Cells

• Cells + What it means to be alive

  • all living things are made of cells
  • Movement - capable of individual movement
  • Respiration
  • Sensitivity to stimuli
  • Growth
  • Reproductive capacity
  • Excretion
  • Equilibrium -homeostasis
  • Nutrition
  • Prokaryotic and Eukaryotic

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• Eukaryotes

  • all multi-cellular organisms are eukaryotic, but eukaryotic cells may also be unicellular
  • membrane-bound nucleus, membrane-bound and non-membrane-bound organelles
  • larger than prokaryotes, more complex
  • linear chromosomes, in nucleus
  • plant cells, animal cells, fungal cells, protists
• Prokaryotes

  • usually unicellular
  • do not have a membrane-bound nucleus, or any membrane-bound organelles
  • smaller than eukaryotes, basic cells with very little cellular organisation
  • their DNA, ribosomes and enzymes are free-floating in cell cytoplasm
  • 1 circular chromosome known as the nucleoid
  • plasmids, ribosomes, cytoplasm (where genetic DNA is held)
  • tends to have flagella to propel itself, also always have a cell envelope with a cell membrane and cell wall (diff to plants)
  • bacteria, archaea
• Endosymbiosis

  • an endosymbiont is a cell that lives inside another cell with mutual benefit
  • eukaryotic cells are believed to have evolved from early prokaryotes that were engulfed by phagocytosis
  • the engulfed prokaryotic cell remained undigested as it contributed new functionality to the engulfing cell
  • over time, the engulfed cell lost some of its independent utility and become a supplemental organelle
  • EVIDENCE: mitochondria and chloroplast
  • have their own circular DNA
  • small in size
  • have a double outer membrane
  • divide by binary fission
• Plant Cell

  • eukaryotic
  • nucleus, mitochondria
  • has a cellulose cell wall
  • plasma membrane
  • large vacuole
  • chloroplast
  • ribosomes
  • golgi apparatus
  • endoplasmic reticulum
• Animal Cell

  • eukaryotic
  • nucleus, mitochondria
  • no cell wall
  • plasma membrane
  • centrioles
  • ribosomes
  • golgi apparatus
  • endoplasmic reticulum
• Nucleus


  Double membrane. Its role is to protect and confine the genetic information (DNA) of the cell. Inside is the nucleolus which is the site of ribosome production.

  FOUND IN: eukaryotes, Animal + plant cell
• Ribosome


  Not membrane-bound. Its role is to assemble building blocks to make proteins

  FOUND IN: eukaryotes, Animal + plant cell
• Rough ER


  Membrane bound. a chain of flattened sacs coated with ribosomes. Synthesises and modifies proteins.

  FOUND IN: eukaryotes, Animal + plant cell
• Smooth ER


  Membrane bound. a chain of flattened sacs not coated with ribosomes. responsible for the production of lipids in a cell

  FOUND IN: eukaryotes, Animal + plant cell
• Golgi Apparatus


  Membround bound. stacked flattened sacs that are sites of protein sorting, packaging, and modification for use in the cell or expert. vesicles often fuse or bud off from the golgi apparatus

  FOUND IN: eukaryotes, Animal + plant cell
• Mitochondria


  Membrane bound. site of cellular aerobic respiration which produces energy in the form of ATP. this is required to power cellular processes. contains own circular DNA and ribosomes

  FOUND IN: eukaryotes, Animal + plant cell
• Cytoskeleton


  Not membrane-bound. large network of protein filaments that start at the nucleus and reach out to the plasma membrane. critical for maintaining shape and transporting vesicles

  FOUND IN: eukaryotes, Animal + plant cell + prokaryotes
• Lysosome


  Membrane bound. breaks down cell waste and toxins. contains digestive enzymes. bigger than ribosomes

  FOUND IN: eukaryotes, Animal cell
• Vacuole


  Membrane bound sac used for water and solute storage. Plays a role in maintaining plant cell structure.

  FOUND IN: eukaryotes, (small and temp) Animal + (large and perm) plant cell + prokaryotes
• Cell Wall


  Not membrane bound. sturdy barrier outside the plasma membrane that provides strength and structure to plant, bacterial and fungal cells.

  FOUND IN: eukaryotes, Plant cell + prokaryotes (diff structure)
• Chloroplast


  Double membrane bound. contains flattened, fluid-filled sacs that are the site of photosynthesis. also has its own circular DNA and ribosomes

  FOUND IN: eukaryotes, plant cell
• Plasma membrane


  selectively permeable barrier between intracellular and extracellular environments. made with phospholipid bilayer

  FOUND IN: eukaryotes, Animal + plant cell, + prokaryotes
• Vesicle


  Small, membrane-bound sac that transports substances into or outside the cell. or store substances within a cell.

  FOUND IN: eukaryotes, Animal + plant cell
• Surface Area to Volume Ratio

  • the smaller the size, they quicker they get things diffused into them. like oxygen in, carbon dioxide out. water in, etc etc.
  • the cells which are consistently transporting stuff, can get rid of the things they need, and take in the things they need, quicker and more efficiently.
  • flat, elongated shapes with fingerlike projections (villi) increases SA:V
  • larger the cell, the smaller the SA:V is (bad)