Answer in comp book… 1.The process by which water passes into or out of a cell is called? 2.The dispersal of ink in a beaker of water is an example of? 3.Ion channels serve as: a.Passageways b.Information receivers c.Cell identifiers d.Food molecules 4. Diffusion takes place from an area of _______ concentration to an area of __________ concentration. 5. A calcium ion channel will allow: a.Only calcium ions to pass b.Any kind of ion to pass c.Positive ions to pass d.None of the above

Active Transport Chapter 5 Section 2

Active Transport Movement of contents up their concentration gradient. – Movement from lower concentration to a higher concentration Requires energy

Cell Membrane Pumps Remember Ion Channels and Carrier Proteins?? These proteins are used in passive transport, but can also be used in active transport. Called “pumps” because they move substances from lower to higher concentration. Similar to proteins in facilitated diffusion except use energy.

Sodium-Potassium Pump Some cells must have a higher concentration of sodium outside the cell and higher concentration of potassium inside the cell. P. 104

Quick… The sodium-potassium pump usually pumps. a.Sodium into the cell b.Potassium into the cell c.Only a potassium and sugar molecule together. d.Potassium out of the cell.

Movement in Vesicles When molecules are too large to pass through the cell membrane through the previously discussed transport. Endocytosis vs. Exocytosis

Endocytosis Where cells ingest external substances. Cell membrane surrounds substances and pinches off to move to the inside of the cells. Types of endocytosis: – Pinocytosis: movement of solutes or fluids – Phagocytosis: movement of larger particles or whole cells. (many unicellular organisms feed via phagocytosis while animals may use it to ingest harmful substances)

Exocytosis Process where substances are expelled from inside the cell to the Reverse of endocytosis Used to release: larger molecules: proteins, waste products, or toxins.