1 / 23

Why do cells need to divide?

Why do cells need to divide?. How do cells divide? What needs to happen to make an exact copy of this cell? . Does an organism grow because its cells get larger or because it increases the number of cells? What limits the size that a cell can reach?

airell
Download Presentation

Why do cells need to divide?

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. Why do cells need to divide?

  2. How do cells divide? What needs to happen to make an exact copy of this cell?

  3. Does an organism grow because its cells get larger or because it increases the number of cells? • What limits the size that a cell can reach? • How does the surface area change when a large cell divides into smaller cells that have the same total volume? • Are cells dividing all the time? • Do all cells divide at the same rate? • What must duplicate/replicate before a cell divides?

  4. Types of Reproduction • Asexual Reproduction • Cloning of an individual cell • Produce genetically identical offspring • Occurs in bacteria, body cells • Sexual Reproduction • Occurs when two reproductive cells join • Make genetically diverse cells since the offspring get traits from both parents

  5. Vocabulary Chromatin- long strand of DNA Chromatid- each strand of a duplicated chromosome Centromere- the area where two chromatids are joined. Splits during anaphase. Kinetochore- a protein on chromosomes where spindle fibers attach.

  6. Centrioles- tiny structures in the cytoplasm of animal cells that help organize the spindles. (2 centrioles =centrosome) Spindle fiber- a fanlike microtubule structure that helps separate the chromatids

  7. Spindle- a fanlike microtubule structure that helps separate the chromatids -composed of centrioles and spindle fibers

  8. Cell Cycle- Interphase • G1 – Cell Growth-increase in size, routine functions (longest) • S – DNA replication- Synthesis of new DNA/ chromosomes replicated • G2- Preparing for Cell Division- replication of organelles, microtubules and other molecules for cell division

  9. http://iknow.net/cell_div_education.html

  10. M Phase (minutes to days) • Mitosis • Prophase • Metaphase • Anaphase • Telophase Pro=before Meta=after Ana=back Telo= end • Cytokinesis • Division of the cytoplasm and organelles

  11. Mitosis- phases • Prophase • Chromosomes become visible (coil) • nuclear membranedissolves • Spindle forms • Nucleolus disappears

  12. Prophase

  13. Metaphase • Chromosomes line up along the equator • Spindle fibers connect centromeres (of chromatids) to opposite poles

  14. Anaphase • Centromeres divide • Chromosomes move toward opposite poles • Each Sr. Chromatid is pulled toward opposite pole • Spindle fibers shorten

  15. Telophase • Reverse of Prophase • Nuclear membrane forms at each pole • Chromosomes uncoil • Spindle fibers dissolve • Cytokinesisbegins

  16. Cytokinesis • Cytoplasm divided in half • Cell membrane pinched by a belt of protein threads or contractile ring

  17. Plant vs Animal Cell Division Animals Plants No centrioles Vesicles fuse forming a cell plate A new cell wall forms on either side of the cell plate • Centrioles • Pinching or cleavage of cell membrane Both Equal sized offspring cells Identical copy of original cell’s chromosomes

  18. Animal and Plant Cell Division • http://iknow.net/cell_div_education.html

  19. Prophase- a “pro” is #1 • Metaphase- “M” middle • Anaphase- Away • Telephase – Two nuclei

  20. http://glencoe.mcgraw-hill.com/sites/dl/free/0078802849/164155/00053413.htmlhttp://glencoe.mcgraw-hill.com/sites/dl/free/0078802849/164155/00053413.html

More Related