Topic 2 - Cells

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Topic 2 - Cells
2013-04-03 13:52:23

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  1. Name some examples of uni-cellular cells
    Amoeba, Chlorella, Euglena
  2. Outline cell theory
    • 1. living organisms are composed of cells
    • 2. cells are the smallest units of life
    • 3. cells come from pre-existing cells
  3. How do unicellular organisms carry out all the functions of life?
    • 1. Metabolism - chemical reactions inside the cell
    • 2. Response - react to stimuli
    • 3. Homeostasis - control conditions inside cell
    • 4. Growth - increase in size
    • 5. Reproduction - produce offspring
    • 6. Nutrition - obtain food
  4. Examine the image below
  5. What are the approximate sizes of
    1. molecules
  6. What are the relative sizes of
    2. cell membrane thickness
  7. What are the relative sizes of
  8. What are the relative sizes of
  9. What are the relative sizes of
    less than 10um
  10. What are the relative sizes of
    <100 um
  11. What calculation must you do to calculate the magnification of an image from the original specimen?
    Magnification =

    measured length of the image /measured length of the specimen
  12. Why can't cells be very large and still function?
    • As the organism gets bigger its surface area to volume ratio decreases. This then is a factor limiting cell size.
    • As the cell gets bigger the ratio decreases. If the ratio decreases the rate of exchange decreases.
  13. What is a stem cell?
    A cell that has the capacity to divide and has the ability to differentiate along different pathways.
  14. Name two therapeutic uses of stem cells
    Using cord blood for
  15. Examine the diagram below
    Grab a pencil and draw the diagram quickly and label the same.
  16. Outline 2 roles of extracellular components of eukaryotic cells
    • Plant cell wall maintains shape, prevents excessive water uptake and holds plant up
    • Animal cells secrete glycoproteins which functinos in support, adhesion and movement
    What is the function of the CELL WALL?
    Forms a protective outer layer to prevent damage from outside and stops bursting if internal pressure is too high
    What is the function of the PLASMA MEMBRANE?
    Controls entry/exit of substances - pumping some of them in by active transport
    What is the function of the CYTOPLASM?
    Contains enzymes to catalyse chemical reactions of metabolism and contains DNA in region called nucleoid
    What is the function of the PILI?
    Hair like structures projecting from cell wall. Can be used to pull two bacterial cells together.
    What is the function of the FLAGELLA?only in plant cells, not in animal cells
    Solid protein structures, projecting from cell wall which rotate and cause locomotion
    What is the function of the RIBOSOMES?
    Make proteins by translating mRNA
    What is the function of the NUCLEOID?
    Region of cytoplasm that contains naked DNA - the genetic information in the cell
  24. How do prokaryotic cells divide?
    By binary fission (asexual reproduction) daughter cells have identical genetic information as parent cell
  25. Look at the diagram below.

    What are MV? What are M? What are L? What are rER? What is the PM? What is the GA?
    • MV - microvilli - increased surface area for uptake of substances
    • M - mitochondria - for release of energy
    • L - lysosomes - clean up junk in cell
    • rER - rough endoplasmic reticulum - transports proteins
    • PM - plasma membrane - controls what goes in/out cell
    • GA - golgi apparatus - modifies proteins
  26. State 5 differences between plant and animal cells
    • 1. Cell wall - only in plant cells, not in animal cells
    • 2. Chloroplasts - only in plant cells, not in animal cells
    • 3. Polysaccharides - starch used as storage compound in plant cells and glycogen is storage compound in animal cells
    • 4. Vacuole - large and fluid filled in plant cells, not usually present in animal cells
    • 5. Shape - fixed shaped in plant cells - usually regular. Able to change shape in animal cells - usually rounded
  27. Look at the diagram below.

    State what happens in interphase
    • G1 The cell performs its normal differentiated function. Protein synthesis/ mitochondria replication/ chloroplast replication.
    • S DNA replication. At this point the mass of DNA in the cell has doubled.
    • G2 Preparation for cell division
  28. State 8 differences between prokaryotes and eukaryotes
    • Prokaryotes are less than 5um, eukaryotes are more than 10um
    • Prokaryotes are always unicellular, eukaryotes are often multi-cellular
    • Prokaryotes have no nucleus but have a naked loop of DNA (nucleoid) eukaryotes have a membrane bound nucleus with linear chromosomes bound with histones
    • Prokaryotes have no membrane bound organelles eukaryotes have membrane bound organelles
    • Prokaryotes have small ribosomes (70S) eukaryotes have large ribosomes (80S)
    • Prokaryotes have no mitochondria eukaryotes have mitochondria
    • Prokaryotes have cell division by binary fission eukaryotes have cell division by mitosis/meiosis
    • Prokaryotes' reproduction is mainly asexual, eukaryotes' reproduction is asexual or sexual
  29. What does differentiation mean?
    When cells become different cell types to perform different jobs.
  30. Examine the diagram and label
  31. List some functions of membrane proteins
    • Hormone binding sites
    • Immobilized enzymes
    • Cell adhesion
    • Cell-to-cell communication
    • Channels for passive transport
    • Pumps for active transport.
  32. What is diffusion?
    Diffusion is the passive movement of particles from a region of high concentration to a region of low concentration.
  33. What is osmosis?
    Osmosis is the passive movement of water molecules, across a partially permeable membrane, from a region of lower solute concentration to a region of higher solute concentration.
  34. What are tumours?
    They are the result of uncontrolled cell division and that these can occur in any organ ortissue.
  35. What happens in interphase of cell cycle?
    Is an active period in the life of a cell. Many metabolic reactions occur, including protein synthesis, DNA replication and an increase in the number of mitochondria and/or chloroplasts.
  36. Mitosis is used in what processes?
    • Growth
    • Embryonic development
    • Tissue repair
    • Asexual reproduction
  37. What is facilitated diffusion?
    Passive net movement of molecules from regions of high concentration to low concentration, through a selectively permeable membrane, facilitated by carrier proteins.
  38. What is a 'tissue'?
    A group of similar cells all performing the same function.
  39. Look at the diagram. What are the pink balls representing? What about the sticks that point inwards?
    • Pink balls = hydroPHILIC phophate heads
    • Sticks = hydroPHOBIC lipid tails
  40. What is the prokaryotic cell wall made from?
  41. What is passive transport?
    Passive transport involves no expenditure of energy on the part of the cell and includes diffusion, facilitated diffusion and osmosis.
  42. What is active transport?
    Active transport requires the expenditure of energy and it includes the sodium–potassium pump, endocytosis, and exocytosis.
  43. Why is the sodium-potassium pump important?
    The sodium–potassium pump is extremely important in the human body because it brings about the proper ion levels within nerves and muscles so that they can operate efficiently.
  44. What is endocytosis?
    Endocytosis occurs when a portion of the plasma membrane is pinched off to enclose macromolecules or particulates needed by the cell. This results in the formation of a vesicle inside the cell.
  45. What is exocytosis?
    Exocytosis is essentially the opposite of endocytosis. The Golgi apparatus is essential to the process of exocytosis.
  46. What is the difference of cytokinesis in plant and animal cells?
    Cytokinesis in plant cells occurs with the formation of a cell plate inside the cell and spreading out. Cytokinesis in animal cells occurs with the pinching in of the plasma membrane resulting in a cleavage furrow. It is the presence of the cell wall in plant cells but not in animal cells that brings about this difference in cytokinesis.
  47. Give a therapeutic use of stem cells.
    Restoration of insulation tissue in neurons (from May 2012 paper)
  48. What is the approx thickness of the plasma membrane of a cell?
  49. What kind of amino acids do you find on the INSIDE of transmembrane proteins (the channel)?
    • Polar amino acids
    • HELP: Polar bears (live on the 'edge' of the planet ...therefore, polar amino acids like to be on the edge of membranes - either sticking out from cell membranes - or forming channels.
  50. Where do non-polar amino acids form in membranes?
    • The are the parts of the proteins that cause them to get embedded into the membrane
    • HELP: Polar bears live on the 'edge' of the planet. Non polar bears.....opposite (inside)
    • It's silly, but might help you remember!