Cellular Transportation Question: Will exercising increase the oxygen-rich air out of my lungs slowly? Hypothesis: If I do/ do not exercise for a minute then the oxygen-rich air will leave my lungs fast/slowly. What is Cellular Transportation Passive transport is the transportation of materials across a plasma membrane without energy. Active transport is the movement of particles from an area of low concentration to an area of high concentration that uses energy provided by ATP or a difference in electrical charges across a cell membrane. What is passive transport • With the concentration gradient – from higher concentration to lower concentration • Requires no energy Passive Transport Passive transport can occur by (A) simple diffusion, (B) facilitated diffusion by channel proteins, and (C) facilitated diffusion by carrier proteins. What is Diffusion of Water • The plasma membrane controls what can enter or leave a cell. • The plasma membrane does not limit the amount of water that passes or diffuses through. • Remember… diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. It is a natural result of kinetic molecular energy. What is a solution, solute, and solvent? Solution is a type of mixture in which all the components are evenly distributed. Example Kool- Aid Drink Solute is a substance that is dissolved in a solution Example Kool-Aid powder Solvent is dissolving substance in a solution. Example the water to make Kool- Aid. What is Osmosis • The diffusion of water across a selectively permeable membrane is called osmosis. • In other words osmosis is the movement of water or another solvent through a permeable membrane from an higher concentration to an area of lower concentration What controls osmosis? • Regulating water flow through the plasma membrane is important to maintaining homeostasis. • If a strong solution and a weak solution of the same things are put in direct contact, the water molecules will diffuse in one direction. • The water will go toward the stronger side until the concentration is the same everywhere. The water wants to go to the area of higher concentration (the stronger solution) What is selective permeability like? like a screen Some things can come in and some things are kept out 24 sugar 24 sugar molecules on molecules on 6 sugar molecules this side this side on this side 6 sugar molecules on this side During osmosis, water diffuses across a selectively permeable membrane. Notice that the number of sugar molecules did not change on each side of the membrane, but the number of water molecules on either side of the membrane did change. What is isotonic solution • Same concentration on both sides • Diffuses in and out at the same rate • Cells retain their normal shape Cells in an isotonic solution – neutral …same concentration on both sides In an isotonic solution, water molecules move into and out of the cell at the same rate, and the cells retain their normal shape as in (A). Notice the concave (normal) disc shape of a red blood cell in (B). A plant cell has its normal shape and pressure in an isotonic solution in (C). Put the fish in an isotonic solution It would be like putting a freshwater fish in a freshwater fish tank… Put the fish in an isotonic solution The fish would stay the same size. Cells in a hypotonic solution • Concentration of dissolved substance is lower in the solution outside the cell • There is more water outside the cell • Cells in hypotonic solutions experience osmosis that FLOWS IN • The cell swell and internal pressure increases Cells in an hypotonic solution – concentration of dissolved molecule lower outside the cell In a hypotonic solution, water enters a cell by osmosis, causing the cell to swell (A). Animal cells, like these red blood cells, may continue to swell until they burst. (B). Plant cells swell beyond their normal size as pressure increases (C). Put the fish in an hypotonic solution It would be like putting a saltwater fish in a freshwater fish tank… Put the fish in an hypotonic solution The fish would swell… it may even burst! What is hypertonic solution • The concentration of dissolved substances is higher outside the cell than inside the cell • Cells in hypertonic solutions experience osmosis that causes water to FLOW OUT • Animal cells shrink in hypertonic solutions because of decreased pressure • Plants wilt under these conditions Cells in an hypertonic solution – concentration of dissolved molecule higher outside the cell In a hypertonic solution, water leaves a cell by osmosis, causing the cell to shrink (A). Animal cells like these red blood cells shrivel up as they lose water (B). Plant cells lose pressure as the plasma membrane shrinks away from the cell wall (C). Put the fish in an hypertonic solution It would be like putting a freshwater fish in a saltwater fish tank… Put the fish in an hypertonic solution The fish would shrivel like a raisin. What is the direction of osmosis Hypotonic Hypertonic Isotonic Solute higher Solute Solute is equal inside cell than molecules inside and outside higher outside outside of the cell than inside cell Water tends to flow from hypotonic to hypertonic solutions Salt sucks… if you are a slug… is it a hyper or hypotonic environment for the slug? Remember…Higher concentration on the outside = ? What is concentration? What is concentration gradient? Concentration is the measure of the amount or proportion of a given substance with combined with another substance. Concentration gradient is the graduated differences in concentration of a solute per unit distance through a solution. What is an example of concentration gradient • This diagram shows a “concentration gradient”. • There is a higher concentrate of dissolved particles on one side. Concentration gradient • When we move from areas of higher concentration to lower concentration, we are moving with the gradient. • When we move from areas of lower concentration to higher concentration, we are moving against the gradient. What is facilitated diffusion? • Facilitated diffusion is a process in which substances are transported across a plasma membrane with the concentration gradient with the aid of carrier (transport) proteins. IT DOES NOT REQUIRE ENERGY! What is passive transport by proteins • Transport proteins in plasma membrane help or “facilitate” movement of substances through the membrane • This movement is with the concentration gradient • It requires no energy What are carrier proteins? Carrier proteins are proteins embedded in the plasma membrane involved in the movement of ions, small molecules, and macromolecules into and out of cells. Carrier proteins are also known as transport proteins. 18 Examples of diffusion Humans obtain their oxygen by diffusion But not through the skin Although the skin is well supplied with blood vessels, there are too many layers of cells for diffusion to be fast enough Humans have lungs and it is in these lungs that diffusion occurs Earthworm 16 diffusion takes place through the thin skin of the worm CO2 diffuses O2 diffuses in out Section through worm’s skin 0.04mm the blood vessels absorb the O2 and carry it to the body Human lungs 19 windpipe lung diaphragm position of lungs heart in thorax human lungs Lung Structure 20 each tube ends up in a cluster of tiny air sacs. the air passages in the lung branch into finer and finer tubes A single air sac 21 blood supply to air sac diffusion of oxygen air breathed in and out diffusion of carbon dioxide O2 CO2 0.03 mm question 4 Fish 23 gill cover gills gill filaments gill cover cut away Leaf 26 O2 and CO2 diffuse through pores in the the ‘veins’ epidermis bring water In a thin leaf, the diffusion distance O and CO diffuse is short 2 2 into the spaces between cells 22 In mammals, birds, reptiles and amphibia, oxygen and carbon dioxide are exchanged by diffusion in the lungs In fish, this exchange of gases takes place by diffusion through the gills The oxygen dissolved in the water diffuses into the blood vessels in the gills. Plants 25 Plants have no special organs for breathing They have to rely on diffusion for their supplies of oxygen and carbon dioxide There are pores in the leaves and stems through which the gases diffuse In daylight, CO2 (for photosynthesis) will be diffusing in and O2 will be diffusing out In darkness, O2 will diffuse in and CO2 will diffuse out as a result of respiration What is active transport • Cells can move substances from areas of lower concentration to areas of higher concentration • This is moving against the concentration gradient • This will require extra help from carrier proteins • Energy is needed! How does active transport occurs • A particle binds with a carrier protein – usually pretty specific (like a lock and key) • When the correct ones fit, chemical energy allows the cell to change the shape of the carrier protein like opening a door. • Once the particle is on the other side, the carrier protein goes back to its normal shape. When are carrier proteins used? Carrier proteins are used in active transport to pick up ions or molecules from near the cell membrane, carry them across the membrane, and release them on the other side. Why does active transport require energy? Molecules tend to move from higher to lower concentration. Active transport reverses the trend requiring energy input. What are two types of bulk transport? Endocytosis & exocytosis What is endocytosis? • Endocytosis = cells surrounds and takes in materials from its environment. Endocytosis A process in which a cell engulfs extracellular material through an inward folding of its plasma membrane. • Some single cell organisms like amoebas eat this way.