Week 1 Lecture 1 Flashcards

1
Q

What is the cell membrane composed of?

A

A phospholipid bilayer

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2
Q

What substances can diffuse through the cell membrane?

A

Lipid-soluble molecules and gases

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3
Q

What substances cannot cross the cell membrane?

A

Water-soluble molecules and organic anions (proteins)

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4
Q

What does permeability depend on?

A

Molecular size, lipid solubility, and charge

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5
Q

What is membrane permeability?

A

If a substance can cross a membrane, the membrane is permeable to that substance

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6
Q

Can gases diffuse across the membrane?

A

Yes, they can

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7
Q

Can polar molecules and ion diffuse across the membrane?

A

No, they need the help of proteins e.g. channels or transporters to cross

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8
Q

What is simple diffusion

A

small, lipid-soluble molecules and gases pass either directly through the phospholipid bilayer or through pores

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9
Q

Is simple diffusion passive or active transport?

A

Passive, no energy is required, movement is down [] gradient

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10
Q

What is the relative rate of simple diffusion proportional to?

A

The gradient across the membrane, the greater the concentration gradient, the greater the rate of diffusion

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11
Q

What does simple diffusion require?

A

brownian motion

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12
Q

How is facilitated diffusion similar to simple diffusion?

A

Both are passive, involve substance moving down it’s [] gradient

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13
Q

How is facilitated and simple diffusion different?

A

Facilitated diffusion requires carrier proteins while simple diffusion does not (substance passes directly through phospholipid bilayer or pores)

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14
Q

What is facilitated diffusion?

A

process of diffusion in which molecules diffuse across the membrane with the assistance of carrier proteins

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15
Q

What are carrier proteins?

A

aid the movement of polar molecules across the cell membrane

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