1 / 8

Cell Cycle

Cell Cycle. Repeating cycle of growth and division Interphase —takes up ~ 80% of cell’s life; 3 phases G1 —cell is rapidly growing and carrying out routine functions (longest) S —synthesis phase when DNA replicates from a single chromatid into a full chromosome

hetal
Download Presentation

Cell Cycle

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 Cycle • Repeating cycle of growth and division • Interphase—takes up ~ 80% of cell’s life; 3 phases • G1—cell is rapidly growing and carrying out routine functions (longest) • S—synthesis phase when DNA replicates from a single chromatid into a full chromosome • G2—organelles replicate and chemicals needed for mitosis are produced and sent to proper locations within the cell

  2. Cell Division and Mitosis • When a cell becomes too large to function properly due to surface area-to-volume ratio it will be stimulated to divide • Prokaryotic cells (bacteria) undergo binary fission: asexual reproduction that produces identical daughter cells • Can occur every 20 minutes!! • First the single circular strand of DNA replicates, then the cell divides into 2 cells that are identical in every way—think “cloning”!

  3. Eukaryotic Mitosis and Cell Division • Due to all the organelles in eukaryotes, process more complex • Mitosis—nuclear division—nucleus divides into 2 identical nuclei; made of 4 phases • Replaces old cells in an organism • Replaces damaged cells • Remembered by the acronym: PMAT • Occurs only in somatic cells—gametes are a whole another process!

  4. P = Prophase • Chromosomes begin to condense into fuzzy X’s and are visible under a light microscope • Nuclear membrane starts to dissolve • Centrioles start to move apart to opposite sides of cell • Spindle fibers (protein microtubules) form between centrioles—these fibers help pull the chromosomes apart later • Plants do not have centrioles, but they do have spindle fibers

  5. M = Metaphase • Second set of spindle fibers extend out from each chromosome’s centromere—2, one in each centriole direction • Grow until they reach the first set of spindle fibers • Spindle fibers line the chromosomes up at the center (equator) of the cell

  6. A= Anaphase • Centromeres divide and the 2 chromatids separate • Spindle fibers shorten and the chromatids move toward opposite sides of the cell • Looks like centrioles are reeling them in as if fishing!

  7. T = Telophase • Chromatids undergo name change and are now called chromosomes again • Chromosomes start to uncoil at opposite sides of cell • New nuclear membranes form around them • Spindle fibers break and dissolve

  8. Cytokinesis • Cell then starts to divide: cytoplasm is split into 2 new cells • In animals a cleavage furrow forms between the nuclei—cytoplasm is pinched in half • In plants vesicles (created by Golgi bodies) fuse at center of the cell and form a cell plate • New cell wall is created on either side of the plate • In both plants and animals, the 2 new cells each have their own organelles (formed during G2)

More Related