more flash cards

• millimeters (mm)


  1/10 of a centimeter
• micrometres (μm)


  1/10000 of a centimeter
• nanometres (nm)


  1/10000000 of a centimeter
• Calculating actual size of specimen in microscopy

  Equation
• Magnification


  The number of times an image is larger than the original
• Resolution


  The smallest distance between 2 points where the 2 points can still be distinguished
• Types of microscope


  • Optical microscopes
  • Electron microscopes
• Electron microscopes have better resolution than optical microscopes
• Nucleus


  • Surrounded by nuclear envelope (double membrane)
  • Contains genetic material (chromatin)
  • Contains nucleolus that synthesises ribosomes
• Roles of the nucleus

  • Store genetic material (DNA)
  • Synthesise ribosomes
  • Regulate production of messenger RNA for protein synthesis
• Functions of the cell surface membrane

  • Encloses cell to form boundary between cytoplasm and outside environment
  • Controls movement of substances in and out of cell (selectively permeable)
  • Contains proteins and molecules for cell signalling and recognition
• Structure of rough endoplasmic reticulum (RER)

  • Contains ribosomes on surface for protein synthesis
  • Membranes spread extensively for transport of proteins
• Smooth endoplasmic reticulum (SER)

  Does not have ribosomes on outer surface
• Function of smooth endoplasmic reticulum (SER)

  Synthesises and transports lipids
• Structure of mitochondria


  • Oval-shaped
  • Double membrane bound, inner membrane folded into cristae
  • Contains jelly-like fluid called matrix
  • Contains circular DNA and 70S ribosomes
• Process that occurs in mitochondria

  Aerobic respiration, which produces ATP
• Function of Golgi body


  • Modification and packaging of protein and lipids for exocytosis or distribution within the cell
  • Produces lysosomes
• Lysosomes


  Vesicles from Golgi body that contain digestive enzymes
• Functions of lysosomes


  • Hydrolyse ingested pathogens in phagocytes
  • Digest old, worn out organelles in cells
  • Break down cells after cell death
• Types of ribosomes


  • 80S ribosomes in eukaryotic cells (cytoplasm and RER)
  • 70S ribosomes in prokaryotic cells, chloroplasts and mitochondria
• Structure of ribosomes


  • Contain two subunits, each made up of ribosomal RNA and protein
• Function of ribosomes


  Protein synthesis
• Functions of centrioles and microtubules

  • Centrioles replicate during interphase and organise microtubules during mitosis
  • Microtubules compose cytoskeleton to give structure and allow transport within cell
• Cilium


  Hair-like structure that projects from a cell, may be motile or non-motile
• Cilia play a role in the respiratory system
• Ribosomes


  Function: Protein synthesis
• Centrioles


  Function: Replicate during interphase and organise microtubules during mitosis
• Microtubules


  Function: Compose the cytoskeleton to give structure and allow transport within the cell
• Cilium


  A hair-like structure that projects from a cell, may be motile or non-motile
• Cilia in respiratory system


  Waft mucus and pathogens or foreign material upwards and out of the lungs
• Microvilli


  Small protrusions of the cell membrane that increase the surface area to aid exchange of substances
• Chloroplasts


  • Have a double membrane and contain stroma, thylakoids arranged into grana, 70S ribosomes, and circular DNA
• Function of chloroplasts


  Photosynthesis, producing glucose, oxygen and some ATP
• Eukaryotic cells that contain a cell wall

  • Plant cells
  • Algal cells
  • Fungal cells
• Functions of plant cell wall


  • Provides mechanical strength
  • Protects cell from osmotic lysis
  • Can regulate water movement
• Cells that contain plasmodesmata

  Plant and algal cells
• Functions of plasmodesmata


  Allow undisrupted flow of materials via the symplastic route, and efficient exchange of substances between cells without crossing the cell wall and membrane
• Functions of the large permanent vacuole

  • Stores cell sap
  • Maintains turgor pressure
  • Acts as a temporary food store
• Organelles and cell structures present in plant cells but not animal cells


  • Cell wall
  • Chloroplasts
  • Large permanent vacuole and tonoplast
  • Plasmodesmata
• Bacterial cells are prokaryotic cells