Transcript Bell Work
Bell Work 1. If a membrane allows movement of only certain materials, it is called ___. a. Somewhat permeable b. Selectively permeable c. Somewhat impermeable d. Selectively permeable Notes: Cell Membrane • Cell membranes are also called plasma membranes • Facts: – Selectively permeable • Allows certain materials to move in and out of the cell when needed, but keeps other material from crossing the membrane – Made of phospholipid bilayer • Water soluble phosphate head (hydrophilic) • Water insoluble fatty acid tail (hydrophobic) – Has various carbohydrates, proteins and cholesterol mixed into the bilayer Question 1. Which of these is NOT a type of cellular transport? a. endocytosis b. exocytosis c. diffusion d. nucleocytosis Question 2. a. b. c. d. The cell membrane is made primarily of ___. carbohydrates Nucleic acids proteins phospholipids Question 3. a. b. c. d. When active transport is used, the cell ______. Does not use any of its own energy Uses some of its own energy Uses energy from other cells Uses the energy stored mainly in the nucleus Question 4. a. b. c. d. During passive transport, a cell ________. Does not use any of its own energy Uses some of its own energy Uses energy from other cells Uses the energy stored mainly in the nucleus Notes: Cellular Transport • Diffusion – Movement of molecules from an area of higher concentration to an area of lower concentration. • Passive Transport – It does not require energy » Oxygen and Carbon Dioxide use diffusion » Not all molecules can enter and leave by diffuison » Once equilibrium is reached they stop Notes: Cellular Transport Concentration Gradient – The name of the difference that exist when there is a difference in concentration in two areas Equilibrium – When the concentration on both sides of the cell membrane are equal Draw Concentration Gradient Notes: Facilitated Diffusion • Transport Proteins – Allow some of the ions, sugars, and amino acids to pass through from an area of high concentration to an area of low concentration – Many different types – Each selective for a specific molecule – Form of PASSIVE TRANSPORT Questions Why is diffusion a type of passive transport? • A. It moves materials across a cell membrane • B. It does not require any of the cell’s energy • C. It does not need activation by an enzyme • D. It continues until equilibrium is reached Questions During diffusion, molecules move _____. • A. from an area of higher concentration to an area of lower concentration • B. from an area of lower concentration to an area of higher concentration • C. across a cell membrane with the use of cellular energy • D. against a concentration gradient Notes: Osmosis • Osmosis – Passive transport – Moves molecules down a concentration gradient • 2 Facts – Always a movement of water molecules – Moves water molecules across a selectively permeable membrane through which the solute (dissolved particles) cannot cross Notes: Osmosis • Osmosis – Solute particles are too large to pass through the selectively permeable membrane • Like oil and water’s inability to mix, particles that are water soluble cannot pass through the middle of the membrane – To bring about equilibrium, either facilitated diffusion or osmosis must take place Notes: Isotonic Solution • Isotonic – The solution on the outside of the membrane has the same concentration as the solution on the inside of the membrane – No net movement of water molecules across the membrane Notes: Hypertonic Solution • Hypertonic – The solution outside the membrane contains less water and more solute than the solution inside the membrane • water rushes out of the cell • Cell shrivels up • Example: salt on a slug Notes: Hypotonic Solution • Hypotonic – Solution on the outside of the cell membrane has a greater concentration of molecules than the solution inside the cell • More water on the outside • Ex. Wilted vegetable (celery) • Water rushes in an the cells swell Notes: Active Transport • Active Transport – Used to move molecules against a concentration gradient – Requires Energy • 3 Types of Transport Proteins help move substances in and out of the cell channel proteins carrier proteins gate proteins Notes: Transport Proteins • Often the protein has a certain shape that allows it to stick to a molecule with a matching shape • Uses chemical energy to move against the gradient Notes: Endocytosis • Endocytosis – A way of allowing particles that are too big to cross the cell member to enter – Particle is enclosed with material from the cell, then pulled into the cell – In = En • Into the cell = ENDOcytosis Notes: Exocytosis • Exocytosis – Used to get rid of large particles • Undigested food, waste products or hormones – Material is enclosed in a vesicle • Vesicle meets the cell membrane, breaks open, then fuses with the membrane • Particles are released to the outside of the cell Exit the cell = EXocytosis