Think about yesterdays Lego Activity

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Think about yesterdays Lego Activity

• Which part of the building represents the cell?
• The tissue?
• The organ?
• The organ system?
• The organism?

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Reproduction

• How do cells interact with each other to
  reproduce a larger, more complex organism?

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Why do cells reproduce?

• 1. So the organism grows
• 2. To make offspring
• 3. To replace injured/dead cells

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Lets Review

• How do single-cell organisms reproduce?
• Asexual Reproduction
• Binary Fission (most often)
• Budding

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How do multi-cellular organisms reproduce?

• Depends on why the organism is reproducing
• Is it replacing dead or injured cells?
• Is it growing?
• Is it producing a new, separate organism
  (offspring)?

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For growth or to replace eukaryotic cells

• Cells go through an
• Asexual Reproduction process
• called the Cell Cycle.

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Three Stages of the Cell Cycle

• 1. Interphase grows, replicate DNA, and makes
  more organelles
• 2. Mitosis Nucleus divides separates
  chromosomes
• 3. Cytokinesis Cell divides into two
• http//www.cellsalive.com/cell_cycle.htm

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Mitosis

• Consists of 4 stages
• 1. prophase
• 2. metaphase
• 3. anaphase
• 4. telophase
• http//www.biologymad.com/master.html?http//www.b
  iologymad.com/CellDivision/CellDivision.htm

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Result of Asexual Reproduction

• All cells (single-cell or multi-cellular) end up
  with an identical clone.

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What happens when a multicellular organism
reproduces an offspring?

• Cells must go through the process of sexual
  reproduction.

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Sexual Reproduction

• Requires 2 specialized cells (gametes), one from
  each parent to unite.
• The offsprings DNA will be a combination of the
  two parents, therefore different from each.

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• All cells in organisms that reproduce via
  sexual reproduction have 2 sets of DNA (one from
  mom/one from dad).
• These cells are called somatic cells

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Stages of Sexual Reproduction

• 1. Interphase
• 2. Mitosis
• 3. Meiosis
• 4. Cytokinesis
• 5. Syngamy

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Vocabulary Terms

• Chromosome 1 set of DNA coiled into an X
• Chromatid ½ of a chromosome
• Gamete ½ of a chromosome