Energy Energy (E)– the ability to perform work Potential E (E P )- stored energy Kinetic E (E K )– energy of motion Heat – kinetic energy of molecules

Endergonic Reactions Endergonic – energy inside Reactions that take in energy and store it in chemical bonds Photosynthesis

Exergonic Reactions Exergonic – Energy outside Reactions that release stored chemical energy Cellular Respiration

Energy of Activation E A – the amount of energy required to start the reaction Lit fuse on a firecracker Spark in an engine

Enzymes : Protein Catalysts Enzymes – proteins that speed up chemical reactions, each enzyme promotes a specific reaction Substrate – the molecule that is targeted by the enzyme

Enzyme : Substrate Sucrase : sucrose Lactase : lactose Helicase : DNA helix

Competitive inhibition – the inhibitor blocks the active site, preventing the enzyme from accepting any substrate molecules

Noncompetitive inhibition – the inhibitor changes the shape of the active site, preventing the enzyme from accepting any substrate molecules

Diffusion Diffusion- the natural tendency of molecules to move from areas of high to low concentration

Passive transport Transport that doesn’t use cellular energy

Osmosis : The diffusion of Water Osmosis occurs when the solute is not able to move across the membrane. In order to reach equilibrium, water moves across the membrane. Water concentration, not solute concentration determines direction of movement.

Hyper-, Hypo-, or Isotonic The concentration of solutes in a solution are compared with those inside the cell. Hypertonic – a solution whose concentration of solutes is higher than that in the cell Hypotonic- a solution whose solute concentration is lower than that in the cell Isotonic – a solution whose concentration os solutes is equal to that in the cell

Active Transport Active transport requires energy to move a substance through a cell membrane.

Exocytosis – “Outside the cell” bulk movement of materials out of the cell

Endocytosis – “Inside the cell” bulk movement of materials into the cell

Phagocytosis, Pinocytosis, Receptor-mediated endocytosis