Flow of energy through life Life is built on chemical reactions transforming energy from one form to another organic molecules → ATP & organic molecules sun solar energy → ATP & organic molecules
Chemical Reactions Process in which bonds between atoms are broken, and new ones are formed. This produces one or more different substances.
Chemical Equations Reactants: The starting materials for a chemical reaction. Products: The substances that form after the reaction. Follow a specific format Reactants Products NaCl Na + + Cl -
Metabolism All of the chemical reactions that occur within an organism.
Metabolism Chemical reactions of life Bond must form between molecules Occurs through dehydration synthesis Dehydration synthesis: A chemical reaction that builds up molecules by losing water molecules. Anabolic reactions – Building up molecules from smaller units - Requires an input of energy That’s why they’re called anabolic steroids!
Metabolism Bonds also must break between molecules Occurs through hydrolysis Hydrolysis: chemical reaction that breaks down molecules by adding water molecules e.g. starch into glucose Digestion Catabolic reactions – Breaking down of molecules into smaller units
Chemical reactions & energy Some chemical reactions release energy exergonic Some chemical reactions require input of energy endergonic digesting molecules= LESS organization= lower energy state building molecules= MORE organization= higher energy state
Energy is needed to start a chemical reaction ENERGY Activation Energy: The energy needed to start a chemical reaction.
Enzymes help reactions occur Enzymes: substances that increase the speed of chemical reactions. http://www.youtube.com/watch?v=XT Um-75-PL4http://www.youtube.com/watch?v=XT Um-75-PL4
Enzymes : are Proteins are Catalysts are in YOUR cells catalyzing reactions RIGHT NOW Help you maintain homeostasis Are specifically shaped by type Work on substrates Substrate: substance upon which enzymes work Have active sites (part the substrate fits into)
Some common enzymes: Amylase Catalase Sucrase DNA Polymerase Lipase Protease
Naming conventions Enzymes named for reaction they catalyze sucrase breaks down sucrose proteases break down proteins lipases break down lipids DNA polymerase builds DNA adds nucleotides to DNA strand pepsin breaks down proteins (polypeptides)
How does an enzyme work? Step 1: Enzyme attaches to its specific substrate (sucrase attaches with sucrose) Step 2: At the active site, the enzyme and the substrate interact in a way that reduces activation energy of the reaction Step 3: The reaction is complete when products form. The enzyme is now free and goes an acts on a new substrate.
Lock and Key model Simplistic model of enzyme action substrate fits into 3-D structure of enzyme’ active site H bonds between substrate & enzyme like “key fits into lock”
Some things can make enzymes work FASTER or NOT AT ALL Temperature: Enzymes work at optimal temperatures. If the temperature is too high or too low, it may change the shape of the enzyme so it won’t work. pH: Values outside of the preferred range of enzymes may cause bonds to break and then the enzyme can’t work.
37° Temperature temperature reaction rate What’s happening here?!
Enzymes and temperature Different enzymes function in different organisms in different environments 37°C temperature reaction rate 70°C human enzyme hot spring bacteria enzyme (158°F)