the plant cell

• spontaneous generation theory says that living organisms can originate from inanimate objects
• fransisco redi observed that maggots arise from flies
• john needham observed that bacteria originated from meat
• lazaro spallanzani observed that air carried germs to flask
• theodore schwann concluded that no growth after air that passes through glass is heated
• schroder and dusch - microorganisms from environment was trapped by cotton
• pasteur disproved spontaneous generation theory and his experiment led to germ theory of disease
• robert hooke coined the term cell
• antoine van leeuwenhoek observed living cells
• robert brown coined the term nucleus
• matthias schleiden - all plants are made by cells
• theodore schwann - all animals are made by cells
• rudolph virchow - omnis cellula e cellula (all cells are from other pre-existing cells)
• cells can efficiently exchange materials because theyre small
• surface area relative to volume decreases as cell size increases
• cell theory:

  1. all living things are composed of 1+ cells
  2. cells are the basic units of structure + function of organism
  3. cells come from pre-existing cells
• DNA is located in nonmembrane bound nucleoid region(prokaryotic)/membrane bound nucleus (eukaryotic)
• plasma membrane functions as a selective barrier for import and export materials
• cytoplasm consists of cytosol and organelles and other particulates suspended in it

  • contains hereditary material
  • surrounded by cell membrane
• steps of symbiogenesis

  1. prokaryotic cells grow and develop
  2. infoldings pinch off forming endomembrane system and enclosing nucleoid → eukaryote
  3. aerobic protobacteria becomes entosymbiont
  4. proteobacteria becomes mitochondria
  5. another endosymbiont-like cyonobacteria become chloroplasts
• similarities of mitochondria and chloroplasts

  1. similar to bacteria in size and structure
  2. bounded by double membrane
  3. contains circular DNA and divides by splitting
  4. has ribosomes and produces proteins like prokaryotes
  5. have RNA base sequences suggesting prokaryotic origin
• eukaryotic cells possess a cytoskeleton for support and to maintain cellular structure
• types of plastids

  • chloroplast - does photosynthesis; green
  • leucoplats - storage of starch/oil; colourless
  • chromoplast - produce and stores pigments; pigmented
• endoplastic reticulum is the site of enzymatic activity and synthesizes membranes such as nuclear envelope and lipids
• rough ER has ribosomes embedded on the surface while smooth ER lacks ribosomes
• golgi apparatus modifies, packages, and sorts proteins that will be secreted and sent to plasma membrane/other organelles
• vacuole cointains solution of:

  • salts
  • ions
  • pigments
  • waste materials
• cytoskeleton maintains cell shape and is involved in cellular movement
• cellulose is the most abundant organic polymer on earth
• plasmodesmata allows communication between cells