Transport Across The Membrane

Question 1

What is diffusion?

through the membrane

Answer 1

• passive movement
• of small, non-polar, lipid soluble molecules
• from an area of high concentration to an area of low concentration
• the phospholipid bilayer

Question 2

Describe facilitated diffusion.

through the membrane

Answer 2

• requires a channel protein
• transport polar molecules, charged and water soluble molecules across the membrane

Question 3

What is osmosis?

through the membrane

Answer 3

• diffusion of water molecules
• from an area of high water potential to an area to low water potential
• through a partially permeable membrane.

Question 4

Describe active transport?

through the membrane

Answer 4

• transport all types of molecules
• via carrier proteins
• from an area of low concentration to an area of high concentration
• requires energy in the form of ATP.

Question 5

What is endocytosis?

through the membrane

Answer 5

• transport large particles, enclosed in vesicles
• made from the cell surface membrane
• transported into the cell

Question 6

What is exocytosis?

through the membrane

Answer 6

• transport large particles, enclosed in
  vesicles
• made from the cell surface membrane
• then it fused with the cell surface membrane and released from the cell

Question 7

Explain the process of Co-Transport.

of ions through the membrane

Answer 7

• sodium and potassium ions are pumped out of the epithelial cell by active transport into the blood leaving a lower concentration in the cell
• this causes these ions to move in from the lumen by facilitated diffusion
• which at the same time brings glucose and amino acids into the epithelial cell
• these diffuse from a high concentration in the epithelial cell to a low concentration in the blood

Question 8

What is Co-Transport?

through the membrane

Answer 8

A method of membrane transport where two substances are both transported
across a membrane at the same time either in the same direction or opposite directions.

occurs in the epithelial cells in the ileum

Question 9

What increases the rate of diffusion?

through the membrane

Answer 9

increasing:
1. the surface area
2. the steepness of the concentration gradient
3. the shortness of the diffusion path
4. the temperature

Question 10

What are aquaporins?

through the membrane

Answer 10

integral membrane proteins that serve as channels in the transfer of water, and in some cases, small solutes across the membrane