Mitochondria

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Mitochondria

• Found in all eukaryotic cells.
• Responsible for energy production.

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Chloroplasts

• Found only in eukaryotic cells such as plants and
  algae.
• Site of photosynthesis.

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Cytoskeleton
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Cytoskeleton

• Made of long, thin, protein filaments.
• Three sizes
• Microfilaments
• Intermediate filaments
• Microtubules
• Provides internal cell structure.
• Anchor and connect organelles.
• Move parts and products.

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What is the nature of cell membranes?
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Plasma Membrane

• Fluid mosaics of phospholipids, proteins and
  carbohydrates.

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Plasma Membrane

• Phospholipids provide basic architecture.
• Have hydrophilic tails and hydrophobic heads.

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Plasma Membrane

• Proteins act as channels, recognition molecules,
  carrier proteins, etc.
• Carbohydrates help connect cells and play a role
  in identification.

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Diffusion

• Net movement of molecules from areas of high
  concentration to areas of low concentration.
• No energy required.

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Diffusion
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Osmosis

• Type of diffusion.
• Movement of water across semipermeable membrane
  from area of high water concentration to area of
  low water concentration.

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Effect of osmosis on cells in various solutions

• Hypotonic solutions
• High concentration of water in extracellular
  fluid compared to inside the cells causes net
  movement of water into the cell.
• Results in increased cell size.
• Can cause cell to burst.

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Effect of osmosis on cells in various solutions

• Isotonic solutions
• Concentrations of water inside and outside of the
  cell are equal.
• Results in no net movement of water.
• Cell size remains the same.

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Effect of osmosis on cells in various solutions

• Hypertonic solutions
• Concentration of water in cell exceeds that
  outside of cell.
• Results in net movement of water out of the cell.
• Cell shrinks.

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Membrane transport

• Large or hydrophilic substance cannot pass freely
  through the membrane.
• To move them through the membrane, must have
  channel proteins or carrier proteins.

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Passive Transport Ion Channels

• Ions are hydrophilic and the channel must be open
  for the ion to pass through the channel.
• Selective for each ion.
• Ion moves down concentration gradient.

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Passive Transport Facilitated diffusion

• Molecule enters protein carrier.
• Induces protein shape change allowing molecule to
  exit the carrier.

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Passive Transport Facilitated diffusion

• Selective for each molecule.
• Molecule moves down concentration gradient.

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Passive Transport Facilitated diffusion
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Active Transport

• Uses carrier protein.
• Moves molecules against their concentration
  gradient.
• Requires ATP as an energy source.

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Active Transport
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Active Transport
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Endocytosis

• Cells absorb outside material by inverting plasma
  membrane to form a vesicle that encases the
  material.

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Exocytosis

• Moving molecules, particles, and other substances
  contained in vesicles across the plasma membrane
  and out of the cell.