1. The Life of a Cell

2. Cells have a lifecycle Cells live and function. Cells need to reproduce –To replace old cells –To replace injured cells –In order for living things to increase in size –In order for living things to develop Cells die

3. Some cells live longer than others –Red blood cells live approximately 10 days –Stomach and cheek cells live less than a day –Most nerve and brain cells live your entire life Therefore, cells must be able to reproduce

4. The Life of a Cell G1, S, G2 are known as Interphase M stands for Mitosis

5. Interphase 3 phases in Interphase G1 phase –Cell grows larger –Performing cell functions (doing its job) S phase –DNA Replication G2 phase –Performing cell functions (doing its job)

6. The importance of replication Replication MITOSIS Each new cell needs the same information as the original cell or it won’t function properly

7. So what do chromosomes look like after replication? Single chromosomes BEFORE AFTER Chromosome and its copy

8. Closer Look The two replicas are connected at a center called the centromere (centro………center) Each replica is referred to as a sister chromatid

9. Steps of Mitosis Prophase Metaphase Anaphase Telophase

10. Prophase Chromatin (a mass of DNA and histones) wraps into chromosomes (you now begin to see chromosomes- they will look like thick fingers) You can’t see chromosomes here Just 2 nucleoli Now you can see dark fingers These are chromosomes

11. Prophase Nuclear membrane starts to disappear Centrioles start to move to opposite sides of cell centrioles

12. Metaphase When you think Meta think Middle! Chromosomes line up in center of cell Spindle fibers connect to each chromosome Spindle fibers come from the centrioles (think of them like strings) Spindle fibers

13. Anaphase Spindle fibers shorten and pull the chromosomes Chromosome break in half and move to opposite sides of cells Notice: no more sister chromatids, each one is now a chromosome

14. Telophase Nuclear membrane returns Cytokinesis occurs (cytoplasm and organelles are divided)

15. Interphase and Mitosis in Plant Cells NAME THE PHASES

16. How will we remember this? Let’s do the hand

17. So here is the complete cell cycle

18. Grab your microscope and let’s see if you can find the phases At the lab, go to this powerpoint. You may work in groups of 2, but make sure each person sees!!!! The rest of the power point will walk you through how to find the correct cells You must draw each phase as you see it and obtain a signature from me for points. Oh joy, what fun we’ll have

19. Root Tip Under the Microscope

20. 3 Labeled Areas Elongation zone: What phase do you think these cells are in? Why? Interphase, they are growing larger and functioning Root Cap: These cells are old and will be damaged and dead. They are the ones that are pushed through the dirt as the root grows. (similar to dead skin)

21. Where to look for this lab Find the root on scanning power first. Find the root cap. Move to the zone of mitosis. Go to low power, make sure you are still in the middle of the zone of mitosis FOCUS!! Move to high power

22. Interphase Look for the nucleus and nucleolus!!

23. Prophase You should be looking for the dark fingers (chromosomes)

24. Metaphase Meta…Middle Chromosomes should be in a line down the middle of the cell

25. Anaphase Centromeres have broken and fibers are pulling the chromosomes to opposite sides of the cell

26. Telophase/Cytokenesis Starting to look like there is a nucleus again. Look for a new cell wall forming between the two new cells. There’s that new cell wall

27. Mitosis in Animal Cells Follow this link to see an animation and a real animal cell undergoing mitosis Can you tell when the real cell hits the various stages or do they seem to blend into each other? Mitosis: An Interactive Animation

28. Still Frames of Mitosis in Animal Cells Look at the phases in animal cells and note any differences on your paper Animal cell Mitosis phases

29. Have a nice day!