1. Ch 10: Cell Growth and Division

2. Cells Do not continue to grow bigger, instead they produce more cells Do not continue to grow bigger, instead they produce more cells

3. Why is this? 1. The larger a cell becomes, the more demands the cell places on its DNA (genetic material). 2. The cell has more trouble moving enough nutrients and wastes across the cell membrane.

4. Cell Division growth and repair in eukaryotes growth and repair in eukaryotes one parent cell divides into 2 new daughter cells one parent cell divides into 2 new daughter cells

5. Cell Division The parent cell passes on an exact copy of their chromosomes (located in DNA) to their daughter cells! The parent cell passes on an exact copy of their chromosomes (located in DNA) to their daughter cells!

6. What is the cell cycle? Continuous process where cells grow, make copies of their chromosomes, and divide to form daughter cells.

7. Cell Cycle has 3 Phases: 1.Interphase 2.Mitosis 3.Cytokinesis

9. The cell cycle 1 hour – several days depending on the type of cell involved. 1 hour – several days depending on the type of cell involved.

10. Cell Cycle Interphase Interphase Where most time is spent. Growth and DNA replication (copying) occur

11. Interphase 3 stages 3 stages  G1  S phase  G2

12. G1 Phase Cell grows Cell grows synthesize new proteins and organelles synthesize new proteins and organelles New cytoplasm forms New cytoplasm forms

13. S Phase Chromosomes duplicate Chromosomes duplicate

14. G2 Phase Growth continues Growth continues Prepare for mitosis Prepare for mitosis

15. Mitosis Makes up most of the “M Phase.” Makes up most of the “M Phase.” Nucleus divides into new nuclei Nucleus divides into new nuclei Each nucleus has a complete set of chromosomes. Each nucleus has a complete set of chromosomes.

16. Mitosis 4 Phases (PMAT): 4 Phases (PMAT):  Prophase  Metaphase  Anaphase  Telophase

17. Prophase Chromosomes becomes visible Chromosomes becomes visible Sister chromatids are attached at the centromere. Sister chromatids are attached at the centromere. Nuclear membrane breaks down Nuclear membrane breaks down Centrioles travel to opposite poles of the cell. Centrioles travel to opposite poles of the cell. A fanlike spindle forms around each centriole. A fanlike spindle forms around each centriole.

18. Chromosomes within Prophase carry genetic information carry genetic information consists of DNA consists of DNA cells have a specific number of chromosomes cells have a specific number of chromosomes

19. Chromosomes continued… Humans have 46 chromosomes in each cell

20. Chromatids Paired strands of a duplicated chromosome. Paired strands of a duplicated chromosome. Attached at a centrral region called the centromere Attached at a centrral region called the centromere

21. Centromere Chromatid

23. Metaphase Chromatids line up across the center of the cell Chromatids line up across the center of the cell Centromeres are attached to a spindle fiber. Centromeres are attached to a spindle fiber.

24. Metaphase

25. Anaphase Spindle fibers pull sister chromatids apart at centromeres to opposite ends of the cell.

26. Telophase Chromosomes reach opposite poles of the cell and begin to uncoil. Chromosomes reach opposite poles of the cell and begin to uncoil. Spindle breaks down Spindle breaks down Nuclear membranes reform around the chromosomes at each pole Nuclear membranes reform around the chromosomes at each pole The cell has 2 identical nuclei each with a complete set of chromosomes. The cell has 2 identical nuclei each with a complete set of chromosomes.

28. Cytokinesis Division of cytoplasm into 2 separate cells Division of cytoplasm into 2 separate cells Works different for animal and plant cells. Works different for animal and plant cells.

29. Cytokinesis Animal Cells = Central groove called a “cleavage furrow” forms in the plasma membrane and pinches the 2 daughter cells apart. Animal Cells = Central groove called a “cleavage furrow” forms in the plasma membrane and pinches the 2 daughter cells apart. Plant Cells= Involves the formation of a cell plate between the nuclei. Cell plate then transforms part of the cell wall of each new cell. Plant Cells= Involves the formation of a cell plate between the nuclei. Cell plate then transforms part of the cell wall of each new cell.

30. Cytokinesis

31. This process is found in unicellular eukaryotes and some multicellular organisms Use cell division to make NEW cells Use cell division to make NEW cells Organisms also use mitosis to REPLACE cells that are damaged or no longer useful to the organism. Organisms also use mitosis to REPLACE cells that are damaged or no longer useful to the organism.

32. For example…… Your body continuously makes new skin cells by mitosis to replace skin cells that are worn out. Your body continuously makes new skin cells by mitosis to replace skin cells that are worn out.

33. Mitosis is…. Asexual Reproduction = Production of offspring by a single parent. Asexual Reproduction = Production of offspring by a single parent. Offspring are then exact copies of their parents. Offspring are then exact copies of their parents. Examples: Yeasts and freshwater animals (Hydras) reproduce this way. Their offspring develop from buds on the parents body. Examples: Yeasts and freshwater animals (Hydras) reproduce this way. Their offspring develop from buds on the parents body.

34. Organisms that reproduce asexually

35. Cyclin protein protein regulates the timing of the cell cycle in eukaryotic cells regulates the timing of the cell cycle in eukaryotic cells

36. Regulatory Proteins Two types Two types 1.Internal Regulators 2.External Regulators

37. Internal Regulators proteins that respond to events inside the cell proteins that respond to events inside the cell signals cell cycle to continue ONLY WHEN OTHER THINGS ARE COMPLETE signals cell cycle to continue ONLY WHEN OTHER THINGS ARE COMPLETE

38. External Regulator proteins that respond to events outside the cell proteins that respond to events outside the cell direct cells to speed up or slow down the cell cycle direct cells to speed up or slow down the cell cycle example: growth regulators example: growth regulators

39. Why is cell growth regulated so carefully?

40. Uncontrolled Cell Growth Cancer Cancer body loses ability to control growth body loses ability to control growth does not respond to the regulator proteins does not respond to the regulator proteins result = large masses of cells result = large masses of cells

41. Tumors masses of cells masses of cells damages the surrounding tissues damages the surrounding tissues cells break off and spread throughout the body cells break off and spread throughout the body

43. Cause of cancer brought on by smoking tobacco brought on by smoking tobacco radiation exposure radiation exposure viral infection viral infection etc etc

44. All cancers have one thing in common…. The cell cycle has broken down