Transport across cell membranes Flashcards

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1
Q

What is diffusion?

A

The net movement of particles from an area of higher concentration to an area of low concentration
- Diffusion is a passive process

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2
Q

What is meant by facilitated diffusion?

A

Large or charged particles diffuse through carrier proteins or channel proteins - speeding up the process
- Higher to a lower concentration gradient and a passive process

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3
Q

How do carrier proteins enable large molecules to move across the membrane?

A
  • Large molecule attaches to a carrier protein in the membrane
  • Protein changes shape
  • Releases the molecule on the opposite side of the membrane
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4
Q

How do channel proteins enable large molecules to move across the membrane?

A
  • Channel proteins form pores in the membrane for charged particles to diffuse through
  • Different channels (sodium channel) facilitate the diffusion of different charged particles
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5
Q

What 3 factors affect the rate of simple diffusion?

A
  • The concentration gradient, higher it is the faster the rate of diffusion
  • The thickness of the exchange surface, thinner the exchange surface the shorter the diffusion distance
  • The surface area, larger the surface area the faster the rate of diffusion
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6
Q

What 2 factors affect the rate of facilitated diffusion?

A
  • Concentration gradient, higher the concentration gradient faster the rate of facilitated diffusion
  • Number of channel/carrier proteins, faster the rate of facilitated diffusion
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7
Q

What is osmosis?

A

Diffusion of water molecules across a partially permeable membrane from an area of higher water potential to an area of lower water potential

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8
Q

What 3 factors affect the rate of osmosis?

A
  • The water potential gradient, higher water potential gradient faster the rate of osmosis
  • Thickness of the exchange surface, thinner surface faster rate of osmosis
  • Surface area, larger surface area faster rate of osmosis
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9
Q

What is active transport?

A

Moves solutes from a low to a high concentration, requiring ATP

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10
Q

What is meant by co-transporters?

A

A type of carrier protein

  • Bind two molecules at a time
  • Concentration gradient of one molecules is used yo move the other molecule against its own concentration gradient
  • E.g. sodium ions and glucose
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11
Q

What 3 factors affect the rate of active transport?

A
  • Speed of individual carrier proteins
  • Number of carrier proteins present
  • The rate of respiration/availability of ATP
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