Cell Structure and Function Part I

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Cell Structure and Function Part I
2011-07-09 15:00:18

Biology Revision
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  1. What are the 2 main type of cells?
    Eukaryotic and Prokaryotic
  2. What is the use of a Plasma Membrane?
    Acts as a selective barrier and helps to regulate its internal composition
  3. What are the characteristics of Eukaryotes?
    • Large
    • Contain membrane-bound organelles
    • Compartmentalise portions of cytoplasm for specific functions
    • Linear DNA
  4. What are the characteristics of Prokaryotes?
    • No nucleus
    • No membrane bound organelles
    • Singular Circular DNA
  5. Conversion of units in microscopy?
    1m = 100cm = 1000mm = 106 µm = 109 nm

    • 1mm=103 µm = 106nm
    • 1µm=103nm
  6. Advantages of compartmentalization i.e cells having membrane bound organelles?
    Separates ions, enzymes and other molecules in the cytoplasm

    Separates chemical reactions, allowing each compartment to perform a different function

    Allows specialisation of cells

    Allow high concentrations of enzymes and molecules to accumulate in specific compartments (enhance efficiency of reactions)

    Each compartment has a surface for attachment of proteins for specific functions
  7. Ability of light microscope to see fine details is called the _____?
    Resolving Power
  8. Differences btwn light and electron microscope?
    • Magnification for
    • Light : 1000x
    • Live and dead specimens
    • Light

    • Magnification for Electron : 1000,000x
    • Dead specimens
    • Electrons
  9. Cell Fractionation?
    Break cells open, separate by density and size
  10. What kind of organelles sediment first?
    • From densest to least dense
    • Nucleus
    • Chloroplast
    • Mitochondria
    • Lysosomes
    • ER
    • Golgi Apparatus
    • Ribosomes
  11. Organelles that are double membrane bound?
    • Nucleus
    • Chloroplast
    • Mitochondria
  12. Organelles that are single membrane bound?
    • ER
    • Golgi Apparatus
    • Lysosome
  13. Non membrane bound organelles?
    • Ribosome
    • Centrioles
  14. Plants cell
    • Cell wall present
    • Adjacent cells joined by middle lamella
    • Plastids present
    • Single large vacuole bound by tonoplast
    • Nucleus at edge of cell
    • Centrosome present
  15. Animals Cell
    • Cell wall absent
    • Lamella absent
    • Plastids absent
    • Numerous small vacuoles
    • Nucleus centrally located
    • Centrosome with centrioles present
  16. What kind of membrane does the nuclear envelope contain?
    Double membrane separated by perinuclear space
  17. What are the pore present on nuclear envelope use for?
    Movement of substances into and out of nucleoplasm
  18. Nucleoplasm is a ___?
    collodial ground substance
  19. Nucleolus is a ___?
    Dense region in nucleoplasm not bound by membrane
  20. What does a nucleolus contain?
    DNA that codes for rRNA hence involved in synthesis of ribosomes (synthesis of ribosomal subunits 40s and 60s)
  21. Function of nucleus?
    contains most of the genetic material in the form of chromatin
  22. Chromatin is made up of?
    DNA and histones(proteins)
  23. What takes place at the nucleolus?
    rRNA and ribsomes synthesis
  24. Main role of nucleus?
    • Directs protein synthesis by syntheizing mRNA according to instructions provided by DNA
    • Control life processes by protein regulation and enzyme synthesis
    • rRNA and ribsomes synthesis
    • Contains genetic material of cell in form of chromatin
  25. Where is the chloroplast found?
    Eukaryotic Photosynthetic cells
  26. Structure of chloroplast
    • Double membrane
    • Inner membrane enclose stroma
    • Stroma - 40-80 darkly colored grana
  27. Each granum composed of
    thylakoids connected by tubes (intergrana) to adjacent grana
  28. Thylakoid membranes contain
    photosynthetic pigments, e- carriers, ATP synthase
  29. Stroma contains ?
    • 70S ribosomes
    • Enzymes essential for Calvin Cycle
    • Circular DNA
    • Starch Granules
  30. Function of chloroplast
    Site of photosynthesis
  31. Mitochondrion versus Mitochondria
    • Be very careful how many the diagram points to in exam!
    • Found in all aerobically respiring eukaryotic cells
  32. Inner membrane of mitochondria
    • is thrown into folds called cristae and project into gel-like matrix (increase surface area for proteins to attach to, increase rate of ATP synthesis)
    • Enzymes, ribosomes and DNA molecules are found here
  33. Inner surface of inner membrane
    studded with proteins which are e- carriers and elementary particles (ATP synthase)
  34. ATP synthase is?
    Protein complex that acts as both a channel and an enzyme
  35. Matrix (ground substance) contains
    • 70S ribosome
    • circular DNA
    • enzymes involve in aerobic resp
  36. Function of mitochondria
    • Synthesis of ATP by Krebs cycle and oxidative phosphorylation
    • Heat production
  37. Mitochondria and chloroplast orginate from prokaryotes
    70S ribosomes and circular DNA
  38. Endoplasmic Reticulum
    most eukaryotic animal and plant cells
  39. RER abundant in
    cells which secrete proteins (beta cells of islets of langerhans)
  40. SER abundant in
    cells that involve in lipid metabolism (liver, testes i.e. testosterone steroid)
  41. RER
    • membrane lined interconnected cavities (flattened sacs) = cisternae
    • continuous with outer membrane of nuclear envelope
  42. RER has
    ribosomes attached on outer surface of membrane
  43. Ribosomes
    site of protein synthesis
  44. The proteins synthesised are then
    passed into the lumen of the RER where they fold into their 3D configuration and modified before export or use in other parts of the cell
  45. SER consists of
    • interconnected membrane bound tubules (NO RIBOSOMES) (NOT FLATTENED SACS)
    • Continuous with RER
  46. Functions of RER
    • Post translational modifications of proteins synthesised at the ribosomes
    • Allow polypeptide to fold into 3D configuration
    • Proteins in RER transport out of cell for use
    • RER synthesise new membrane (transported to cell membrane)
  47. Functions of SER
    • Synthesise lipids (phospholipids and steroids i.e testosterone)
    • Detoxification of drugs and poisons in liver cells
    • Stores and releases calcium ions
  48. Golgi Apparatus
    • common in cells specialised for secretion
    • Several stacks of membrane-lined flat sacs (cisternae)
  49. GA consists of 2 face
    • Cis Face (receiving end)
    • Trans Face (dispatching end)
  50. Process
    Material from ER fuse with cis face and travels across cisterna by cisterna (gets modified by specific enzymes located on cisterna along the way) all the way to the trans face
  51. Vesicles remain in the cell after pinching off from GA
  52. Functions of GA
    • Modify Sort Package substances for exocytosis or use within cells
    • Synthesis of glycolipds (lipid metabolism)
    • Plant i.e synthesise cell wall polysaccharides
  53. Lysosomes
    is a bag of enzymes
  54. Lysosomes contain
    digestive enzyme (synthesised by ribsomes attached to RER) responsible for hydrolysing complex chemical compounds into simpler ones
  55. Function of Lysosomes
    • digestion of ingested particles taken in by endocytosis
    • disposal of defunt of surpus organelles
    • cell autolysis
  56. Synthesis and secretory of a secretory protein
    The protein is synthesised at the ribosomes attached to the RER and then enter the lumen of the RER. They are modified and fused with the cis face of the GA via transport vesicles. It is then modified sort and packaged into secretory vesicles and buds off from the trans face of the GA. It fuses with the plasma membrane and is secreted through exocytosis.
  57. Ribosomes can have
    both prokaryotic (70S) and eukaryotic (80S)
  58. Ribosomes are found in both
    • the surface of RER membrane
    • freely around the cytoplasm
  59. Ribosomes made up of
    ribonucleic acid (rRNA) & protein
  60. Functions of Ribosomes
    Site of protein synthesis where A.A are linked by peptide bonds
  61. Proteins synthesised by free ribosomes
    will function within cytoplasm
  62. Proteins synthesed by ribosomes bound to RER
    will be modified to form functional proteins most of the time for secretion out of cell
  63. Centrioles
    • unique to centrosome of animal cells
    • lies at right angles
  64. Centrioles
    • usually is 1 pair
    • dividing cells has 2 pair

    give rise to basal bodies of cilia and flagella found in specialised cell