Chapter 6 Mitosis

Last step in the cell cycle is Mitosis One cell splits and becomes two Linking Growth & Duplication 2

Mitosis Stages of Mitosis Animals vs. Plants Asexual reproduction 3

Centrioles Responsible for separation of chromosomes – During mitosis 4 Found only in animals Cytoskeleton formation & organization – Including mitotic Spindle

5 Aster – binds centriole to membrane to pull apart chromosomes

Mitosis 6

Mitotic Stages The 5 Stages of Mitosis are: Prophase Metaphase Anaphase Telophase Cytokenesis 7

1. The end of G 2 Chromatin has been duplicated Organelles have been duplicated, including centrioles The Cell has undergone enough growth to divide All systems go to divide!!! 8

2. Prophase The Chromatin coils In to Chromosomes – Sister chromatids attached at the centromere The Centrioles move apart forming a microtubules lattice called the Mitotic Spindle – Microtubules from each centriole catch the sister chromatids The nuclear membrane breaks apart 9

3. Metaphase All the chromosomes line up along an imaginary mid-line called the metaphase plate Every pair of chromosomes are pulled in line – Microtubules from each centriole catch every pair of chromatids at Kinetochore 10

The Metaphase Plate Imaginary Plane on which chromosomes line-up before separating 11

4. Anaphase The connection between chromatids breaks down The sister chromatids are pulled to opposite centromeres Microtubules not connected to a chromosome push – cause the cell to elongate 12

13 Microtubule Motor Protein Chromosome Movement

5. Telophase The nuclear envelopes being to re-form around the two separate sets of DNA – Two nuclei The mitotic spindle breaks down A set of microfilaments being to form between the two nuclei – Divide the remainder of the cell in two 14

6. Cytokenesis and Cleavage Microfilaments Contractile Ring Constricts creating a Cleavage Furrow – Will eventually separate the two cells Cytokinesis – the division of cytoplasm 15

Cytokinesis in Animals The contractile ring pinches off the cell membrane between the two daughter cells Cleavage furrow forms along the metaphase plate 16

Mitosis in Plants Mitotic stages the same 1.Plants lack centrioles – so microtubules connect to membrane/cell wall at opposite poles 1.Formation of the cell plate during cytokinesis 17

Cytokenesis in Plants Cell Plate forms between the nuclei – Cellulose Cell plate extends to the parental cell wall – Cell membrane reforms along the cell plate 18

Cytokenesis in Plants 19

Growth in Plants 20

Apical Meristems 21

Cytokenesis in Bacteria Called Binary Fission DNA replicates – Copies move to opposite ends of the cell Cell wall and membrane extend Cell wall pinches off between cells 22

Cytokenesis in Bacteria 23

Unicellular Asexual reproduction One cell becoming two daughter cells Each become a separate organism 24 (Binary Fission)

Asexual Reproduction Budding Occur in unicellular and some multicellular organisms 25 Offspring from a single parent – Clones – Genetically identical to parents

Multicellular Asexual Reproduction 26

Worlds Largest organism through Asexual reproduction The Honey Mushroom Armillaria ostoyae 2384 acres (~1665 football fields) Outcrops of fruiting bodies found across this area used to determine size – Maintain underground connections 27

Review What is the goal of mitosis? – What is the genetic relationship of the daughter cells? How does Mitosis differ in Plants, Animals, and Prokaryotes (Bacteria)? – How is it similar? 28

Review Produce two identical daughter cells Method of cleavage – Animals – Cleavage Furrow – Plants – Cell Plate – Bacteria – Binary Fission 29

Questions How many copies of DNA must a cell have just before dividing? 30

Questions Cells must have to copies of DNA, so they can be separate equally Copies of DNA are attached to each other as Sister Chromatids – Which seperate during mitosis 31