KA3b - Ion transport pumps and generation of ion gradients

What is the concentration gradient?

Difference in concentration of a solute across the plasma membrane

What is the electrical potential difference?

It's created when there is a difference in electrical charge on the two sides of the membrane

How is the electrochemical gradient formed?

When a solute carries a net charge - the concentration gradient and electrical potential difference combine, which forms the electrochemical gradient

What does the electrochemical gradient do?

Determines the transport of the solute

Why do ion pumps; such as sodium potassium pump use energy from the hydrolysis of ATP?

To establish and maintain ion gradients

How does the sodium potassium pump work?

Pumps sodium ions and potassium ions against steep concentration gradients by using energy directly from ATP hydrolysis

What occurs within step 1 of the sodium potassium pump?

The pump has high affinity for sodium ions inside the cell; three sodium ions bind

What happens in step 2 of the sodium potassium pump?

The pump has been phosphorylated by ATP

When does a conformational change occur within the sodium potassium pump?

After phosphorylation it causes a change within the protein

What happens after the conformational change within the sodium potassium pump?

It has low affinity for sodium ions and they're released out of the cell

What does the sodium potassium pump have high affinity for after the conformational change?

High affinity for potassium ions outside of the cell

How many potassium ions can bind to the sodium potassium pump?

2 potassium ions bind

What happens after the potassium ions have bound to the sodium potassium pump?

The pump is then dephosphorylated

What phrase is used to remember how many potassium ions bind within the sodium potassium pump?

Toucan (two potassium ions enter)

What is the process called that causes another conformational change to occur within the protein?

Dephosphorylation

Does dephosphorylation cause the pump to have high affinity for potassium ions; true or false?

False

What happens to the sodium potassium pump after dephosphorylation causes a conformational change?

Pump has low affinity for potassium ions and are released into the cell

How many sodium ions and potassium ions are transported for each ATP hydrolysed; and which direction are they transported?

Three sodium ions transported outside the cell; two potassium ions transported into the cell

What does the sodium potassium pump establish?

Both concentration gradients and an electrical gradient

Sodium potassium pump is found in most animal cells; but what does it account for?

High proportion of the basal metabolic rate within many organisms

Give 3 examples of the basal metabolic rate in organisms

Maintaining osmotic balance in animal cells, generation of ion gradient for glucose symport in small intestine & generation and long-term maintenance of ion gradient for resting potential in neurons

What does the sodium potassium pump generate within the epithelial cells of the small intestine?

A sodium ion gradient across the plasma membrane

What does this sodium ion gradient do?

Drives the active transport of glucose through a glucose transporter pump

What happens within the glucose transporter?

Sodium ions enter down their concentration gradient whilst the transporter simultaneously pumps glucose into the cell against its concentration gradient

What is the function of a symporter?

It pumps transport molecules across the plasma membrane simultaneously and in the same direction