DO NOW!! What is the function of the contractile vacuole? How does this help osmo- regulation? What is a centriole? What process are they involved in? Name three organelles limited to unicellular organisms? 12 Bio 2011 Matching definitions of organelles 1.Nucleus 2.Endoplasmic reticulum 3.Eye spot 4.Contractile vacuole 5.Cell wall 6.Golgi apparatus 7.Cillia 8.Centriole A.Packaging, modification and distribution of proteins B.Vacuole regulating water balance in protozoans C.Found in plant cells, a rigid structure outside the cell membrane, composed of cellulose D.Series of membranes attached to the nucleus, often associated with ribosomes E.Only found in animal cells, involved in cell division F.Allows autotrophic protists to sense the light G.Contains genetic material, controls the cell H.Hair-like projections in animal and protist cells that provide motility 12 Bio Nucleus 2.Endoplasmic reticulum 3.Eye spot 4.Contractile vacuole 5.Cell wall 6.Golgi apparatus 7.Cillia 8.Centriole A.Packaging, modification and distribution of proteins B.Vacuole regulating water balance in protozoans C.Found in plant cells, a rigid structure outside the cell membrane, composed of cellulose D.Series of membranes attached to the nucleus, often associated with ribosomes E.Only found in animal cells, involved in cell division F.Allows autotrophic protists to sense the light G.Contains genetic material, controls the cell H.Hair-like projections in animal and protist cells that provide motility Transport processes 12 Bio 2011 Active transportPassive transport Movement of materials down a concentration gradient No energy needed Movement of materials against a concentration gradient Requires energy membrane 12 Bio 2011 DIFFUSION Refers to the movement of particles in liquids and gases where the particles move randomly from an areas where they are in HIGH concentration to an area where they are in LOWER concentration INTO CELLS: FOOD AND OXYGEN OUT OF CELLS: CARBON DIOXIDE AND WASTE PRODUCTS 12 Bio 2011 Concentration Gradients These occur from a region of high concentration to a region of low concentration. The greater the difference in concentration the FASTER the rate of diffusion. Small particles diffuse FASTER than larger particles 12 Bio 2011 Factors affecting Diffusion Temperature Size of particles The size of concentration gradient 12 Bio 2011 DIFFUSION IN CELLS 12 Bio 2011 FACILITATED DIFFUSION? Evidence suggests that plasma membrane contains proteins which help (facilitate) the diffusion of substances Increases speed of certain substances 12 Bio 2011 Structure of plasma membranes Contains lipids called phospholipids in two layers (a lipid bilayer) Contains cholesterol Contains integral membrane proteins: receptors for hormones transport proteins (ion channels etc.) structural proteins Forms a semi-permeable barrier for the transport of materials due to the nature of the phospholipids in the membrane phospholipidsmembrane 12 Bio 2011 Structure of a plasma membrane 12 Bio 2011 Structure of a plasma membrane Diffusion Practical Write up and graph and look at sentence structure 12 Bio 2011 General rule Cells are limited to a certain size. Generally cells are so small we need a microscope to see them. We dont see cells the size of whole plants. Copy Rule 12 Bio 2011 WHY?? Complete the experiment to find the answer! ALL DOING THIS FOR THE FIRST TIME SO READ ALL INSTRUCTIONS CAREFULLY!!! 12 Bio 2011 Examples a-vsoln.htm 12 Bio 2011 Surface Area to Volume Ratio This ration SA/V gives a comparison of surface area to volume Greater rate of activity with an increase in SA/V ratio Cell organelles: folding of cristae in mitochondria allows respiration to occur more quickly Organ level: Villi - small projections from intestine increase SA Organism level: native Africans are generally tall and thin, allowing rapid heat loss to stop overheating 12 Bio 2011 Cell Size and Shape Size and shape are limited by The distance materials must travel inside the cell The number of places at which materials can enter the cell The distance materials must travel can be reduced by Cells having centres which do not require an exchange of materials Cells dividing to form two news cells 12 Bio 2011 What is it?? 12 Bio 2011 Osmosis is... The movement of water molecules from an area of lower to higher solute concentrations through a semi-permeable membrane 12 Bio 2011 Also described as... The movement of water molecules from an area of high water concentration (low solute conc.) to an area of low water concentration (high solute conc.)through a semi-permeable membrane 12 Bio 2011 Osmosis cont... Osmosis is a type of passive transport. Water moves freely through pores in the semi-permeable membrane. 12 Bio 2011 Dialysis tubing expt. In groups of three conduct an experiment with dialysis tubing and golden syrup to observe osmosis in action Look at the example from Mrs H and create your own 12 Bio 2011 Cells in solutions or external environments Words you NEED to know Isotonic Hypertonic Hypotonic 12 Bio 2011 HYPOTONIC Hypotonic Solutions: contain a low concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypotonic solution, the water diffuses into the cell, causing the cell to swell and possibly explode 12 Bio 2011 HYPERTONIC Hypertonic Solutions: contain a high concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to shrivel. 12 Bio 2011 Isotonic The concentration of solute in the solution can be equal to the concentration of solute in the cells. The cell is in an isotonic solution. (iso = same as normal) 12 Bio 2011 Explanations!! Explain to your neighbour the concept of osmosis and isotonic, hypertonic, and hypotonic then write your own paragraph in your books Use Bayley pg to answer the following questions What does plasmolysed mean? What happens if plants loose too much water? How do single celled organisms cope with water regulation? How do freshwater fish cope? How do fish keep osmoregulation? 12 Bio 2011 DIFFUSION Refers to the movement of particles in liquids and gases where the particles move randomly from an areas where they are in HIGH concentration to an area where they are in LOWER concentration INTO CELLS: FOOD AND OXYGEN OUT OF CELLS: CARBON DIOXIDE AND WASTE PRODUCTS 12 Bio 2011 Concentration Gradients These occur from a region of high concentration to a region of low concentration. The greater the difference in concentration the FASTER the rate of diffusion. Small particles diffuse FASTER than larger particles 12 Bio 2011 ACTIVE TRANSPORT This is the movement of substances (molecules and ions) from an area of LOW concentration to an area of HIGH concentration. MOVEMENT AGAINST THE CONCENTRATION GRADIENT REQUIRES ENERGY 12 Bio 2011 Examples active transport Ion pumps Active pumping of ions against a concentration gradient (e.g. Na +, K + ) Endocytosis: Phagocytosis: ingestion of solids Pinocytosis: ingestion of liquids Exocytosis Expelling of substances from the cell 12 Bio 2011 BIG PROCESSES! Small process Examples of transport 12 Bio 2011 Summary transport processes 12 Bio 2011 Transport Passive transport - No energy required - Driven by diffusion - Movement down a conc. gradient Active transport - Energy required - Movement against a conc. gradient Diffusion Facilitated diffusion Osmosis - Water only Ion pumps Exocytosis Endocytosis Entering cell: Phagocytosi s and pinocytosis