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TRANSPORT ACROSS MEMBRANES

TRANSPORT ACROSS MEMBRANES. THE WAY CELLS REGULATE THEIR CONTENTS. TWO MAJOR TYPES OF TRANSPORT. PASSIVE: Only from high concentration to low ACTIVE: Can actually pump up a gradient using energy from some other source such as ATP (Primary) or another gradient (Secondary). Passive Transport.

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TRANSPORT ACROSS MEMBRANES

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  1. TRANSPORT ACROSS MEMBRANES THE WAY CELLS REGULATE THEIR CONTENTS

  2. TWO MAJOR TYPES OF TRANSPORT • PASSIVE: Only from high concentration to low • ACTIVE: Can actually pump up a gradient using energy from some other source such as ATP (Primary) or another gradient (Secondary)

  3. Passive Transport • Diffusion • Bulk Flow • Electrodiffusion • Current Flow • Osmosis • Facilitated Diffusion

  4. Diffusion Before: • Diffusion occurs when concentration in one region is greater than in another • The end result is an even distribution called equilibrium After:

  5. Diffusion across a permeable membrane Before: • Diffusion occurs when concentration in one region is greater than in another • The end result is an even distribution called equilibrium After:

  6. Impermeable membrane Before: • Diffusion can not occur After:

  7. Bulk Flow • Analogous to the flow of water through a pipe • Through pores in membranes • Through blood vessels • Through other tubular structures

  8. - Current Flow POSITIVE REGION NEGATIVE REGION + CATIONS AND ANIONS MOVE IN OPPOSITE DIRECTIONS CARRYING ELECTRICAL CURRENT CURRENT = FLOW OF CATIONS - FLOW OF ANIONS

  9. SOLUTE NO SOLUTE Osmosis Water moves across a semi-permeable membrane to the side where the solute is most concentrated After: Before: SOLUTE NO SOLUTE

  10. Facilitated Diffusion • 1. Molecule binds to carrier • 2. Carrier changes conformation • 3. Molecule released on other side • 4. Purely passive process- stops when concentrations are equal

  11. ACTIVE TRANSPORT REQUIRES AN INPUT OF ENERGY • USUALLY IN THE FORM OF ATP • ATPase IS INVOLVED • SOME ASYMMETRY IS NECESSARY • CAN PUMP UPHILL

  12. ACTIVE TRANSPORT ADP ATP

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