BIOL 215 Lecture 2

Similarities and Differences Between Eukaryotic and Prokaryotic Cells

Similarities

• They are both surrounded by a lipid-based plasma membrane.
• Both types of cells have metabolic cellular machinery.
• Both types use DNA to carry hereditary information.
• Both types of cells use ribosomes to synthesize proteins.

Differences

• Prokaryotes do not have a nucleus while eukaryotes do.
• Eukaryotes have membrane-bound organelles while prokaryotes do not.
• Eukaryotic cells are much bigger in size than prokaryotic cells.

Cell Size and the Surface Area to Volume Ratio

• Why is cell size limited?
    * Resource availability
    * Surface area to volume ratio
      * This is important because a cell with a low surface area to volume ratio cannot properly exchange substances between the intracellular and extracellular environments.

Strategies to Overcome the Surface Area to Volume Ratio Limitations

• Division of cells
• Halting growth by entering the G0 phase of the cell cycle
• Folding the membrane to increase surface area
    * This can occur in both the plasma membrane and membranes around the organelles
• Creating cells that are thin and long
• Using active transport
• Multicellularity

Epithelial vs Endothelial Cells

• $Epithelial cells$: cells that line the outer or inner surfaces of organs or tissues
• $Endothelial cells$: cells that line areas of the cardiovascular system, specifically blood vessels

Cell Fractionation

• Cells first have to be lysed
    * $Lyse$: to break open a cell by exposure to chemicals, enzymes, or sound waves
• Then, homogenization needs to occur
    * $Homogenization$: blending together the subcellular contents
• Finally, these parts need to undergo centrifugation
    * $Centrifugation$: using the centrifugal force to separate different parts of the cell based on density and size
      * The biggest and densest parts of the cell go to the bottom of the centrifuge tube.