Mitosis and Meiosis Lesson 3.2 : Cell Division is part of the cell cycle Lesson 4.3: Meiosis is a special form of cell division

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Mitosis and Meiosis Lesson 3.2 Cell Division
is part of the cell cycleLesson 4.3 Meiosis is
a special form of cell division
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3.2 The cell cycle includes interphase and cell
division

• All living things live, grow, reproduce, and die
  in a process called a life cycle.
• Cell Cycle the normal sequence of development
  and division of a cell.
• Cell cycle consists of two main phases
  interphase mitosis/cytokinesis

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Interphase

• Part of the cell cycle during which a cell is not
  dividing.
• The cell grows to about twice the size it was
  when first produced.
• The cell engages in normal activities
  transporting materials in and transporting wastes
  out cellular respiration occurs providing energy
  to the cell
• It duplicates its DNA exactly

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Cell Division Phase

• Mitosis part of the cell cycle during which the
  nucleus divides
• Cytokinesis the divison of the parent cells
  cytoplasm occurs immediately after mitosis
• Results the original (parent cell) cell splits
  into two genetically identical daughter cells

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Mitosis Steps

1. Prophase Nuclear membrane disappears
   Chromosomes form
2. Metaphase Chromosomes line up in the middle of
   the cell
3. Anaphase Chromosome pairs split resulting in two
   separate identical chromosomes
4. Telophase/Cytokinesis nuclear membrane forms
   around each group of chromosomes Cytoplasm
   divides to form two identical cells

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• Nuclear membrane disappear Chromosomes form
• Chromosomes line up in the middle of the cell
• Chromatids split resulting in two separate
  identical chromosomes
• nuclear membrane forms around each group of
  chromosomes Cytoplasm divides to form two
  identical cells

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4.3 Meiosis is necessary for sexual reproduction
Making a new ME

• Diploid cell any cell that contains the full
  number of chromosomes (human body cells)
• Gametes cells that contain half of the usual
  number of chromosomes (one chromosome from each
  pair) haploid cells (egg cell sperm cell)
• Fertilization process that takes place when a
  sperm and egg cell combine to form one new cell
• Meiosis a special kind of cell division that
  produces haploid cells
• Meiosis only takes place in the reproductive
  tissues of an organism

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Meiosis I

• Before it begins, the chromosomes of the parent
  cell are copied (twice as many chromosomes as
  usual
• Prophase 1 Duplicated chromosomes pair up and
  nuclear membrane disappears
• Metaphase 1 Chromosome pairs line up in the
  center of the cell
• Anaphase 1 Two copies of one homolog are pulled
  apart
• Telophase 1 Cytokinesis a new cell membrane
  forms at the center of the cell and the cytoplasm
  is separated to form 2 daughter cells.

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Meiosis II

• Prophase 2 There is one copy of each chromosome
  (two chromatids) attached together
• Metaphase 2 Each chromosome lines up along each
  cells center
• Anaphase 2 Each chromosome separates (into two
  identical chromatids) and are pulled to opposite
  poles on each cell
• Telophase 2 and Cytokinesis A new cell membrane
  forms splitting the cytoplasm to form four
  haploid cells
• In male organisms, these gametes become sperm
• In female organisms, at least one of the cells
  becomes an egg. The rest dissolve back into the
  organism.

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Meiosis and Mitosis differ in some important ways

• Meiosis
• Haploid Cells (gametes)
• Two cell divisions
• Chromosomes are copied before the first cell
  division but not the second
• Daughter cells produced contain only half the
  genetic material of the parent

• Mitosis
• Diploid Cells (human body cells)
• One cell division
• Chromosomes are always copied before division
• Daughter cells produced contain exactly the same
  genetic material as the parent

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