Chapter 8 Cell Growth and Division

1. Chapter 8Cell Growth and Division Biology

2. 10-1 Cell Growth • Adults don’t have bigger cells than kids… they just have MORE of them

3. Why don’t cells just grow bigger? • DNA overload….DNA would need extra copies to handle “information demand” • Too difficult to get enough nutrients and oxygen IN and waste products OUT

4. The world's tallest man in 2007 7’9”, Bao Xishun and his 5’6” wife… • most peoplewith acromegalic gigantism eventually die because of complications fromheart problems. • "Keeping the blood going round such an enormous circulationbecomes a huge strain for the heart,"

5. What would happen?Calculate ratio of surface area to volume • L * W * # of sides= surface area • L * W * H= Volume • Practice problem: if cell was a cube and its sides were 1cm each ….figure SA? • Figure V… • What if the cell were 3cm? SA? V? • What is the ratio?

6. Volume increases faster than surface area • 1*1*6=6 SA • 1*1*1=1 V • Ratio 6:1 • 3*3*6=54 SA • 3*3*3=27 V • Ratio 54:27 reduce… 2:1 • The decrease in ratio of SA to V- makes it harder for the cell to move needed products in and out.

7. Cell division solves… • The problem of information storage… because each daughter cell gets it’s own DNA • The problem of being too big and inefficient because although the cell grows some… daughter cells will still be smaller than the parent

8. 10-2 Cell Division : is mitosis4 sections of the cell cycle: G phases, S phase, mitosis, cytokinesis

10. In Bacteria …prokaryotes • Have circular DNA • And only 1 piece of DNA called plasmid • The process by which bacteria reproduce is called binary fission (not mitosis)

11. 10-2 Cell Division • In eukaryotes the chromosomes carry the genetic information and they live inside the nucleus • Chromosomes are made up of DNA and proteins (called histones)

13. Centromere is made of proteinSpindle fibers are made of microtubulessister chromatids are duplicate halves

14. Karyotype- • Tells # of chromosomes in that body cell

17. Growth & Repair

19. Interphase • Baby Cell (daughter cell) grows and matures here…and eventually is mature enough to divide • a.k.a.…time in between cell division

21. 3 steps of Interphase • G1- cell grows, and makes new proteins and organelles • S phase- DNA is replicated • G2- molecules and organelles needed for cell division are produced.

22. Now ready for MitosisPMAT • Prophase- • longest, • chromosomes become visible/ • centrioles go to the poles • Spindle fibers start to form • Nuclear envelope starts to break down

24. Mitosis…. • Metaphase (middle) • Last only a few minutes • Chromosomes line up across the MIDDLEof the cell • Centromeres connect to the spindle fibers

26. Mitosis… • Anaphase (the fingers) • Centromeres split , splitting chromosomes into 2 sets • Chromosomes move away from each other to the poles- being pulled by spindle fibers

28. Mitosis • Telophase (the peanut) • Chromosomes begin to disappear from view • Nuclear envelope re-forms • Spindles break apart • Nucleolus reforms • …end mitosis

30. Cytokinesis Cell plate > • Nucleus and contents have split but what about the rest of the cell….? • Cell membrane is drawn inward until cytoplasm is eventually pinched into two equal parts • In plants cell plate eventually becomes the cell wall

31. http://www.biostudio.com/d_%20Mitosis.htm

32. 10-3 Regulating the Cell Cycle • Cell growth and cell division are carefully controlled • Cells grow when there is space , then when they bump into other cells they stop • A cut in your hand?

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34. What signals the cell to start dividing? • A set of proteins called cyclins control the timing of cell division… • Internal Regulators- tell cell to divide based on what is happening inside the cell (PMAT timing) • External Regulators- tell cell to divide based on what is happening outside the cell (wound healing , embryonic development)

35. Cancer • A disorder in which some of the body’s own cells (whose DNA is damaged) lose the ability to control growth… • Cells grow out of control and form masses called tumors • Sometimes these cells break free and spread throughout the body • These cells lack the proteins that tell them to stop growing and ignore the bordering cells telling them to stop

36. Causes of Cancer • Viral Infection (commercial) • Radiation (sun, x-rays ) • Smoking tobacco • Anything known to cause cancer cells to develop is called a carcinogen….

37. Identifying the Number of Chromosomes… • Not all living things have the same number of chromosomes.. • Humans: 46 • Fruit flies: 8 • Carrots: 18 • **worksheet

38. Haploid vs Diploid • Haploid: half • Diploid: Double • But first figure out where you are at? • Body cell(regular cell) is already Diploid • Sperm/egg cell (sex cell) is already Haploid

39. Differences between animal and plant cells- • Plants have a cell wall and a cell membrane- so when they pinch…it’s called a cell plate. • The cell plate becomes the cell membrane – then the cell wall develops next. Cell plate >

41. The End…