Cell Division

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Cell Division

• Mitosis

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Cell Division Vocabulary

• Mitosis- is the process in which the nucleus
  divides to form two identical nuclei.
• Chromosome- is a structure in the nucleus that
  contains hereditary material.
• Asexual Reproduction- a new organism is produced
  from ONE organism.

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The Cell Cycle

• The regular sequence of growth and division that
  cells undergo is known as the cell cycle.
• Steps
• Cells grow function, DNA copied, Cell grows and
  prepares for mitosis, Mitosis happens, and
  Cytoplasm divides.

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The Phases

1. Interphase
2. Prophase
3. Metaphase
4. Anaphase
5. Telophase
6. Cytokinesis

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Interphase

• During interphase, the cell grows to its mature
  size, makes a copy of its DNA, and prepares to
  divide into two cells.
• DNA is Replicated
• (copied)

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Next Stage is Mitosis 4 Parts

• Prophase
• Metaphase
• Anaphase
• Telophase

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Prophase

• Threadlike chromatin in the cells nucleus begins
  to condense and coil.

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Chromatin Condenses to Form Chromosomes
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The Chromosome

• Chromosome X shaped cell structure that
  directs cell activities and passes on traits to
  new cells.
• Each identical strand of the chromosome is called
  a chromatid.
• The strands are held together by a structure
  called the centromere.
• Chromatin Loosely coiled DNA

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Metaphase Meet in the Middle

• Chromosomes line up at the center of the cell.
• Each chromosome attaches to a spindle fiber at
  its centromere.

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METAPHASE!!!!!!
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Anaphase Split Apart

• Chromosomes are pulled apart by the spindle
  fibers and brought to each end of the cell.

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Telophase Two New Nuclei

• Two new nuclei are formed
• Chromosomes begin to uncoil

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Cytokinesis

• Animal Cells Cell membrane pinches in between
  the two new cells.
• Plant Cells Cell plate forms between the two
  cells. Cell Wall is too rigid to be pinched
  apart.

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Homework

• Illustrate the Six stages of the Cell Cycle. How
  you illustrate them or what materials you use is
  completely up to you. Just be sure that each
  stage is clearly illustrated and labeled.

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Length of the Cell Cycle of a Human Liver Cell

• Interphase 21 hours
• Growth 9 hours
• DNA Replication 10 hours
• Preparation for Division 2 hours
• Mitosis 1 hour
• Prophase
• Metaphase
• Anaphase
• Telophase

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Sea Urchin Cell Cycle

• Sea Urchin Cell Cycle takes 2 hours

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Human Brain Cells

• Never divide, they remain in the first part of
  interphase for as long as they live!

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Review
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Cellular Asexual Reproduction

• Requires one organism to reproduce
• Hereditary material will be IDENTICAL to the
  parent.
• Recall Mitosis is the division of the nucleus.
  Question What if an organism doesnt have a
  nucleus?
• Fission- an organism copies its genetic material
  then divides into 2 identical organisms

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Fission
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Budding and regeneration

• Budding- type of asexual reproduction made
  possible because of cell division.
• The bud on the adult organism becomes large
  enough it breaks away to live on its own.
• Regeneration- the process that uses cell division
  to re-grow body parts.
• Example Starfish

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Budding
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The Steps of the Ladder

• Each rung of the DNA ladder is made up of a pair
  of molecules called nitrogen bases.
• There are four kinds of Nitrogen Bases
• Adenine (A)
• Thymine (T)
• Guanine (G)
• Cytosine (C)

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The Pairs

• Adenine only pairs with Thymine
• Guanine only pairs with Cytosine

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DNA Replication

• The ladder unzips and the rungs find new pairs
  that are floating in the nucleus.