Co - transport

Question 1

How do microvilli increase the rate of movement across membranes?

Answer 1

Epithelial cells lining the ileum possess microvilli which provided more surface area for the insertion of carrier proteins through which diffusion, facilitated diffusions and active transport can take place

Question 2

What are microvilli?

Answer 2

Microvilli are finger like projections

Question 3

How does the number of protein channels and carrier proteins increase the rate of movement across membranes?

Answer 3

By increasing the number of protein channel and carrier proteins in any given area of the membrane, the rate of movement across the membrane increases

Question 4

What is co transport?

Answer 4

Co transport is the combined movement of substances across a cell membrane through a carrier protein

Question 5

What are the two other types of movement that are involved in co transport?

Answer 5

Co transport involves a combination of facilitated diffusion and active transport

Question 6

What are the conditions that will enable glucose to be absorbed from the lumen?

Answer 6

To absorb glucose from the lumen to the gut there must be a higher concentration of glucose in the lumen compared to the epithelial cell

Question 6

Why is active transport and facilitated diffusion involved in co transport?

Answer 6

Usually there is more glucose in the epithelial cells compared to the lumen, so active transport and facilitated diffusion is required

Question 7

Outline the process of co transport of glucose and sodium ions into the ileum: (5pts)

Answer 7

1) Sodium ions are actively transported out of the epithelial cell into the blood

2) This reduces the sodium ion concentration in the epithelial cell

3) Sodium ions can then diffuse from the lumen down their concentration gradient into the epithelial cell

4) The protein the sodium ions diffuse through is a cotransporter protein, so either glucose or amino acids also attach and are transport together into the epithelial cells against their concentration gradient

5) Glucose then moves by facilitated diffusion from the epithelial cells to the blood, down a concentration gradient

Question 8

Why is the concentration of glucose in the blood lower than in the epithelial cells?

Answer 8

The concentration of glucose in the blood is lower than in the epithelial cells because within the capillary the blood flows consistently and carries away absorbed glucose