Chapter 2, Lesson 3 Moving Cellular Material How do materials enter and leave cells? How does cell size affect the transport of materials?

Lesson 3 Vocabulary Passive transport Diffusion Osmosis Facilitated diffusion Active transport Endocytosis exocytosis

Quick Review of properties of the Cell Membrane Forms the boundary between cells and between organelles Controls the movement of substances into and our of cells How it does this depends on: Physical properties of the substance passing through Chemical properties of the substances passing through Semipermeable – will allow only certain substances to enter or leave a cell

Transporting Substances happens in 2 main ways: I. Passive Transport II. Active Transport The movement of substances through a cell membrane WITHOUT USING THE CELL’S ENERGY The movement of substances through a cell membrane only BY USING THE CELL’S ENERGY

I. Passive Transport When can a cell move substances across the cell membrane using passive transport? 1. If the molecules are small 2. When there are MORE molecules of a substance on one side of the membrane than on the other side

Types of Passive Transport Diffusion – the movement of substances from an area of higher concentration to an area of lower concentration Osmosis – the diffusion of WATER molecules through a membrane Facilitated Diffusion – when molecules pass through a membrane using special proteins called transport proteins

Assignment for tomorrow: Read pages 62-65. Label and answer the following questions in your notebook. Please write in complete sentences and re-state the questions. VC-p. 62 RC-p. 63 KCC-p. 64 KCC-p. 65

The water on the right side would remain clear. “What would the water in the beaker on the right look like if the membrane did notlet anything through?” VC-p. 62 The water on the right side would remain clear. Think about these questions: How would you describe the concentration of red dye molecules on each side of the membrane in the first beaker? Why did the dye molecules move into the right side of the beaker? What would the beaker look like if there was another picture taken after 60 minutes? Why?

“How do materials move through the cell membrane in facilitated diffusion?” RC-p. 63 Transport proteins called channel proteins and carrier proteins move materials through the cell membrane in facilitated diffusion.

Facilitated Diffusion Used when molecules are too large or chemically unable to travel through a cell membrane Does NOT require cell to use energy Transport proteins are used to get the molecules across Two types of transport proteins Carrier proteins Channel proteins

2 Types of Transport Proteins Carrier Proteins – “think ferry boat” Channel Proteins – “think tunnel” Carry large molecules through the cell membrane Form pores through the cell membrane

II. Active Transport The movement of substances through a cell membrane only BY USING CELL’S ENERGY Second way materials can pass into or out of a cell Used when moving substances from areas of LOWER CONCENTRATION TO HIGHER CONCENTRATION

2 Types of Active Transport Endocytosis Exocytosis The process during which a cell takes IN a substance by surrounding it with the cell membrane The process during which a cell’s vesicles release their contents OUTSIDE the cell https://www.youtube.com/watch?v=DuDmvlbpjHQ

“How do materials enter and leave cells?” KCC-p. 64 Materials enter and leave cells through the cell membrane using either PASSIVE TRANSPORT, such as diffusion, osmosis or facilitated diffusion; OR ACTIVE TRANSPORT, including endocytosis and exocytosis.

“how does cell size affect the transport of materials?” KCC-p. 65 As a cell becomes larger, its volume increases faster than its surface area, making the transport of enough materials to support the cell more difficult.

Milk can be easily transported in this picture As the size of the community grows, it gets much harder to transport milk to the whole community

By splitting up the community, milk can, once again, be transported efficiently