Topic 2- Active Transport Flashcards
How do substances move
Against a concentration gradient
Does active transport require energy?
Yes
How does a carrier protein work?
-A molecule attaches to the carrier protein
-The protein changes shape
-This moves the molecule across the membrane
-Releases it onto the other side
What are the two main differences between facilitated and active transport?
-Active transport usually moves solutes from a low to a high concentration however in facilitated diffusion they always move from a high to a low concentration
-Active transport requires energy-facilitated diffusion and does not
What role does ATP play in active transport?
-Undergoes a hydrolysis reaction, splitting up into ADP and Pi
-This releases energy so that the solutes can be transported
What is a co-transporter?
A type of carrier protein
What is the function of a co-transporter?
They bind two molecules at a time
How does a co-transporter work?
The concentration gradient of one of the molecules is used to move the other molecule against it’s concentration gradient
Explain the cotransport and absorption of glucose (Step 1)
-Glucose is absorbed into the bloodstream in the small intestine
-In the mammaligh Liem( final part of a mammal’s small intestine) the concentration of glucose is too low for glucose to diffuse out onto the blood
-So glucose is absorbed from the lumen (middle) of the ileum by co-transport
Explain the cotransport and absorption of glucose (Step 2)
-Sodium ions are actively transported out of the epithelial cells in the ileum into the blood by a sodium-potassium pump
-This creates a concentration gradient
-There is now a higher concentration of sodium ions
in the lumen of the ileum than inside the cell
Explain the cotransport and absorption of glucose (Step 3)
-This causes the sodium ions to diffuse from the lumen of the ileum into the epithelial cell, down their concentration gradient
-They do this via the sodium-glucose co-transporter proteins
-The cotransporter carries glucose into the cell with the sodium
-As a result, the concentration of glucose inside the cell increases
-The cotransporter carries glucose into the cell with the sodium
-As a result, the concentration of glucose in the cell increases
Explain the cotransport and absorption of glucose (Step 4)
-Glucose diffuses out of the cell, into the blood, and down its concentration through a protein channel by facilitated diffusion
What are the factors that affect the rate of diffusion?
-The speed of the individual carrier proteins- the faster they work, the faster the rate of active transport
-The number of carrier proteins present- the more proteins the faster the rate
-The rate of respiration in the cell and the availability of ATP- if respiration is inhibited, active transport can’t take place
Give some examples of active transport
-Uptake of glucose and amino acids in the small intestine
-Absorption of mineral ions by plant roots
-Excretion of hydrogen ions and urea by kidneys
-Exchange of sodium and potassium ions in neurons and muscle cells
