
Called Binary fission (no nucleus) 
Purpose of Mitosis 
Result for Both: 2 New IDENTICAL Cells with the same number of chromosomes

8. Overview of mitosis I.P.M.A.T. Please Make Another Two Cells
interphase
prophase
(pro-metaphase)
Please Make Another Two Cells
cytokinesis
metaphase
anaphase
telophase

9. Review! Interphase 90% of cell life cycle
cell doing its “everyday job”
Nucleus well-defined
DNA loosely packed in long chromatin fibers
Prepares for mitosis
grows
replicates chromosome
DNA & proteins
produces proteins & organelles

10. Chromosome Structure
Chromatin - uncoiled
Chromatid
Sister Chromatids
DNA replicates
Chromatin - spaghetti structure of DNA to form chromosomes
during interphase
Centromere- hold the sister chromatids together (CENTER) to form the chromosome
Chromatid – half of the Chromosome
Chromosome: a condensed, continuous strand of DNA , “X”
During mitosis
Humans have 46 chromosomes

11. Mitotic Chromosome Duplicated chromosome 2 sister chromatids
narrow at centromeres
contain identical copies of original DNA
Homologous duplicated
chromosomes
homologous
chromosomes
Homo = same
Logos = word or plan
sister chromatids
single-stranded
double-stranded
homologous = “same information”

12. Summarizing…
DNA coils around histone proteins, forming chromatin; chromatin coils around organizing proteins to form chromatids, which yields highly condensed chromosomes

14. Check for understanding
Why do we copy the DNA for mitosis?
Why do we copy the DNA during interphase and not mitosis?
Why is it called mitosis for multicellular organisms and binary fission for unicellular organisms?
Now we are done with Interphase and our cell is ready for MITOSIS!

15. Mitosis – Essential Vocabulary
Centrioles
animal cells ONLY!
Help coordinate cell division
Spindle fibers
elongations of the centrioles
form the mitotic spindle.

16. Overview of mitosis I.P.M.A.T. Please Make Another Two Cells
interphase
prophase
(pro-metaphase)
Please Make Another Two Cells
cytokinesis
metaphase
anaphase
telophase

17. Prophase Pack up! (prophase) cell nucleus
Chromatin condenses into duplicated chromosomes
visible chromosomes
Chromatids
DNA is wound up into chromosomes to keep it organized
Nuclear envelope breaks down
Centrioles move to opposite sides of the cell.
nucleus
cell
duplicated chromosomes
Pack up!
(prophase)

18. Why would this be important?
Metaphase
Chromosomes align along middle of cell
metaphase plate
meta = middle
spindle fibers coordinate
movement
helps to ensure
chromosomes separate
properly
so each new nucleus
receives only 1 copy of
each chromosome
Why would this be important?
Middle
duplicated chromosomes
lined up in middle of cell
(metaphase)

20. Anaphase Away or Apart (anaphase) Sister chromatids separate
move to AWAY opposite poles
pulled APART at centromeres
Start moving to opposite ends (no longer attached)
Poles move farther apart
cell lengthens (gets bigger/longer)
Away or
Apart
chromosomes split & move to opposite ends
(anaphase)

21. Separation of chromatids – not in notes…just a visual
How is the structure of the chromosome related to it’s function?
In anaphase, proteins holding together sister chromatids are inactivated
separate to become individual chromosomes
1 chromosome
2 chromatids
2 chromosomes
single-stranded
double-stranded

22. Telophase Two Nuclei! (telophase) Chromosomes arrive at opposite poles
Nucleus forms again
Chromosomes unwind into chromatin
no longer visible under light microscope
Spindle fibers withdraw
Two Nuclei!
(telophase)

23. Cytokinesis Cut (into 2 cells) (cytokinesis)
Cells cytoplasm divides to form two identical cells
DNA unwinds
now they can do their every day jobs
Different process in plant and animal cells
Cut
(into 2 cells)
Cyto = “cell”
Kinesis = “movement”
(cytokinesis)

24. Cytokinesis in Animals
Constriction belt around equator of cell
Forms cleavage furrow
splits cell in two
like tightening a draw string

25. new cell wall laid down between membranes
Cytokinesis in Plants
cell plate forms
new cell wall laid down between membranes
new cell wall fuses with existing cell wall

26. Result 2 New “daughter” cells for plant or animal cell
Get 2 exact copies of original cells
same DNA
“clones”
Why is it important in mitosis that the two new cells produced have the same DNA as the parent?

27. Name That Phase! 
What did the cell say to his sister when she stepped on his toe? “Ouch! Mito-sis!”
METAPHASE
TELOPHASE
ANAPHASE
PROPHASE

28. Any Questions??

29. Mitosis Cut Outs! Chromosomes (Chromatids & Sister Chromatids) = Blue
Step 1: Identify and label the phase of mitosis
Step 2: Use the following key to color your cut outs:
(copy this key onto your handout)
Chromosomes (Chromatids & Sister Chromatids) = Blue
Centromere = Orange
Spindle fibers = Red
Centrioles = Yellow
Nucleus and Nuclear Envelope = Purple
Step 3: Cut out and place in the correct order on a sheet of loose leaf paper.
Step 4: Label each phase with its correct name and one word that describes what is occurring during that stage.