ENERGY & ENZYMES
LIFE PROCESSES REQUIREENERGY
• 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
energy
energy
Flow of energy through lifeLife is built on chemical reactions
transforming energy from one form to another
organic molecules → ATP & organic molecules
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 EquationsReactants: 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.
MetabolismChemical reactions of life
Bond must form between moleculesOccurs 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!
MetabolismBonds 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 & energySome chemical reactions release
energyexergonic
Some chemical reactions require input of energyendergonic
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
reactionENERGY• 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=XTUm-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 actionsubstrate fits into 3-D
structure of enzyme’ active site H bonds between substrate
& enzymelike “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
reac
tion
rate
What’shappening here?!
Enzymes and temperatureDifferent enzymes function in different
organisms in different environments
37°Ctemperature
reac
tion
rate
70°C
human enzymehot spring
bacteria enzyme
(158°F)
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pH
pH
reac
tion
rate
20 1 3 4 5 6 8 9 10
pepsin trypsin
What’shappening here?!
11 12 13 14
pepsin
trypsin