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					Mitosis

Section 8.2
                 Objectives
• Describe the four stages of mitosis

• Describe the structure of chromosomes

• Differentiate what happens during Cytokinesis
  in plant and animal cells
                  Mitosis
• Instructions for making new cells are in
  DNA
• Chromatin – long strands of DNA in the
  nucleus of a cell
                    Mitosis
• Chromatin coils up to form chromosomes
• Chromosomes carry genetic material
  – Passed from generation to generation
                 Mitosis
• The two halves of a doubled chromosome are
  called sister chromatids




                             Sister
                           chromatids
                   Mitosis
• Sister chromatids are held together by the
  centromere




   Centromere                   Sister
                              chromatids
                    Mitosis
• Accurate transmission of chromosomes is
  critical

• The identity of a cell is determined by
  chromosomes
                    Mitosis
• During interphase
  – Chromatin (DNA) has been copied
  – Cell parts have been made


• Cell has everything it needs to divide
                    Mitosis

• Animal cells in
  interphase
                    Mitosis
• Mitosis is the phase when cells divide
  – Occurs as cells reach their maximum size
• There are four distinct stages of Mitosis
  – Prophase
  – Metaphase
  – Anaphase
  – Telophase
                    Mitosis
• Prophase
  – Chromatin coils up to form visible doubled
    chromosomes




Doubled
chromosomes
                    Mitosis
• Prophase
  – Nuclear envelope begins to disappear




Nuclear
envelope
                     Mitosis
• Prophase
  – Spindle fibers begin to form




 Spindle
 fibers
                   Mitosis

• Animal cell in
  prophase
                    Mitosis
• Metaphase
  – Spindle fibers attach to the centromeres
  – Chromosomes move to the equator
                    Mitosis

• Animal cells in
  metaphase
                  Mitosis
• Anaphase
  – Spindle fibers shorten
  – Chromosomes separate at centromeres
                    Mitosis
• Anaphase
  – Only one chromatid goes to each daughter cell!
                    Mitosis

• Animal cells in
  anaphase
                     Mitosis
• Telophase
  – Nuclear envelope reforms




Nuclear
envelope
reappears


            Two daughter cells are formed
                    Mitosis

• Animal cells in
  telophase
The Stages of the Mitotic Phase




        Interphase   Prophase     Prophase (late)




       Metaphase     Anaphase


                                    Telophase
                    Mitosis
• Cytokinesis
  – Not considered part of mitosis
  – Cytoplasm divides and cells separate


• Different in plants and animals
                  Mitosis
• In animal cells the plasma membrane pinches
  along the equator
                 Mitosis
• In plants a cell plate forms
• Plasma membrane and cell wall forms around
  plate
                    Mitosis
• At the end of mitosis
  – Two daughter cells are formed
  – Identical to the parent cell


• Cell continues through the cell cycle
These photos are of a
dividing plant cell. They
represent the transitions
from…
 A. Interphase to Prophase
 B. Prophase to Metaphase
 C. Metaphase to Anaphase
 D. Anaphase to Telophase
These photos are of a
dividing plant cell. They
represent the transitions
from…
 A. Interphase to Prophase
 B. Prophase to Metaphase
 C. Metaphase to Anaphase
 D. Anaphase to Telophase
What stage is the marked
cell in?




 A. Prophase
 B. Anaphase
 C. Telophase
 D. Metaphase
What stage is the marked
cell in?




 A. Prophase
 B. Anaphase
 C. Telophase
 D. Metaphase
What stage is the marked
cell in?




 A. Prophase
 B. Anaphase
 C. Telophase
 D. Metaphase
What stage is the marked
cell in?




 A. Prophase
 B. Anaphase
 C. Telophase
 D. Metaphase
          What We Learned…
• The four stages of mitosis

• The structure of chromosomes

• The difference in cytokinesis between plant
  and animal cells

				
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posted:12/11/2011
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