Transport across cell membranes

• Name and describe five ways substances can move across the cell-surface membrane into a cell

  Simple diffusion of non-polar molecules down a concentration gradient. Facilitated diffusion down a concentration gradient via a protein carrier or channel. Osmosis of water down a water potential gradient. Active transport against a concentration gradient using ATP via a protein carrier. Co-transport of 2 different substances using a carrier protein.

  
• What is Facilitated diffusion? ( It involves the use of carrier and channel proteins. Polar molecules cannot pass by simple diffusion.)

  Facilitated diffusion refers to the transport of polar molecules and ions into and out of a cell.
• What is co-transport?

  Coupled movement of substances across a cell membrane via a carrier protein. Two types of molecule are moved across the membrane at the same time. The movement of one is dependent on the movement of the other
• Function of glycoproteins and glycolipids?

  Glycoproteins and glycolipids are receptors on the cell surface membrane which receive signals such as hormones from neighboring cells
• Name and describe 5 ways substances can move across a cell-membrane and into a cell (1)

  Active transport - transports substance using a carrier protein against a concentration gradient which requires ATP
• Name and describe 5 ways substances can move across a cell-membrane and into a cell (2)

  Facilitated diffusion- Substances are transported down a concentration gradient by a carrier protein/channel
• Name and describe 5 ways substance can move across the cell-surface membrane into a cell(3)

  Co-transport- Glucose and amino acids are drawn into cells by sodium ions from the sodium potassium pump
• Name and describe 5 ways substances can move across cell-surface membranes into a cell (4)

  Diffusion - Small non-polar molecules are diffused against a concentration gradient
• Name and describe 5 ways substances can move across cell-surface membranes into a cell (5)

  Osmosis- water is transported down a water potential gradient