1 / 22

Mitosis

Mitosis. LH Biology – Spring 2012 Cell Division. Mitosis. Mitosis is the process where a ‘parent’ cell divides to produce two new, identical cells New cells are called ‘daughter’ cells THINK : Skin, hair, growth, and repair

sulwyn
Download Presentation

Mitosis

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. Mitosis LH Biology – Spring 2012 Cell Division

  2. Mitosis • Mitosisis the process where a ‘parent’ cell divides to produce two new, identical cells • New cells are called ‘daughter’ cells • THINK: Skin, hair, growth, and repair • New cells are produced as you grow, heal, and during day-to-day living • ALL eukaryoticorganisms produce new cells through mitosis

  3. Cell Cycle • Consists of 2 broad stages • 1. Growing Stage called Interphase • 2. Cell Division called Mitotic Phase (M Phase) • The majority of the cell cycle is spent in Interphase (90%) • Consists of 3 parts: G1, S, G2

  4. Interphase – G1 • Occurs BEFOREMitosis begins • G1 – “first gap” • Cell begins to grow • Growth continues through S Phase 2n 2n G1 Phase

  5. Interphase – S Phase • S Phase – • DNA Replication occurs • Chromosomes are duplicated (DNA copied) • Chromosomes appear as threadlike coils • Made of Chromatin, a combination of DNA and protein molecules G1: 23 mom 23 dad S: STILL 23 mom & 23 dad but DNA has been doubled

  6. Interphase – S Phase • As the cell prepares to divide, its chromatin fibers condense, becoming the compact structure we call a chromosome. • Chromosomes are copied (# doubles) • Centrosome is copied too  now TWOcentrosomes! • Each chromosome is “made” of twosister chromatidsheld together by a centromere Uncoiled chromosomes (CHROMATIN) 2 chromosomes = 4 chromatids NUCLEUS

  7. Interphase – G2 • G2 Phase (“second gap”) • G2 – Continues growing and prepares for cell division Parent chromosomes After copying, the two identical chromosomes are now called sister chromatids

  8. Refresher……. The Cell Cycle G1 phase: Growth S phase: DNA replication G2 phase: Final preparation for cell division M phase: Mitosis and Cytokinesis

  9. Mitotic Phase • After Interphase, Mitotic Phase begins • Two parts of M Phase: • Mitosis • Cytokinesis

  10. M Phase • Mitosis– the nucleus and duplicated chromosomes divide and create two identical daughter cells • Cytokinesis– the process by which the cytoplasm is divided in two • Cytokinesis usually begins before Mitosis is completed centromere cytokinesis

  11. Prophase First phase of Mitosis: • Nuclear envelope breaks down 2. Chromatin becomes tightly coiled = chromosome  condense & organize 3. Spindle begins to form in the cytoplasm (produced by the centrioles) 4. Centrosomes begin to move apart. Note: there are 2 centrioles inside each centrosome! centrosomes

  12. Metaphase Second phase of Mitosis: • Nuclear membrane disappears • Chromosomes line up in the middle of the cell forming an equator 3. Chromosomes attach to the spindle at the centromeres (belts) Note: Remember, in human cells, we have 46 chromosomes (not 4 like above…)

  13. Anaphase Third phase of Mitosis: • Spindle pulls apart the chromosomes • Chromatids separate at the centromere and move towards each end • NOTE: Each chromatid is now considered a chromosome  b/c it is no longer connected via the centromere **cell now has double the chromosomes

  14. Anaphase by the #s • When the chromosomes split at the end of metaphase, the chromosome number is doubled. • For example, the number of chromosomes and chromatids during each phase in a human cell is:

  15. Telophase Fourth phase of Mitosis: • Chromosomes reach end of spindle • Spindle breaks down • Cleavage furrow begins to form • Nuclear membrane begins to reform

  16. Cytokinesis Final Phase of Cell Division/M Phase • Cleavage furrow pinches all the way through • Result is two new cells • 2 cells then enter Mitosis & begin again! • G1, S, G2 (Interphase) • PMAT & Cytokinesis • Each new cell at the end of mitosis is DIPLOID  has a full set of chromosomes

  17. To Help You Remember…. Interphase Prophase Metaphase Anaphase Telophase Cytokinesis IPMATC IPlayMonopolyATCamp

  18. Cell division Plants vs. Animals • B/c of the cell wall found in plants, cytokinesis does not involve a cleavage furrow • During telophase, vesicles line up in the middle of the cell • Contain cell wall material • Vesicles fuse  forms the cell plate • a double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis

  19. Cell division Plants vs. Animals • Cell plate grows outward • More vesicles continue to fuse with it • Finally, the cell plate membrane fuses with the PM  two new daughter cells result • Each have their own cell wall and PM

  20. Prokaryotes - Binary Fission • Unlike eukaryotic organisms, prokaryotes produce new cells through a different process called binary fission. • Ex: bacteria • Process of Binary Fission: • 1. Duplication of chromosomes • 2. Elongation of the cell • 3. Division = two daughter cells

  21. Prokaryotes - Binary Fission • Duplication of chromosomes • DNA replication begins at the origin of replication • One copy of the DNA moves toward the opposite end of the cell

  22. Prokaryotes - Binary Fission • As DNA is duplicated, the cell is elongating • Once chromosomal duplication is complete, the bacteria is approx. twice its original size • PM has grown inward  divides parent cell into TWO daughter cells • Division is dependent on: • Nutrients available • Oxygen • On average, binary fission takes between 15-20 minutes

More Related