Intro to Metabolism
Learning Outcomes Explain laws governing energy and energy transfers. Describe enzymes and how they work. Explain what is meant by selectively permeable. Explain the differences between diffusion, facilitated diffusion, and active transport. Explain osmosis and be able to predict the net movement of H 2 O molecules under various conditions Describe endocytosis (e.g., phagocytosis) and exocytosis
Life Needs Energy The Rules (Laws of Thermodynamics) 1) energy can not be created or destroyed, but it can be changed from one form to another 2) when energy is changed from one form to another there is always some loss of usable energy (i.e., entropy increases).
Entropy Increases
Life Needs Energy Potential Energy --- stored energy Kinetic energy energy of motion In living systems, energy is stored in the form of chemical bonds
Life Needs Energy In living systems, energy is stored in the form of chemical bonds Reactants Products 2H 2 (hydrogen ) + O 2 (oxygen ) 2H 2 O (water ) 4 hydrogen atoms + 2 oxygen atoms 4 hydrogen atoms + 2 oxygen atoms
Energy Transformations Reactants Potential energy Energy Products Amount of energy released When chemical bonds in molecules are broken down, energy is released.
Energy Transformations Products Potential energy Reactants Energy Amount of energy required To build complex molecules energy input is required.
Enzymes Facilitate Chemical Reactions enzyme binding to substrates chemical rxn completed product released
Enzymes Facilitate Chemical Reactions Transition state Free energy Reactants Activation energy without enzyme Activation energy with enzyme Products Time
Metabolic Pathways Require Enzymes Metabolism is the sum of all chemical reactions occurring in a living system at any given time. Metabolic pathways are specific subsets of chemical reactions. Most metabolic pathways are similar in all organisms. We will look at two important metabolic pathways photosynthesis and respiration
Metabolic Pathways Require Enzymes A series of chemical reactions form a metabolic pathway. X Each reaction in the series is catalyzed by a specific enzyme. The end product of a pathway can inhibit the enzyme that starts the pathway.
Where in real life do we see enzyme inhibitors? Many of the Drugs used in medicine are enzyme inhibitors Example 1) Aspirin blocks an enzyme called cyclo-oxygenase that makes pro-inflammatory molecules that activate inflammation responses by the immune system
Where in real life do we see enzyme inhibitors? Example 2) Lipitor Lipitor and other statins work by blocking an enzyme called HMG-CoA Reductase that is required for cholesterol synthesis CHOLESTEROL
The Lipid Bilayer is a Barrier Phospholipid Bilayers are selectively permeable Non-polar or hydrophobic molecules can pass through Polar or hydrophilic molecules can not
SO - How do we get stuff in and out of the cell? IN diffusion OUT - exocytosis facilitated diffusion active transport endocytosis phagocytosis
Diffusion: Molecules move from high concentration to low concentration.
Diffusion: Molecules move from high concentration to low concentration.
Osmosis Osmosis is the diffusion of H 2 O across a semi-permeable membrane Movement of H 2 O depends on what is dissolved in the H 2 O Dissolved substance = solute Flow of H 2 O
Osmosis Osmosis
Facilitated Diffusion Molecules move down their concentration gradient no energy input required. Extracellular Fluid glucose Cytoplasm
Facilitated Diffusion
Active Transport Energy is required to move molecules against their concentration gradient Extracellular Fluid Cytoplasm
Active Transport
Endocytosis Part of the plasma membrane encapsulates material outside the cell.
Phagocytosis similar to endocytosis, but for uptake of LARGE particles.
Exocytosis Vesicles from the Golgi apparatus fuse with the plasma membrane and release material to the outside of the cell.