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1. Introduction To Cells


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1. Introduction To Cells

  1. 1. Define the following word: Cell
  2. 2. 1.1 Animal Cells <ul><li>Today’s Learning Objectives: </li></ul><ul><li>State what cells are </li></ul><ul><li>Distinguish between unicellular and </li></ul><ul><li>multicellular organisms </li></ul><ul><li>Name three structures in animal cells </li></ul><ul><li>Labelled diagram of animal cell </li></ul><ul><li>Main features and function of animal cell </li></ul><ul><li>structures </li></ul><ul><li>The need for using stains when looking at </li></ul><ul><li>cells with a microscope </li></ul>
  3. 3. Typical Animal Cell Cytoplasm Nucleus Cell membrane
  4. 4. Unicellular Amoeba <ul><li>Unicellular animal found in pools </li></ul><ul><li>and puddles </li></ul><ul><li>-Nucleus contains all genetic information </li></ul><ul><li>-Numerous ‘feet’ extensions (pseudopodia) </li></ul><ul><li>which allow movement, and catch food </li></ul>
  5. 5. Cells forming tissues Bone cells Nerve cells Cardiac muscle cells
  6. 6. Looking at Animal Cells <ul><li>Examine prepared slides of animal cells using the procedure outlined in the booklet. </li></ul><ul><li>Draw an accurate biological drawing of a few cells. </li></ul><ul><li>Prepare and examine a slide of your own cheek cells. </li></ul><ul><li>Draw an accurate biological drawing of a few of your cells. </li></ul>
  7. 7. 1.2 Plant Cells <ul><li>Today’s Learning Objectives: </li></ul><ul><li>Name six structures present in plant cells </li></ul><ul><li>Draw a plant cell with these structures </li></ul><ul><li>labelled </li></ul><ul><li>Describe the features and functions of </li></ul><ul><li>these structures </li></ul><ul><li>Name a stain used to examine plant cells </li></ul><ul><li>by microscope </li></ul>
  8. 8. Typical Plant Cell Cytoplasm Nucleus Cell membrane Sap vacuole Cell Wall Chloroplast
  9. 9. Cell Structure and Function Contains a green chemical called chlorophyll. This green chemical absorbs sunlight to carry out photosynthesis to make food Chloroplast Controls the water content of the plant cell Sap Vacuole Rigid firm coating around the plant cell. It helps to keep the cell shape Cell wall Controls substances that enter and exit the cell, e.g. oxygen, carbon dioxide and food Membrane Jelly like fluid which is the site of chemical reactions in the cell Cytoplasm Control centre of the cell. Contains information which controls everything that goes on in the cell Nucleus Function Structure
  10. 10. Looking at Plant Cells Pond weed cells Plant leaf cells packed with chloroplasts
  11. 11. 1.3 Cell Variety <ul><li>Today’s Learning Objectives: </li></ul><ul><li>Name three main types of cell </li></ul><ul><li>State similarities and differences </li></ul><ul><li>between animal and plant cells </li></ul><ul><li>Define the term microbe </li></ul><ul><li>Calculate microbial cell reproduction rates </li></ul><ul><li>Give three examples of microbial cells </li></ul><ul><li>State the power of microscope needed to </li></ul><ul><li>see bacterial cells </li></ul>
  12. 12. <ul><li>Microbes are microscopic unicellular organisms </li></ul><ul><li>Some can be harmful and cause disease </li></ul><ul><li>(bacteria, viruses and parasites </li></ul><ul><li>Others can be useful and used to make products </li></ul><ul><li>in the biotechnology industries: </li></ul><ul><li>-Yeast: brewing, breadmaking </li></ul><ul><li>-Fungi: Antibiotics </li></ul><ul><li>-Bacteria: cheese and yoghurt </li></ul><ul><li>production </li></ul>
  13. 13. Paramecium <ul><li>Unicellular animals found in fresh water pools </li></ul><ul><li>Feed on bacteria </li></ul><ul><li>Covered in cilia which beat in a wave for movement </li></ul>Cell division Tiny hairs (cilia)
  14. 14. Vorticella <ul><li>Bell shaped heads have tiny hairs (cilia) which waft food towards them </li></ul><ul><li>- Cilia are also used for movement </li></ul><ul><li>Each head is attached to a stalk which anchors to a surface </li></ul><ul><li>-When disturbed it can contract the stalk for protection </li></ul>
  15. 15. Pleurococcus <ul><li>Forms a powdery, green covering on </li></ul><ul><li>the bark of trees </li></ul><ul><li>Very common single-celled algae </li></ul><ul><li>Can withstand drought and is able to </li></ul><ul><li>get water directly from the air </li></ul><ul><li>divides rapidly in good, moist </li></ul><ul><li>conditions and spreads quickly </li></ul>
  16. 16. Amoeba <ul><li>Unicellular animal found in pools </li></ul><ul><li>and puddles </li></ul><ul><li>-Nucleus contains all genetic information </li></ul><ul><li>-Numerous ‘feet’ extensions (pseudopodia) which allow movement, and catch food </li></ul>An amoeba on a wash cloth These little things are bacteria!
  17. 17. Yeast - Unicellular fungus - Cell is dividing - Ferment sugars (used in brewing and bread making) These circles are formed when the cell divides. The new cell ‘ buds off’ and leaves a scar.
  18. 18. 1.4 Cells and Biotechnology <ul><li>Today’s Learning Objectives: </li></ul><ul><li>Describe the fermentation process in yeast </li></ul><ul><li>Name three industries in which yeast is used </li></ul><ul><li>State the source of sugar in each of these </li></ul><ul><li>industries </li></ul><ul><li>Describe how antibiotics are produced </li></ul><ul><li>Give a use for antibiotics </li></ul><ul><li>Name the microbe type used in yoghurt </li></ul><ul><li>making </li></ul><ul><li>Write the word equation for lactic acid </li></ul><ul><li>production by yoghurt bacteria </li></ul>
  19. 19. Sugar Alcohol + Carbon Dioxide Fermentation by Yeast <ul><li>Biotechnology involves putting cells </li></ul><ul><li>to work </li></ul><ul><li>Fermentation is a biological process in which microbes (e.g. yeast cells), convert sugar into alcohol and carbon dioxide. </li></ul>
  20. 20. The discovery of Sir Alexander Fleming! ANTIBIOTICS Fungus Bacteria
  21. 21. <ul><li>Antibiotics are antibacterial (bacteria killing) </li></ul><ul><li>chemicals, produced by fungus </li></ul><ul><li>Obtained industrially by growing yeast in large </li></ul><ul><li>fermentation vessels, provided with food. Liquid </li></ul><ul><li>produced is filtered out and antibiotics purified </li></ul><ul><li>Antibiotics only work against bacteria, so not </li></ul><ul><li>used against viruses such as the cold or flu </li></ul><ul><li>Problems arise when bacteria built up resistance </li></ul><ul><li>to antibiotics and they no longer kill them </li></ul><ul><li>e.g. hospital ‘superbugs’ that are always in the news </li></ul><ul><li>MRSA= Methicillin Resistant Staphylococcus Aureus </li></ul>
  22. 22. Yoghurt Making Lactose Lactic acid Bacteria Sugar found in milk Reduces pH of milk causing it to clot (thicken) Bacteria convert lactose into lactic acid
  23. 23. What substances need to get into and out of cells? How do they do this?
  24. 24. 1.5 Cells and Diffusion <ul><li>Today’s Learning Objectives: </li></ul><ul><li>Name the method by which substances move in </li></ul><ul><li>and out of cells </li></ul><ul><li>Define diffusion </li></ul><ul><li>State when diffusion will stop </li></ul><ul><li>From diagrams, predict the direction of </li></ul><ul><li>movement of substances by diffusion </li></ul><ul><li>State which substances enter and leave living </li></ul><ul><li>cells by diffusion </li></ul><ul><li>Give one reason why diffusion is important to </li></ul><ul><li>whole organisms </li></ul>
  25. 25. <ul><li>Substances have to pass into and out of cells </li></ul><ul><li>These movements most commonly occur by diffusion </li></ul>Diffusion is the movement of molecules from an area of HIGH concentration to an area of LOW concentration until they are EVENLY spread
  26. 26. Animation of diffusion Click on address to view
  27. 27. Food molecules Oxygen molecules Carbon dioxide molecules Diffusion in or out of a living cell
  28. 28. 1.6 Cells and Osmosis <ul><li>Today’s Learning Objectives: </li></ul><ul><li>Name the method by which water passes in </li></ul><ul><li>and out of cells </li></ul><ul><li>Explain what a selectively permeable membrane is </li></ul><ul><li>State what osmosis is using the terms </li></ul><ul><li>selectively permeable membrane and concentration </li></ul><ul><li>gradient </li></ul><ul><li>Identify water concentration gradients when </li></ul><ul><li>given solute concentrations </li></ul><ul><li>Predict the direction of water movement between </li></ul><ul><li>two solutions of know concentration </li></ul><ul><li>Describe and predict a visking tubing experiment </li></ul>
  29. 29. OSMOSIS is the special diffusion of WATER from a HIGH WATER concentration to a LOW WATER concentration through a SELECTIVELY PERMEABLE MEMBRANE A membrane which is selectively permeable allows certain molecules to pass through but not others.
  30. 30. Membrane fully permeable to small molecules e.g. water Membrane slowly permeable to larger molecules e.g. sugar Membrane is not permeable to huge molecules e.g. starch Selectively permeable membrane Nucleus Cytoplasm
  31. 31. Concentration Gradient 99% water 1% sugar 95% water 5% sugar Higher concentration of water Lower concentration of water
  32. 32. Water moves down a concentration gradient by OSMOSIS from high to low concentration Lower concentration of water Higher concentration of water Water molecule Sugar molecule Selectively permeable membrane
  33. 33. Osmosis Animation Click on address to view
  34. 34. 1.7 Osmotic Effects on Cells <ul><li>Today’s Learning Objectives: </li></ul><ul><li>Explain why osmotic effects are different on </li></ul><ul><li>plant and animal cells </li></ul><ul><li>State the meaning of isotonic, hypertonic and </li></ul><ul><li>hypotonic </li></ul><ul><li>Describe the effect on plant cells of emmersion </li></ul><ul><li>in different solutions </li></ul><ul><li>State the meanings of flaccid, turgid, plasmolysed </li></ul><ul><li>Predict the effect of different solutions on plant cells and label diagrams </li></ul><ul><li>Recognise and label plant cells in various </li></ul><ul><li>conditions </li></ul><ul><li>Describe and predict the effect of animal cells on emmersion in different solutions </li></ul>
  35. 35. Water Concentrations A dilute sugar solution has a high water concentration A concentrated solutions has a low water concentration Water moves in or out of a cell depending on whether the water concentration outside the cell is higher or lower than the water concentration inside the cell
  36. 36. A HYPOTONIC solution has a higher water concentration than inside the cell A HYPERTONIC solution has a lower water concentration than inside the cell An ISOTONIC solution has a water concentration equal to the water concentration in the cell