2.1 The Structure

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2.1The Structure Functions of Eukaryotic
Cells
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Endoplasmic Reticulum

• Moves substances between the cytoplasm and
  nucleus in a network of inter-connected, complex
  system of channels sacs (lumen)
• Ribosomes (RNA proteins) synthesize protein and
  are either free-floating in the cytosol (proteins
  for use in cell) or attached to some ER (proteins
  excreted)
• Two types of ER
• Rough endoplasmic reticulum or RER
• (ribosomes attached to the surface)
• Smooth endoplasmic reticulum or SER
• (no ribosomes attached to the surface)

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Rough Endoplasmic Reticulum

• Ribosomes attached to surface
• Manufactures proteins for use in membrane or for
  excretion from the cell. Sends them in vesicles
  to the Golgi Apparatus.
• Ribosomes, while still making proteins, differ in
  structure mechanisms between eukaryotes and
  prokaryotes.

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RER Micrograph
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Smooth Endoplasmic Reticulum

• No attached ribosomes on the surface
• Has enzymes that help build molecules of lipids
  (ie steroids phospholipids) for use in the
  membrane. Sends them in vesicles to the Golgi
  Apparatus.
• SER also detoxifies drugs alcohol and produces
  hormones (ie sex hormones)

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SER Micrograph
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Endomembrane System

• Includes nuclear envelope, ER and the Golgi
  Apparatus.
• It synthesizes, modifies and transports cell
  products (ie protein)
• The organelles are connected to each other by
  transport vesicles (membrane closed sacs for
  transport and storage)

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Golgi Apparatus

• Moves substances from vesicles of the ER through
  a network of complex system of channels sacs
• Stores or modifies proteins (CHO chains) from
  vesicles
• Involved in synthesis of
• plant cell wall
• Produces
• lysosomes
• Transports vesicles
• to cell membrane for
• excretion

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Golgi Apparatus Function

• 1. Molecules arrive in vesicles from ER
• 2. Vesicles fuse with Golgi membrane
• 3. Molecules may be modified by Golgi
• 4. Molecules pinched-off in separate vesicle
• 5. Vesicle leaves Golgi apparatus
• 6. Vesicles may combine with plasma membrane to
  secrete contents

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Golgi Apparatus Micrograph
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Lysosomes Peroxisomes

• Contains digestive enzymes to breakdown
  macromolecules.
• Lysosomes from GA and peroxisomes from ER
• Peroxisome functions
• catalyzing redox reactions
• Breaks down toxic molecules
• Contains catalase
• Lysosome functions
• Catalyze hydrolysis reactions
• Breaks down old cell parts
• Digests invaders

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Vacuoles Vesicles

• Membrane bound storage sacs (vesicles vacuoles)
  or transport sacs (vesicles only)
• Larger vacuoles (ie central) found only in
  plants
• Vesicles smaller more common in animals
• Contents
• Water
• Food
• Ions
• Wastes
• Macromolecules

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Food Vacuole Micrograph
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End Part 2