Membrane Transport Proteins Doorways to the cell

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Membrane Transport ProteinsDoorways to the cell

• Jeanne Beck

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Organic Review

• Positive and negative charges in atoms and
  electronegativity
• Conformational changes due to thermodynamics
• Changes in d-negative charges due to bonding
• Precise fit of incoming molecule induces further
  conformational changes.
• All of these steps are required for transport
  into the cell.

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Types of Membrane Proteins

• Diffusion
• Ion Channels
• ATP-Pumps
• Transporters

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ATP-Powered Pumps

• ATP Pumps are enzymes termed ATPases.
• Active transport system
• Four types of ATP-Pumps
• P-Type
• F-Type
• V-Type
• ABC Class
• Examples low CA and high NA, low pH in
  lysosomes, vacuoles, and in the stomach lumen.

Figure 15-3
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15.5 Properties of ATP-powered pumps
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15.5 Properties of ATP-powered pumps
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Ion Channels

• Transports large amounts of water and small ions
  into the cell down the gradient.
• This method is rapid, about 108 per second.
• Usually always open or always closed.
• Chapter 21 covers this method in detail, so Ill
  leave that discussion for the lucky student to
  come.

Figure 15-3
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Transporters

• Transports a wide variety of ions and molecules
• One or a few at a time
• Requires a conformational change
• Slow
• Three types of Transporters
• Uniporters
• Antiporters
• Symporters

Figure 15-3
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Transporter Classes
Figure 15-3

• Uniporters move molecules down a gradient into or
  out of the cell.
• Active transporters
• Antiporters move a molecule up a gradient coupled
  with a molecule that transports down a gradient
  at the same time.
• Symporters move a molecule up a gradient but it
  must be coupled with another molecule also up a
  gradient at the same time.

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Summary
Figure 15-3