Biology Summery (F211)

Observing Cell Structure

  • Two types of microscope:  
    • Light -  ×1500 low resolution                       
    • Electron - ×500 000 high resolution
  • Resolution - how well objects can be seen between two points
  • Light microscopes need stains
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Cell Structure and Function

  • Organelles: 
    • Nucleus 
    • Nucleolus - makes ribosomes
    • Mitochondria - makes ATP for cell activity
    • Lyosomes - contains enzymes
    • Ribosomes - make proteins
    • RER - transports protien to Golgi
    • Golgi Apparatus - packages and secretes protiens
    • Chloroplast - (plant only) site for photosynthesis
    • Centrioles - (animal only) aid cell division
    • Cilia/Flagella - beat to produce cell movement
  • Eukaryotic cells have nucleus and membrane bound organelles
  • Prokaryotes have naked DNA and no membranes
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Cell Membranes

  • The fluid mosaic model is a phospholipid bilayer with scattered proteins 
  • Phospholipid bilayer is a transport (partially permiable) and cell recognition/signalling
  • Passive transport = diffusion/ facilitated diffusion doesn't use energy, against conc. gradient 
  • Osmosis = diffusion of water from high potential to low potential across a membrane
  • Endocytosis = bulk movement of fluid/particles into cells
  • Exocytosis = movement outside of cells
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The Cell Cycle

  • When a cell divides, it copies and checks genetic information
  • Cells can either continue a cell cycle or differentiate
  • Main Stages:

Prophase - chromosomes thicken

Metaphase - chromosomes line up at equator

Anaphase - chromatids separate

Telophase - each chromatid forms a new nucleus

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Cell Organisation

  • Daughter cells produced in mitosis are identical
  • Meiosis aren't identical
  • Some mitosis produces stem cells, cann differentiate into specialised cells
  • Organs are a group of specialised cells working together to perform a specific function 
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Gaseous Exchange

  • Alveolus wall is only 1 cell thick - efficent exchange surface
    • Moist and folded for large surface area
  • Alveolus is rich with capillaries
  • Intercostal muscles move lungs making air flow in/out
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Lung Structure and Function

  • Trachea and bronchi have cartilage rings which support for air flow
  • Smooth muscles contract and narrow bronchi and bronchioles 
  • Goblet cells in trachea lining secretes mucus trapping pollen and bacteria
  • Ciliated epithelial cells  waft mucus up/out of throat
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Animal Transport Systems

  • Large organisisms have small SA:V (Surface Area to Volume Ratio)
    • large distance for diffusion of gasses
  • Special blood systems needed
    • Single (fish) heat - gills - body - heart
    • Double (mammals) left heart - body - right heart - lungs - left heart
    • Closed Circulatory blood stays in vessels
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Heart Structure

  • Left ventricle - thicker, pumps blood to rest of the body
  • Right ventricle - thinner, pumps blood to lungs
  • Atria walls - pump blood to ventricles 
  • Cardiac cycle
    • chambers fill
    • venticles contract
    • atria contract
  • The SAN (Sino-Atrial Node) maintains beat rhythm
  • The AVN (AtrioVentricular Node) and Purkinye fibres pass beat to ventricles 
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Plant Transport - Water & Xylem

  • Water and minerals taken up by roots are carried by open tube of dead cells (xylem)
  • Water get to the xylem by the apoplast (cell wall) and symplast (cyptoplasm) pathways
  • Transpiration stream pulls water up the xylem
    • Cohesion holds water together
    • Adhesion holds them to the xylem walls 
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Plant Transport - Translocation & Phloem

  • Phloem is living tissue which carries substances, called translocation
  • Translocation occurs from where sucrose is produced (the source), to where they are used (the sink)
  • Translocation required energy
  • 2 cell types in phloem:
    • sieve tubes - tube of cells
    • companion cells - organelles that moves sucrose into sieve tubes
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