1 / 38

Cell Division

Cell Division. LG4: Understand cells’ role in living things and heredity. A Question…. What do you, an ant, and an oak tree have in common (talk to a partner)?. An Answer…. Yes, you are all living things…but more importantly You are all made of trillions of cells! AND

rubyturner
Download Presentation

Cell Division

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cell Division LG4: Understand cells’ role in living things and heredity.

  2. A Question….. What do you, an ant, and an oak tree have in common (talk to a partner)?

  3. An Answer…. Yes, you are all living things…but more importantly You are all made of trillions of cells! AND you all started out as a single cell!

  4. Cell Theory In the 1830’s Theodor Schwann & Matthias Schleiden proposed “Cell Theory”

  5. Cell Theory states… • All living things are made of cells. • Cells are the basic unit and function of all living things. • Living cells only come from other living cells.

  6. Through cell division, a single cell becomes two cells. Those two cells divide into four…. Time for math… how many cells would you have after 6 divisions? CellDivision… How do you become a multicellular organism if you started out as just ONE cell (talk to a partner)?

  7. How Many? You would have 64 cells! That’s a lot of cells!

  8. Cell Division • Cells multiply by dividing! Answer (talk to your neighbor): • How does your drawing show that cell division can cause organisms to grow larger in size? • Is there a limit to how large a cell can be? Why or why not?

  9. Consider…. What are the purposes of cell division? • Regrowth/growth • Repair • Reproduction (Hint: This is important!)

  10. Regrowth/Growth How tall were you when you were 5? How tall were you last year? How tall are you now? Do you think: Your cells got bigger? or Your cells divided to produce more cells? (talk with a neighbor)

  11. Regrowth • While individuals grow in size, a larger organism has MORE CELLS than a smaller organism • There arelimits on how big a cell can get. What do you think is the main reason why cells only get to be a certain size?

  12. Regrowth Cells continue to divide to help an organism or part of an organism grow As the cell grows, more processes are needed for it to function, so its demand for instructions increases. However, the amount DNA (instructions) remains constant. The instructions will determine what type of cell it becomes.

  13. Specialization We know that cells divide in order to make bigger organisms. However, if cell division were the only process occurring in cells, all multicellular organisms would end up as spheres of identical cells. During development, cells become specialized to perform particular functions.

  14. In Other Words…. Cells get instructions from DNA about what type of cell it will become and what will be its function! COOL!

  15. Cell Types Some cells might become layered skin cells, while others might become long, thin nerve cells. Cheek Cells Nerve Cells Red Blood Cells Bone Cells

  16. One purpose of cell division Regrowth Next reason…

  17. Repair Have you gotten a paper cut recently? Have you broken a bone in your arm or leg?

  18. Repair • The body repairs injuries like these by means of cell division. For example……. When your skin is cut, skin cells on either side of the cut make new cells to heal the wound.

  19. Repair • As cells age and die, they need to be replaced. In the human body: -There are about 200 different types of cells (remember the pictures?). -Every minute or so, your skin loses about 40,000 cells! -In contrast, your brain cells live a very long time!

  20. One purpose of cell division Regrowth Next reason…

  21. Reproduction • In order for organisms to reproduce, reproduction (sex cells – meiosis) must occur • Reproductive cell division produces sex cells with ½ the genetic information from each parent (humans – 23 from mom / 23 from dad)

  22. Summary… • Cells are the main components of all living things • The purpose for cell division: • Regrowth • Repair • Reproduction

  23. Cell Cycle

  24. The Cell Cycle Mitosis in Words Interphase Cell grows, makes a copy of DNA. (90% of cell’s life is spent here!) Cytokinesis Prophase Chromosomes and spindle fibers form; nuclear envelope breaks down. Cell membrane pinches in two; each daughter cell has same number of identical chromosomes. Metaphase Telophase Chromosomes line up across the center and attach to a spindle fiber. Chromosomes stretch out; new nuclear envelope forms around chromosomes. Anaphase Centromeres split; chromatids separate and move to opposite ends.

  25. Length of the Cell Cycle

  26. Mitosis

  27. One More Look at Mitosis

  28. Meiosis (“my-o-my! Sex Cells!) • The process by which the number of chromosomes is reduced by half to form sex cells (sperm and egg) • Chromosome pairs separate and are distributed to two different cells. • The resulting sex cells have only half as many chromosomes as the other cells in the organism.

  29. Meiosis • Requires two divisions of the nucleus • Meiosis I- (Just like mitosis) • Meiosis II- two daughter cells go through a second division of the nucleus. (during this process, there is no chromosome replication) Meiosis II (after Meiosis I which is Mitosis)

  30. The difference between Mitosis and Meiosis(W.U. - copy this slide into notes)

  31. Cancer is Uncontrolled Mitosis: • Mitosis must be controlled, otherwise growth will occur without limit (cancer) • Mutations in control • proteins can cause cancer

  32. Cancer is a disease in which cells grow and divide uncontrollably, damaging the parts of the body around them. It is caused by a mutation that causes uncontrolled mitosis. Cancer Cells – What is it?

  33. Mutations • A mutation (from Latin word that means change) is any change in a gene or chromosome. • Can cause a cell to produce an incorrect protein during protein synthesis. • As a result, the organism’s trait, or phenotype, may be different from what it normally would have been.

  34. Results of Mutations • If a mutation occurs in a SEX CELL, the mutation can be passed on to an offspring and affect the offspring’s phenotype. • If a mutation occurs in a BODY CELL, the mutation will not be passed on to the organism’s offspring.

  35. Effects of mutations • Introduce change in an organism (genetic variation) • Can be harmful (reduces the organism’s chance for survival and reproduction) • Can be helpful (improve an organism’s chance of survival and reproduction) • Antibiotic resistance in bacteria • Can be neither harmful nor helpful

  36. Rate Yourself! LG4: Understand cells’ role in living things and heredity. “Before this presentation, I was a _____ (scale rating 0-4) because I knew __________ about cells. now, I feel like I am a _____ (scale rating 0-4) because I learned

  37. Cells are Cool!

More Related