Mitosis: The Process of Cell Division in Eukaryotes

1. Mitosis (cell division)

2. Eukaryotes Cells that have a nucleus and membrane-bound organelles, like… Mitochondria Ribosomes ER Golgi Apparatus

3. Nucleus Nucleus= Boss of the cell Contains DNA= the code of life

4. Why must cells divide? • All living things contain cells • Cells die and sometimes we need to make more. (We grow, get hurt, fight diseases, etc.) • Cells are specialized to perform different functions Hearts are made of… Surprise! Heart cells

5. Why are cells so small? • Three things limit cell size: • DNA overload – the amount of DNA is always the same in a cell, as the cell grows larger there are more things to control and not enough DNA • Surface Area: Volume Ratio (and how this affects Diffusion)

6. Cells have to divide into new cells…How does mitosis help us? • Cell division (mitosis) helps us.. • Grow • Repair wounds and damaged cells • Develop and change

7. How does mitosis work? • How do cells divide? Great question! • So we need one cell to form two new identical cells… • What do we need to do first? • Grow in size • Replicate our DNA • Double our organelles and check and make sure everything is OK to start cell division (mitosis)

8. Mitosis • Mitosis: The process by which the nucleus of a cell is divided into two new ones! • Each daughter cell ends up with the same number and kinds of chromosomes as the parent cell!

9. Cytokinesis • Division of the cytoplasm (after mitosis!)

10. DNA • Deoxyribonucleic acid • During mitosis, DNA gets reorganized from messy, spaghetti-like CHROMATIN into organized, neat CHROMOSOMES! • Humans have 46 chromosomes (23 from your mom, 23 from your dad)

11. Chromosome number Just the way the DNA is packaged! How many do certain organisms have?? Amoeba= 50 Cat = 32 Goldfish =94 Earthworm= 36 Human = 46

12. Chromosomes • Chromosomes are made up of material called chromatin • Chromatin= DNA and protein coils • Protein= spool • DNA= Thread

13. Neat & tidy chromosome Relaxed chromatin

14. Chromosome structure • After DNA replication the chromosomes become visible by condensing. This is the beginning of mitosis Chromosomes = 2 sister chromatids and a centromere holding them together (see next page!)

15. Chromosome

16. Mitosis Basic Cell Reproduction Basic Cell Reproduction

18. Cell Cycle= interphase and mitosis • Interphase= the “getting ready” period between cell divisions. Contains G1, S, and G2 • G1= Gap one phase. Cell grows to be able to divide. • S Phase= DNA synthesis • G2= Gap two phase. More growth! Specifically, the growth of new cell organelles and materials required for cell division

19. Mitosis Basic Cell Reproduction

20. Mitosis 4 stages: • Prophase • Metaphase • Anaphase • Telophase PMAT!

21. Mitosis • During prophase the DNA condenses into chromosomes • Centrioles in animal cells help in lining up the chromosomes and forming the spindle

22. Prophase • Centrioles move to opposite sides • The nuclear envelope breaks down • Chromatin condenses into chromosomes

23. Metaphase • Meta = middle • The chromosomes line up in the middle of the cell • Spindle forms and connects to each chromosome

24. Anaphase • The centromeres that join the two chromatids split and they start to pull apart from each other

25. Telophase • Chromosomes unwind to form chromatin • Nuclear envelope reappears • Cytoplasm begins to pinch apart • Spindle breaks down See how it’s kind of the opposite of Prophase??

26. Cytokinesis • After mitosis (nucleardivision) the cytoplasm of the cell divides • A cell membrane forms, separating the two new cells

27. Let’s look at that again…

28. Early Prophase

29. Late Prophase

30. Early Metaphase

31. Late Metaphase

32. Anaphase

33. Telophase