A Tour of the Cell

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TEM - interior
SEM - surface
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Animal Cell
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Plant Cell
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Endomembrane System
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Endoplasmic Reticulum

• Often referred to as ER.
• Makes up to 1/2 of the total membrane in cells.
• Often continuous with the nuclear membrane.

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Structure of ER

• Folded sheets or tubes of membranes.
• Very fluid in structure with the membranes
  constantly changing size and shape.

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Types of ER

• Smooth ER no ribosomes.
• Used for lipid synthesis, carbohydrate storage,
  detoxification of poisons.
• Rough ER with ribosomes.
• Makes secretory proteins.

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Function of Golgi Bodies

• Processing - modification of ER products.
• Distribution - packaging of ER products for
  transport.

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Golgi Vesicles

• Small sacs of membranes that bud off the Golgi
  Body.
• Transportation vehicle for the modified ER
  products.

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Lysosome Function

• Breakdown and degradation of cellular materials.
• Contains enzymes for fats, proteins,
  polysaccharides, and nucleic acids.
• Over 40 types known.

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Lysosomes

• Important in cell death.
• Missing enzymes may cause various genetic enzyme
  diseases.
• Examples Tay-Sachs, Pompes Disease

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Vacuoles

• Structure - single membrane, usually larger than
  the Golgi vesicles.
• Function - depends on the organism.

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Function

• Water regulation.
• Storage of ions.
• Storage of hydrophilic pigments.
  (e.g. red and blues in flower petals).

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Function Plant vacuole

• Used to enlarge cells and create turgor pressure.
• Enzymes (various types).
• Store toxins.
• Coloration.

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Enzymes in a crystal
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Mitochondria

• Structure 2 membranes. The inner membrane has
  more surface area than the outer membrane.
• Matrix inner space.
• Intermembrane space area between the membranes.

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Inner Membrane

• Folded into cristae.
• Amount of folding depends on the level of cell
  activity.
• Contains many enzymes.
• ATP generated here.

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Function

• Cell Respiration - the release of energy from
  food.
• Major location of ATP generation.
• Powerhouse of the cell.

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Chloroplasts

• Structure - two outer membranes.
• Complex internal membrane.
• Fluid-like stroma is around the internal
  membranes.

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Inner or Thylakoid Membranes

• Arranged into flattened sacs called thylakoids.
• Some regions stacked into layers called grana.
• Contain the green pigment chlorophyll.

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Function

• Photosynthesis - the use of light energy to make
  food.

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Plastids

• Group of plant organelles.
• Structure - single membrane.
• Function - store various materials.

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Examples

• Amyloplasts/ Leucoplasts - store starch.
• Chromoplasts - store hydrophobic plant pigments
  such as carotene.

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Cytoskeleton

• Network of rods and filaments in the cytoplasm.

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Functions

• Cell structure and shape.
• Cell movement.
• Cell division - helps build cell walls and move
  the chromosomes apart.

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Cytoskeleton

• Very dynamic changing in composition and shape
  frequently.
• Cell is not just a "bag" of cytoplasm within a
  cell membrane.

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Cell Wall

• Nonliving jacket that surrounds some cells.
• Found in
• Plants
• Prokaryotes
• Fungi
• Some Protists

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Plant Cell Walls

• All plant cells have a Primary Cell Wall.
• Some cells will develop a Secondary Cell Wall.

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Cell Walls

• May be made of other types of polysaccharides
  and/or silica.
• Function as the cell's exoskeleton for support
  and protection.

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