Tissues: Beyond Cells

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TissuesBeyond Cells
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• All cells come from previously existing cells.

Mitosis

• One fertilized egg (zygote) undergoes mitosis
  many, many times to produce a baby.
• An adult human contains 75 100 trillion cells.
• 300 different types of cells in the body.

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• How does one fertilized egg develop into all of
  the different types of cells found in a human?

skin cells
fat cells
muscle cells
bone cells
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Answer Cell Specialization

• Specialized cells have physical and chemical
  differences that allow them to perform different
  functions

• Red blood cells carry oxygen in the blood

• Plant leaf cells perform photosynthesis

• Nerve cells transmit electrical impulses

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Genes

• How did one cell give rise to so many different
  types of cells in one organism?

• Genes (base pair sequences) turn on and off to
  control the characteristics and functions of a
  cell.
• Many factors influence what genes are turned on
  and off, including the environment and
  neighbouring cells.

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Stem Cells

• Stem cells are undifferentiated cells that can
  divide to form specialized cells.

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Levels of Organization

• Cells in organisms are organized into tissues.
• Tissues are collections of similar cells that
  perform a particular function.
• Tissues are organized into organs.
• Organs are organized into organ systems.

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• More than one kind of cell or tissue are found in
  any organ.

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• Different cells, tissues, organs and organ
  systems are found in animals and plants.