B2.1 Membrane Transport

Question 1

what is an essential feature of the Davson-Danielli model of membrane structure?

Answer 1

a layer of lipid sandwiched between 2 layers of protein

Question 2

what is facilitated diffusion?

Answer 2

needs a channel protein in the cell membrane to transport polar, charged and water soluble molecules across the membrane

Question 3

what happens in endocytosis?

Answer 3

particles are enclosed in vesicles made from the cell surface membrane and transported into the cell

Question 4

what happens in exocytosis?

Answer 4

vesicles containing large particles are fused with the cell surface membrane and released from the cell

Question 5

what are the 6 main functions that membrane proteins can carry out? CCCHIP

Answer 5

cell to cell adhesion, cell to cell communication, channels for passive transport, hormone binding sites, immobilised enzymes, pumps for active transport