Biology Summery (F211)

• 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

• 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

• 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

• 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

• 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 

• 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

• 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

• 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

• 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 

• 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 

• 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