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?!

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pepsin

trypsin