ENERGY & ENZYMES

LIFE PROCESSES REQUIRE ENERGY Energy = the ability to move or change matter.

What are some forms of energy? Light Heat Chemical Electrical

From food webs to the life of a cell energy

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

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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

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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. Um-75-PL4http:// 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)

Activation Energy with and without an enzyme

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)

7 pH reaction rate pepsintrypsin What’s happening here?! pepsin trypsin