Types of Cell Prokaryotes  single-celled organisms  Lack any detectable internal compartments  Escherichia coli – the most thoroughly studied organism on earth (part of the intestinal flora) Eukaryotes  Infinitely more genetic information  Contain multiple membrane bodies known as organelles

Difference between prokaryotes and eukaryotes Prokaryotes o No cytoskeleton o Less DNA content o Do not contain membrane-bound organelles o Smaller Eukaryotes o Presence of cytoskeleton o Hundreds to thousand times more DNA o Presence of organelles o About 5-10 times larger

ORGANELLES AND THEIR MAJOR FUNCTIONS Nucleus Nucleus Mitochondrion Mitochondrion Golgi Apparatus Golgi Apparatus Endoplasmic Reticulum Endoplasmic Reticulum Lysosomes Lysosomes Stores DNA; involved in the expression of genetic information and ribosome assembly Stores DNA; involved in the expression of genetic information and ribosome assembly Oxidation of fuel; energy production; powerhouse of the cell Oxidation of fuel; energy production; powerhouse of the cell Modification and transport of proteins and lipids from the endoplasmic reticulum; production of lysosomes Modification and transport of proteins and lipids from the endoplasmic reticulum; production of lysosomes Processing, synthesis, packaging and transport of its products (proteins and lipids) Processing, synthesis, packaging and transport of its products (proteins and lipids) Intracellular digestion of materials brought into cells, breakdown and recycling of cellular components of damaged parts of the cell Intracellular digestion of materials brought into cells, breakdown and recycling of cellular components of damaged parts of the cell

Methods of Material Transfer Diffusion – the movement of solute particles from a region of greater concentration to one of lower concentration Osmosis – the passage of solvent molecules from a region of lower solute concentration to one of greater solute concentration Dialysis – the separation of colloidal particles from those of true solution by means of a semi- permeable membrane Active transport – the movement of material against a concentration gradients, and therefore requires enzymes and energy

Types of Solution based on Tonicity Isotonic – two solutions with the same solute concentration; solution with a concentration equal to the inside of the cell (ex. 0.9% saline is isotonic with blood, 5.5% glucose solution is isotonic with body fluids Isotonic – two solutions with the same solute concentration; solution with a concentration equal to the inside of the cell (ex. 0.9% saline is isotonic with blood, 5.5% glucose solution is isotonic with body fluids Hypotonic – lower concentration than that inside the cell; cause hemolysis (cell bursting) Hypotonic – lower concentration than that inside the cell; cause hemolysis (cell bursting) Hypertonic – greater concentration than that inside the cell; cause cell shrinking Hypertonic – greater concentration than that inside the cell; cause cell shrinking