The Cell Cycle: Interphase, Mitosis and Cytokinesis

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The Cell CycleInterphase, Mitosis and
Cytokinesis

• Gridlock Rules

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Introduction You should be able to

• Define interphase, mitosis and cytokinesis
• Describe the cell cycle
• Discuss the events and significance of mitosis.

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Definitions

• Interphase the period during the cell cycle
  between cell divisions, during which DNA
  replication and protein synthesis take place.

More...
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Definitions (cont).

• Mitosis is the process by which the nucleus of
  a cell is divided into two nuclei, each with the
  same number and kinds of chromosomes as the
  parent cell.
• Cytokinesis is the process by which the
  cytoplasm divides forming two distinct cells.

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Review

• Chromosomes are structures in the cell that
  contain genetic information that is passed from
  one generation to the next.

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Chromosomes

• Only visible during mitosis
• Made up of chromatin (DNA and proteins)
• Cells of every organism have a specific number of
  chromosomes. (Goldfish94, Humans46)

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Chromosome Structure

• Each chromosome is made up of two identical
  chromatids joined at a specific site called the
  centromere.

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The Cell Cycle
Interphase
Mitosis

• Cytokinesis

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Interphase

• Period in between cell divisions
• Usually longer than other phases
• Chromosomes are unraveled, the DNA is at work
• 3 main parts of interphase
• G1 , S , G2

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Interphase (cont.)

• G1- Cell growth and development
• S- DNA replication Protein Synthesis
• G2- Organelle replication

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Interphase
Animal Plant
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Mitosis

• Prophase
• Metaphase
• Anaphase
• Telophase

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Prophase

• Longest phase of mitosis
• Chromosomes begin to form visible coils
• Centrioles move to opposite ends of the cell (no
  centrioles in plant cells)
• Spindle fibers form
• Nucleolus disappears
• Nuclear envelope breaks down

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Prophase
Animal Plant
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Metaphase

• Shortest phase of mitosis
• Chromosomes are fully coiled
• Chromosomes line up at the middle of the cell
• Spindle fibers form star-like patterns around the
  centrioles called asters

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Metaphase
Animal Plant
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Anaphase

• Begins when the sister chromatids begin to
  separate
• Chromatids move to opposite ends of the cell
• Anaphase ends when the chromatids stop moving

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Anaphase
Animal Plant
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Telophase

• Chromatids uncoil
• Two nuclear envelopes form
• Spindle fibers disappear
• Nucleoli become visible
• Telophase is the end of mitosis, but not the end
  of cell division.

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Telophase
Animal Plant
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Animal Cell Mitosis
I
M
P
T
A
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Plant Cell Mitosis
I
M
P
T
A
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Cytokinesis

• Immediately following mitosis
• Cytoplasm divides
• Two separate cells are formed

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Cytokinesis
Animal
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Cell Cycle Summary

• Interphase
• Mitosis
• Prophase
• Metaphase
• Anaphase
• Telophase
• Cytokinesis

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Plant Vs. Animal Cellular Division

• Animal Cells have centrioles, Plant cells do not

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Plant Vs. Animal Cellular Division

• Animal cells form a cleavage furrow during
  cytokinesis (cell membrane pinches in the middle)

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Plant Vs. Animal Cellular Division

• Plants generate a cell plate at the equator
  during anaphase.
• Cell plate is filled with cellulose to make a new
  cell wall.

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Animal Cell
Plant Cell
Cleavage Furrow
Cell Plate
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Prokaryote Vs. Eukaryote Cell Division

• Prokaryotes divide by process called Binary
  Fission
• They only have one chromosome called a nucleoid
• Nucleoid is copied and separated during division

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Prokaryote Vs. Eukaryote Cell Division

• Binary fission produces 2 identical daughter
  cells
• Can happen as fast as every 20 minutes.

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Nucleoid
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Prokaryote Vs. Eukaryote Cell Division

• Eukaryotes produces 2 or more chromosomes
• Organelles must be evenly separated into the new
  cells
• Slower process (Human cells take over 16 hours to
  divide)

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Cancer

• Cancer is the uncontrolled growth and division of
  cells
• group of cancer cells is a tumor
• As the tumor grows, it destroys neighboring cells
  and tissues

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Cancer

• Two types of tumors
• . Benign- cells grow in a ball, does not invade
  other cells.
• . Malignant- unorganized growth that can spread
  to other parts of the body or tissues.

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Cancer Cells