Transport across cell membranes Flashcards

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1
Q

Simple vs Facilitated Diffusion?

A

Simple = molecules move directly through the phospholipid bilayer

Facilitated = molecules pass through transport proteins (large use carrier, charged use channel)

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2
Q

Factors that affect rate of diffusion?

A

surface area (increase = increase rate of diffusion)

concentration gradient (increase = increase rate of diffusion)

thickness (decrease = decrease diffusion distance = increase rate of diffusion)

temperature (increase = increase kinetic energy = molecules move faster = increase rate of diffusion)

size of molecules (smaller molecules = increase rate of diffusion)

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3
Q

What is Ficks Law?

A

(Surface Area x Concentration Gradient)/Thickness

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4
Q

Define Osmosis?

A

movement of water molecules from an area of high water potential to an area of low water potential through a partially permeable membrane

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5
Q

Which liquid has the highest water potential?

A

distilled/pure water

has a value of 0kPa

lower water potential by adding solutes (makes water potential negative)

water moves from less negative water potential (e.g. -35 kPa) to more negative water potential (e.g. -75 kPa)

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6
Q

Surround animal cell with pure water?

A

swells and burst (water enters by osmosis)

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7
Q

Surround plant cell with pure water?

A

swells but does not burst

cell wall prevents it from bursting

made of cellulose – strong material

the cell is Turgid

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8
Q

Surround animal cell with concentrated sugar/salt solution?

A

shrinks (water leaves by osmosis)

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9
Q

Surround plant cell with concentrated sugar/salt solution?

A

water leaves by osmosis

cell wall prevents cell from shrinking, keeps it rigid

the protoplast (cell membrane plus contents) shrink

the cell is Plasmolysed

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10
Q

Define Active Transport?

A

movement of molecules from an area of low concentration to an area of high concentration using ATP and carrier proteins (against concentration gradient)

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11
Q

Describe the process of active transport?

A

molecules (in area of low concentration) bind to carrier protein

ATP breaksdown to ADP, Pi and Energy

the Pi and Energy cause the carrier protein to change shape

carrier protein releases molecules on opposite side (in area of high concentration)

the carrier protein releases the attached Pi to return to its original shape

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12
Q

Absorption of Glucose and Amino Acids in SI via cotransport?

A

sodium ions are actively transported from the cells lining the SI into the blood

lowers the sodium ion concentration in the cell

therefore sodium ions move from the lumen of the SI into the cell

this pulls in glucose and amino acids via a cotransport protein

therefore glucose and amino acids builds up in the cell and moves into the blood by diffusion

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