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Englishcell2 po poprawie


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Englishcell2 po poprawie

  1. 1. 1 Biology lessons - subject cytology Summary: Presentation of the optical microscope, study of animal and vegetal cells using the microscope, generalization about the structure of animal and vegetal cells. Brief presentation of procaryotic cells. Structure of the cell membrane, different transportation mechnisms across this membrane.
  2. 2. 2 Lesson Course: Lesson 1 A. the light microscopeor optical microscope Presentation of the different parts and their use eyepiece and objective lenses: magnification Nosepiece: choice of objective Base and neck: manipulation, fixation of different parts Light source: illumination Focus: vertical movements of sample Iris diaphragm: controls how much light passes through the sample. Partially closing the diaphragm may increase contrast Condensor lens: concentrates light from the illumination source Stage and stage clips: serves to deposit and fix the sample Stage control: horizontal movements of sample ( Simple exercise with ready sample, no notes): Raise stage, choose smallest objective, center sample, lower stage until you see something, verify whether it is part of the sample by using the stage controls. If it is, focus, switch to next objective, focus, center, switch to 40x objective. )
  3. 3. 3 B. Structure of cells Homework given here so the students may already take notes : compare animal and vegetal cells 1. animal cells * observation of liver cells No notes: how to prepare a sample: use a microscope slide, touch the slide with a piece of liver, add water, add cover glass - observe and sketch As a conclusion: * structure of the animal cell Annotated sketch *** Lesson 2 * roles of different cell organites cell membrane: maintains integrity of the cell, partially controls incoming ant outgoing substances (see cell membranes), reacts with certain chemicals that attach to receptors in the cell membrane cell plasma: cell metabolism takes place here nucleus: contains genetic material, controls cell metabolism 2. structure of vegetal cells * Observation of onion cells Red onion cells: observe and sketch No notes, prepare slide and a drop of water, cut onion into pieces, locate slightly brilliant skin on the surfacel, cut small squares, take one out with pincers, put it into the drop of water, apply cover glass - observe and sketch For the quick students only: b. observation of waterweed cells (Elodea canadensis) no notes: put a tender young leaf into a drop of water… As a conclusion: * structure of the vegetal cell Annotated sketch * roles of different cell organites Nucleus, membrane, plasma: see animal cell cell wall: cell form, resistance to osmotic pressure (cf later in this chapter), deposit of waste products vacuole: contains reserve stock of certain substances, most importantly water, waste products
  4. 4. 4 tonoplast: delimitation of vacuole, controls transportation chloroplasts: photosynthesis = transformation of atmospheric CO to organic substances in the presence of light *** Lesson 3 Correction of homework Demonstration using the three potato pieces needed under C.2.c is started 3. procaryotic cells Bacterial cells do not contain a nucleus. Such cells are called procaryotic (before (the evolution of) a nucleus) cells. Cells containing a nucleus are called eukaryotic (cells with a real nucleus) cells. Show pictures Annotated sketch *** Lesson 4 C. Transportation through cell membranes 1. diffusion Demonstration: a few ink drops in a container of water will spread through the entire volume in less than an hour, even without stirring. At the end, the concentration of ink molecules is the same in the entire volume of water. This may be explained by the random brownian movement of the molecules in a fluid (= liquid or gaz) (Robert Brown, Scottish botanist discovered these movements in 1827 in observing moving particules inside dead pollen grains). He noticed the same kind of movements in all kind of finely ground substances in a fluid) Illustration of the phenomenon by computer animation 2. passive transportation of molecules through biological membranes N. B.: passive transportation - is based on diffusion - allows mvts according to the concentration gradient - has no energy cost a. structure of the biological membrane
  5. 5. 5 Source: Fluid mosaic model by Singer and Nicolson (1972) Annotations: phosphate, fatty acid chain, phospholipid, double bilayer, membrane proteins Hydrophile layer (x2), hydrophobe layer b. consequences for molecule transportation → Only small fat soluble (non-charged) molecules can cross the biological membrane by diffusion → big or polar molecules can cross membranes by using specialized membrane proteins called channel or transporter proteins. These are specific for the transported substance Different forms of passive transportation mechanisms: see picture Examples: O2 or CO2, Channel for sodium ions Transporter for glucose Source: http://susankannasjackiegunderson.wi
  6. 6. 6 Observation of the potato pieces Lesson 5 c. passive transportation of water molecules- osmosis * observation on a macroscopic level demonstration : using an apple corer, cut 3 pieces out of a potato, each the same size put one piece into distilled water, one into physiological serum, one into a 1M saline solution the potato piece in the distilled water increased in size: influx of water The potato in the physiological serum maintains its size: no water movement or equal movement in an out of the piece The piece in the salt solution decreased in size . efflux of water
  7. 7. 7 * observation on a microscopic level Observation of beef blood under the microscope - once in a drop of distilled water, - once in a drop of physiological serum, - once in a drop of 1M saccharose solution Observe, sketch, explain: Correction: sketches and cf potato, but replace piece of potato with cell *** Lesson 6 * events on a submicroscopic level Sketch of a biological membrane containing aquaporins separating two fluids, one containing little free water, the other containing more free water. Important movement from hypotonic to hypertonic solution, small movement in the other direction, net resultant. Remarks: - application of mechanical presure on hypertonic side: reduction or even inversion of osmotic flux. At equilibrium (incoming flux = outgoing flux), this pressure is called osmotic pressure. In plant cells, when ‘the box is filled’, the mechanical pressure of the cell wall prevents the cell from expanding further or even blowing up. - technical applications of osmosis are dialysis and water desalination. Both use artificial membranes permeable to water and small molecules, but impermeable to bigger solutes. In hemodialysis, blood is channeled through tubes immersed in hypertonic salt solution: water and small molecules transit, while bigger molecules (e.g. glucose) and blood cells are retained. In dessalination, pressure superior to the osmotic pressure is applied on the hypertonic side, thus inversing the sense of the osmotic flow. Homework: cf annexed sheet
  8. 8. 8 Lesson 7 3. active transportation of substances through biological membranes N. B. Active transportation uses up energy, but allows the cell to transport substances opposing their concentration gradient. Active transportation uses specific membrane proteins called transporters. Source: http://g11-bioa-2011- Remark : the activity of both channels and transporters can be influenced by hormones and other substances D. Transportation of voluminous material Text to be distributed Voluminous materials (cells, viral particules, macromolecules) are enclosed in an invagination of the cytoplasmic membrane, which closes up on itself and forms a ‘bubble’ called an endocytic vacuole containing the ingested matter. The phenomenon is called endocytosis. If the substance ingested is formed of solid matter (cells, pieces of cells, viral particles), it is called phagocytosis (phagocytic vacuoles or phagosomes are relatively big, with a diameter often bigger than 1 um) If the substance ingested is formed of liquid drops, it is called pinocytosis (pinocytic vesicles are small, about a 11nm in diameter) In the same way, material can be expulsed from the cell by a phenomenon called exocytosis. * phagocytosis Cf annexed sketch
  9. 9. 9 Lesson 8 Evaluation: will follow in a separate folder (I haven’t written it yet) Requirements: - Time: 8 lessons ( in my case two double lessons, 1 single lesson, 2 double lessons and another single lesson) - Material: Lesson 1: Opitcal microscopes, liver cells, slides, pincers, cover glasses Lesson 2: Opitcal microscopes, onions, waterweed, knives, scalpels, slides, pincers, cover glasses Lesson 3: pictures of different kind of bacteriae Lesson 4: container, ink, computer with internet access, handouts Lesson 5: Apple corers, potatoes, distilled water, physiological serum, concentrated salt or sugar solution, containers, rulers, microscopes, slides, cover glasses, pipettes, beef blood Lesson 6: handouts Lesson 7: handouts Lesson 8: handouts Teaching methods Lesson 1: didactic teaching, the students practice taking notes; guided practical work Lesson 2: guided practical work Lesson 3: didactic teaching Lesson 4: problem solving, didactic teaching Lesson 5: practical work, problem solving, didactic teaching Lesson 6: didactic teaching Lesson 7: didactic teaching Lesson 8: Evaluation
  10. 10. 10 Homework lesson 6 1. How many concentration gradients can you identify? Draw an arrow from high concentration to low for each solute. 5 mM K+ 142 mM Na+ 100 mM Cl- 4 mM PO4- 2. Explain what a concentration gradient is using the figure as an illustration for your points. 3. Describe what is meant by a semi-permeable membrane. Source: Peer-Led Team Learning: Anatomy and Physiology, Module 7: Cell Membranes and Transport, Page 1 – Nichole McDaniel -- Progressions, V.7, No. 3, Spring 2006 – Volume 7, Issue 3 Spring 2006 The Workshop Project Newsletter nucleus 140 mM K+ 10 mM Na+ 4 mM Cl- 75 mM PO4-
  11. 11. 11 ___active transport A. Movement of molecules down the concentration gradient ___phospholipid B.When placed in such a solution the cell swells and bursts ___fluid mosaic model C. Movement of water molecules towards salt across a semipermeable membrane. ___passive transport D. When placed in such a solution the cell remains stable ___pinocytosis E. When placed in such a solution the cell shrivels ___osmosis F. A secretory vesicle uses this method to expel its contents outside the cell ___phagocytosis G. It has a hydrophilic head and a hydrophobic tail. ___ facilitated diffusion H. A process by which the cell engulfs water (liquid) ___ simple diffusion I. A process by which the cell engulfs solid objects such as a pathogen ___ endocytosis J. The molecular arrangement of the cell membrane is described in this way. ___ exocytosis K. This type of transport requires a protein but not ATP ___ hypertonic L. This type of transport requires both a protein pump and ATP. ___ hypotonic M. Any type of transport that does not require ATP ___ isotonic N. Cholesterol is picked up by liver cells using this method. Peer-Led Team Learning: Anatomy and Physiology, Module 7: Cell Membranes and Transport, Page 1 – Nichole McDaniel -- Progressions, V.7, No. 3, Spring 2006 – Volume 7, Issue 3 Spring 2006 The Workshop Project Newsletter QCM Use the diagram to answer questions 3 and 4. 3. What happens with the water molecules? a. The water molecules will enter the cell. b. The water molecules will move out of the cell. c. The water molecules will remain where they are. 4. What happens with the sugar molecules? a. The sugar molecules will enter the cell. b. The sugar molecules will move out of the cell. c. The sugar molecules will remain where they are. 5. Through which process do sugar molecules enter or exit a cell? a. diffusion c. facilitated diffusion b. osmosis d. none of the above 6. Which process ALWAYS involves movement of materials from inside the cell to outside the cell? a. osmosis c. exocytosis b. diffusion d. endocytosis 7. A substance that moves across a cell membrane without using the cell’s energy tends to move a. toward the area where it is more concentrated. b. away from the area where it is less concentrated. c. away from the area where it is more concentrated. 8. If a solution outside a cell is more concentrated so that the cell loses water to its environment, which of the following describes the external solution? a. isotonic c. hypertonic b. hypotonic d. in equilibrium Cell Membrane Outside Cell Inside Cell = Sugar
  12. 12. 12 9. Which mechanism requires energy? a. osmosis c. active transport b. diffusion d. facilitated diffusion 10. Certain types of lymphocytes (white blood cells) in the lymph nodes ingest bacteria and debris. This function most likely occurs by a. exocytosis d. passive transport b. pinocytosis e. facilitated transport c. phagocytosis 11. Which of the following is characteristic of cell membrane? a. permeable c. semi permeable b. impermeable d. none of these 12. Which refers to a solution containing a greater concentration of solvent than the solution it is being compared with? a. isotonic c. hypertonic b. hypotonic d. equilibrium 13. Which solution contains a higher concentration of solute than the solution it is being compared with? a. isotonic c. hypertonic b. hypotonic d. equilibrium 20Movement%20of%20Matls%20thru%20the%20Cell%20Membrane.pdf