4. Exchange Across Cell Membranes: Active Transport

Question 1

is active transport a passive or active process?

Answer 1

active

Question 2

define active transport

Answer 2

active transport transports molecules and ions across membranes, usually against a concentration gradient

Question 3

what are co-transporters?

Answer 3

a type of carrier protein

Question 4

what do co-transporters allow?

Answer 4

they use the concentration gradient of one molecule to move the other molecule against its own concentration

Question 5

what other protein is involved in active transport?

Answer 5

carrier proteins, ATP is needed to complete this

Question 6

what affects the rate of active transport?

Answer 6

1. the speed of individual carrier proteins, the faster they work, the faster the rate of active transport
2. number of carrier proteins present, the more carrier proteins, the faster the active transport
3. the rate of respiration, if respiration is inhibited, active transport cant take place
4. the availability of ATP

Question 7

glucose is absorbed in the Mammalian Ileum, by which process?

Answer 7

co-transport

Question 8

describe the process of co-transport for glucose

Answer 8

1. sodium ions are actively transported out of the ileum epithelial cells, via a sodium-potassium concentration gradient, as there is now a low sodium concentration in the cell and a high one outside of the cell
2. this causes sodium ions from outside the cell (lumen) to diffuse into the epithelial cell via sodium-glucose co-transport proteins
3. the co-transporter carries glucose and amino acids as well as sodium into the cell, resulting in glucose concertation within the cell to increase
4. glucose diffuses out of the cell into the blood, through a protein channel, via facilitated diffusion down its concentration gradient.