CHAPTER 12 PART 2

What are pumps in the context of membrane proteins?

• Devices that increase water pressure

• Proteins that maintain a concentration gradient by moving substances against their concentration gradient

• Channels that allow substances to move along their concentration gradient

• Enzymes that break down substances within the cell

What is required for the functioning of pumps in cell membranes?

• Sunlight

• Cellular energy

• Water

• Oxygen

Which types of pumps are mentioned as being present in neurons?

• Sodium-potassium pumps and calcium pumps

• Hydrogen pumps and bicarbonate pumps

• Glucose pumps and insulin pumps

• Water pumps and urea pumps

What are channels in the membrane designed to do?

• Use ATP to move ions against their concentration gradients

• Allow ions to move down their concentration gradients

• Prevent any ions from moving across the membrane

• Convert ions into energy

Why do channels not require ATP?

• Because they move ions against the concentration gradient

• Because they use light energy to move ions

• Because specific ions diffuse down the concentration gradient

• Because they are permanently closed

Which type of channel is controlled by the binding of a ligand?

• Leak channel

• Voltage-gated channel

• Ligand-gated channel

• ATP-gated channel

What triggers the opening of a voltage-gated channel?

• The binding of a neurotransmitter

• A change in the voltage across the membrane

• The concentration of ions inside the cell

• The use of ATP

What happens to the voltage-gated channel during the resting state?

• The gate opens and ions move through the channel.

• The inactivation gate closes and ions cannot move through the channel.

• The activation gate is closed and ions do not move through the channel.

• The channel allows a short period of time for the channel to reset.

What triggers the opening of the gate in a voltage-gated channel during the activation state?

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What is the role of the inactivation gate in a voltage-gated channel?

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