Cell Transport Review • Grab your folder and a highlighter on your way to your assigned seat. • Take out something to write with.
Cell Transport A process that helps cells maintain homeostasis. It involves the movement of molecules across the cell membrane. Two types: Passive and Active
Homeostasis • The process of maintaining a stable internal environment, even while the external environment is changing. • A state of balance – equilibrium
Cell Membrane • Identify the following: • Phospholipids • Proteins • Hydrophobic tails • Hydrophilic heads The Cell Membrane’s key function is to regulate particles moving in and out of a cell. Small particles may move through the phospholipid bilayer, while other particles must pass through a transport protein.
Concentration Gradient • The difference between the concentration of solutes in solutions. • Natural flow is from high to low. (with the concentration gradient)
Passive Transport Process by which molecules move with their concentration gradient. Molecules move from high to lowconcentrations. Passive Transport which does NOT require energy
Simple Diffusion An example of passive transport in which molecules move from areas of high concentration to areas of low concentration until homeostasis is reached.
Facilitated Diffusion • Diffusion with the assistance of a transport protein. • Occurs when the molecule is too large or polar.
Passive Transport – Osmosis • Type of passive transport • Process in which WATER molecules moving across a permeable membrane. H2Osmosis
How Does Osmosis Work? • WATERalways moves from the side with more watertothe side with less water. • In other words, water will always move to the side that has a higher concentration of solutes. Which side of the tube will the water rise?
Isotonic Solution • A solution that has the SAME AMOUNTof water as the cell. • Will this cell to shrink, swell, or stay the same size?
Hypotonic Solution • A solution that has MORE WATERthan the cell. • Will this cell to shrink, swell, or stay the same?
Hypertonic Solution A solution that has LESS WATERthan the cell. Will this cell swell, shrink, or stay the same?
How to do Osmosis predictions Tape or glue these steps in your lapbook below your 3 small sticky notes on the passive transport side. • Draw a picture if one is not provided. • Identify the values that are given. • Calculate the percentage of water by subtracting the solute percentage from 100. • Identify where the water concentration is HIGHER. • Draw arrows going from high to low water concentration.
Which direction will water move across the plasma membrane? Will the cell shrink or swell? High H20 Low H20 98% Water 88% Water Cell/Plasma Membrane
Which direction will water move across the plasma membrane? Will the cell shrink or swell? High H20 Low H20 60% Water 75% Water Cell/Plasma Membrane
Which direction will water move across the plasma membrane? Will the cell shrink or swell? 50% Water 50% Water Cell/Plasma Membrane
Which direction will water move across the plasma membrane? Will the cell shrink or swell? High H20 Low H20 30% Solute 50% Solute Cell/Plasma Membrane HINT: Subtract the percent of salt from 100% to get the percent of WATER.
Low H20 High H20
Low H20 High H20
High H20 Low H20
Recap – PASSIVE TRANSPORT 3 Characteristics • HIGH TO LOW • NO ENERGY • WITH concentration gradient 3 Types • Simple Diffusion: Movement of particles WITHOUT the assistance of a PROTEIN • Facilitated Diffusion: Must be assisted by a PROTEIN • Osmosis: Movement of WATER molecules ONLY
Active Transport • Process by which particles move AGAINST their concentration gradient • Requires ENERGY • Movement from molecules is from an area of LOW concentrations to HIGH concentrations.
Sodium-Potassium Pump (Na+/K+pump) • Naturally, Sodium (Na+) and Postassium (K+) ions diffuse across the cell membrane, WITH the concentration gradient, which DOES NOT require energy. • The Na+/K+ pump reverses this process sending Na+ ions out of the cell and K+ ions into the cell AGAINST the concentration gradient, which REQUIRES energy (ATP)., from a low to a high ceontration. Would there be a need for Na+/K+ pump the Na+ and K+ ions were not continuously diffusing across the cell membrane? Why or why not?
Active Transport • 2 types of active transport: Endocytosis Exocytosis • Can you figure out what each terms means?
EndocytosisCell membrane folds inwards moving substances INTOthe cell Receptor-mediated endocytosis: uptake of substances by the cell is targeted to a single type of substance that binds at the receptor on the external cell membrane Phagocytosis: the cell membrane surrounds the particle and pinches off to form an intracellular vacuole Pinocytosis: the cell membrane surrounds a small volume of fluid and pinches off, forming a vesicle
Exocytosis Exocytosis: a vesicle migrates to the cell membrane, binds, and releases its contentsmoving substancesOUTof the cell
ACTIVE TRANSPORT: • * ENERGY required • * LOW TO HIGH • * AGAINST con. gradient • Examples: • Endocytosis • Exocytosis • Sodium-Potassium pump PASSIVE TRANSPORT: * NO ENERGY required * HIGH TO LOW * WITH con. gradient Examples: Diffusion Facilitated Diffusion Osmosis Passive vs. Active Transport ANALOGY:
Recap – ACTIVE TRANSPORT 3 Characteristics • LOW TO HIGH • ENERGY REQUIRED • AGAINST concentration gradient 3 Types • Protein Pumps: Movement of particles WITH the assistance of a PROTEIN • Endocytosis: Particles ENTERING the cell • Exocytosis: Particles EXITING the cell
CELL TRANSPORT REVIEW In the space at the left, write “T” if the statement is true, and write “F” is the statement is false. If the statement is false, change the italicized term to make the statement true. 1.____ A solution in which the concentration of dissolved substances (solute) outside the cell is lower than the concentration inside a cell is hypertonic. 2._____ In passive transport, the movement of particles across a membrane requires energy. 3._____ Endocytosis is a process by which a cell membrane surrounds and takes in material from the environment. 4._____ The passive transport of material across a membrane by means of transport proteins is called activated diffusion. 5._____ A membrane that allows only some materials to pass through shows selective permeability F F T F T
Circle the word or phrase that best completes the statement or answers the question. 1. The structure most responsible for maintaining cell homeostasis is the – cytoplasm cell wall mitochondria plasma membrane 2. A plasma membrane is made up of a(n) – cholesterol layer enzyme layer lipid bilayer protein layer 3. Which of the following is not a form of passive transport? facilitated diffusion diffusion endocytosis osmosis 4. Diffusion continues until – equilibrium is reached turgor pressure is reached one side has more 5. If a cell is placed in salt water, water leaves the cell by — osmosis diffusion active transport phagocytosis 6. A cell moves particles from a region of lesser concentration to a region of greater concentration by – facilitated diffusion osmosis passive transport active transport
Use the pictures on the top to answer the questions on the right. a. Which side has the higher concentration of glucose? extracellular space intracellular space b. Which way will the glucose move? into the cell out of the cell c. Does this require energy? yes no d. Which type of transport is this? active passive e. What specific type of transport is this? diffusion endocytosis