The cell membrane One of the most important parts of the cell is its Membrane, which separates the cell from its surroundings. All cells are surrounded by a thin flexible barrier known as the Cell Membrane. The cell membrane Controls what comes out and in of the cell. It also provides protection. The composition is a double layered sheet called a Bi-lipid layer. This lipid bi-layer is made up of two layers of Lipids (fats)

The cell membrane The lipid bi-layer is what gives cell membranes a unique structure that forms a strong barrier between the cell and its surroundings. In addition to lipids most cell membranes contain Protein molecules that are embedded in the lipid bi-layer. There are also receptor molecules that are attached to the protein molecules.

Protein Channels The proteins act as pumps and channels moving materials into and out of the cell and act as receptor molecules for any hormone or other chemical message that need to get into the cell. The carbohydrates act like chemical Reading cards allowing cells to communicate with each other.

Look at the roots of the protein labels (hydrophilic & hydrophobic) Look at the roots of the protein labels (hydrophilic & hydrophobic). What do you think they mean?

Passage of materials through the cell membrane… What does the cell membrane do? 1. It protects the cell 2. It allows things in and out of the cell 3. It is Semi-Permeable (not everything can get across it) 4. It has 2 layers (It is like a protein sandwich) 5. The proteins are for transporting things across LIPID PROTEIN

DIFFUSION Diffusion is the movement of materials from a high concentration to a low concentration until there is equilibrium (no energy is used to do this).

Why does diffusion occur? The reason for this is so all the molecules can be in equilibrium. Diffusion can also only occur across a cell membrane if there is a concentration gradient. (This is when material is higher on one side of the membrane than on the other).

Facilitated Diffusion is when protein channels in the cell membrane help the movement of molecules across the membrane. Osmosis is the diffusion of Water across a membrane from High to low concentration. [[No Energy used]]

Diffusion low  high inside cell fat fat fat fat outside cell fat fat Which way will fat move? inside cell fat fat fat low high  fat outside cell fat fat fat fat fat fat

Diffusion sugar sugar sugar sugar sugar sugar  sugar sugar sugar Which way Will sugar Move? sugar low  high sugar sugar sugar sugar sugar

What are the effects of Osmosis? If you place a cell in a solution (mixture of 2 substances) three things can happen: 1. ISOTONIC SOLUTION When the concentration of water is the same inside and outside cell 2. HYPOTONIC SOLUTION When there is a higher concentration of water outside cell, so water moves into cell 3. HYPERTONIC SOLUTION When there is a higher concentration of water inside cell, so water moves out of cell

Isotonic Solution Isotonic Solution Balanced conditions no difference between cell & environment example: blood problem: none water flows across membrane equally, in both directions volume of cell doesn't change

Hypotonic Solution Hypotonic Solution Freshwater a cell in fresh water example: Paramecium problem: gains water, swells & can burst water continually enters Paramecium cell solution: contractile vacuole pumps water out of cell

Hypertonic Solution Hypertonic Solution Saltwater a cell in salt water example: shellfish problem: lose water plasmolysis in plants shrinking cell solution: take up water

Methods of Transport Passive transport: movement from High to low concentration. No energy is used. This is also called Simple diffusion Active transport: movement from low to high concentration. A. needs energy B. opposite of simple diffusion

Now add the following words to your explanation: Active Transport Analyze this animation. Explain what you see happening. Now add the following words to your explanation: Solution Molecules Cell membrane Protein channel ATP Active Transport High concentration Low concentration

Do the animations below portray active or passive transport Do the animations below portray active or passive transport? How do you know? SIMPLE DIFFUSION Move from HIGH to LOW concentration “passive transport” no energy needed

Do the animations below portray active or passive transport Do the animations below portray active or passive transport? How do you know? ACTIVE TRANSPORT Cells may need molecules to move against concentration difference need to pump “uphill” from LOW to HIGH using ATP protein pump requires energy ATP ATP

Transport Summary diffusion facilitated diffusion active transport Analyze the three forms of transport across a membrane below. Identify and Explain the forms of transport for each red arrow! diffusion facilitated diffusion ATP active transport

Transport Vocab Pinocytosis- cell drinking-engulfing small particles. Phagocytosis- cell engulfing- Lysosomes fuse with a bacteria for digestion Cyclosis- Movement of the cytoplasm