The Cell Membrane and Homeostasis What is the cell membrane? A quick review A. Cell Membrane and Cell Transport. Unit 2: Cells and Cell Transport

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1 Unit 2: Cells and Cell Transport Cell Membrane and Cell Transport Name: Directions: Go to and on the Biology page, find the document labelled Cell Membrane and Cell Transport and use the information it has to fill out this paper. Warm-Up Stations: Station 1 Which object or materials are made up of cells or were once made of cells? Station 2 Each function below is performed by plants, animals, or both. Write each example into the correct column. Plant 1) Animal 1) Both Station 3 Which things are typically larger than a normal plant or animal cell? Station 4 Write down the best answer here: The Cell Membrane and Homeostasis What is the cell membrane? A quick review A. B. C. Cell membrane is made mostly of 2 main organic molecules:. The cell membrane to pass through while others from passing through. Other names for the cell membrane: - -Phospholipid bilayer = Phospholipid= Bilayer= -Semi-permeable= -Semi= -Permeable=

2 Cell Membrane Composition Phospholipid Bilayer (lipid bilayer) 2 layers of Proteins are in the bilayer chains are attached to the proteins So many kinds of molecules = The Membrane is very flexible because of the fatty acid chains and the membrane has all of the structures listed inside of it so we call it a Fluid Mosaic Model Fluid because Mosaic because Cell Membrane Properties and Functions Selectively permeable = only certain molecules can free pass across the membrane Only small, uncharged, polar molecules can pass freely E.g. Large molecules and ions are impermeable = Protein Function in Cell Membrane 1. Surface Proteins receptors that provide 2. Transport Proteins help transport Carbohydrate Function in Cell Membrane Serves as identifiers allowing individual cells to Homeostasis: Maintaining a constant internal. Plants and animals regulate things like:, water,, glucose,, etc. The cell controls what goes and = maintaining homeostasis! Concentration gradient: the in the of across the. Cellular Transport: Maintains in the.

3 Match the cell organelle with its function! 1. Cell membrane A. Controls what goes in and out of the cell 2. Cell wall B. Storage 3. Nucleus C. Makes ATP 4. Ribosome D. Offers support and protection Unit 2: Cells and Cell Transport 5. Mitochondria E. Makes Glucose 6. Chloroplast F. Contains DNA, controls all functions 7. Vacuole G. Makes proteins Cell Transport -Material moves in/out through the. -The cell membrane is. Types of Cell Transport Passive Cell Transport Active Cell Transport -Diffusion is the movement of molecules from. -An example of diffusion is:. -Osmosis is the movement of from. -An example of osmosis is:. Quick Review 1. Diffusion moves substances from to concentration. 2. Diffusion moves a concentration gradient. 3. The U-shaped tube in the figure is divided by a membrane that is impermeable to starch but permeable to water. In what direction will water move? -Facilitated diffusion is the movement of through a. -Active transport: uses (energy). -Movement of particles the concentration gradient ( ) Quick Review: Which cell process will move substances against a concentration gradient? Passive Type Diffusion What does it move? What direction does it move? Does it use energy? Does it use a protein? Osmosis Facilitated Diffusion Active Active Transport

4 Fill in the table below to compare and contrast PASSIVE and ACTIVE transport. Place an X in the boxes that apply. Diffusion Osmosis Facilitated Active Transport Diffusion Moves from HIGH to LOW Moves from LOW to HIGH Needs a protein Needs energy Moves particles Moves water Fill out the flow chart below. You may use the following words or phrases more than once: Simple diffusion, dynamic equilibrium, energy, no energy, high concentration, low concentration, osmosis, passive, active, facilitated diffusion, transport protein Movement across membranes can Can be which requires which requires and a The three types are In order to move particles from a region of They move particles from a region of to a region of to a region of Which results in

5 FLIP Homeostasis is one of the 8 characteristics of living things. Homeostasis is the maintenance of the internal environment within certain limits. Cells must maintain a number of limits. These include properties like temperature, salinity, ph, blood glucose level, the concentrations of other nutrients and wastes, and water balance. Temperature Enzymes have a small part called the active site where substrates bind and the chemical reaction takes place. Only molecules with the correct shape can fit with the enzyme. The shape of the active site is changed by heating the enzyme above a certain temperature. Then the molecules can no longer fit and the reaction cannot happen. ph A measure of the degree of the acidity or the alkalinity of a solution as measured on the ph scale of 0 to 14. Parts of the cells work best at specific phs. Glucose Concentration in the Blood Cells want to maintain the same glucose balance in and out of cells. When there is excess glucose that the cells do not want inside, it is stored in special cells in the liver or turned into lipids. Insulin, a hormone, helps regulate the amount of glucose in our blood. Water Balance The body s cells are bathed in water, and the correct water balance is crucial to life. Water crosses easily across most membranes. Cell membranes are what regulate things like ph, glucose, and water balance. Cells have semi-permeable membranes which allow some things to pass through but prevent other things from passing through. Cell membranes will allow small molecules like oxygen, water, carbon dioxide and glucose to pass through. Cell membranes will not allow larger molecules like starch and proteins to pass through. FLOP Name the properties that cells work to maintain through homeostasis: What would happen if your body did not maintain homeostasis? What is the term used to describe enzymes that no longer work due to temperature changes? Why does a cell need to maintain temperature and ph? What happens to excess glucose in the bloodstream? What molecules does the cell membrane let through? What molecules does the cell membrane prevent from passing through?

6 What structures do you see embedded in the cell (plasma) membrane? The cell membrane controls what goes in and what goes out of the cell. The movement of molecules across the membrane is called transport. There are different types of transport, but all molecules are moving in relation to a concentration gradient, a measure of how the concentration of particles changes from one area to another There are two main types of transport: Active and Passive. Active transport involves the use of energy. Substances are moved AGAINST the concentration gradient, from an area of LOW concentration to HIGH concentration. Active transport generally requires the use of protein pumps to move molecules. Passive Transport does not require energy. Substances are moved WITH the concentration gradient, from areas of HIGH concentration to LOW concentration. There are 3 types of passive transport: 1) Diffusion: Passive transport from high to low concentration 2) Osmosis: Diffusion of water through a selectively permeable membrane 3) Facilitated Diffusion: Passive transport of specific molecules (like glucose) across the membrane with the help of protein channels Sample Problem Label the area of HIGH and LOW concentrations. What is the major difference between active transport and passive transport? What is the relationship between diffusion and osmosis?(hint: what is the only substance that carries out osmosis?) Which of the following is NOT an example of active transport? I. Facilitated diffusion II. Osmosis III. Diffusion A. I only B. III only C. I and II only D. I, II, and III Where is there the highest concentration of water? water cell Cup of Which way will the water move? What will happen to the cell if it gains water? What will happen to the cell if it loses water?

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