Download Metabolism and Enzyme Notesheet

Name ____________________________________ Date ____________ Period _____
METABOLISM AND ENZYMES
Raven Ch. 8
Big Idea 2: BIOLOGICAL SYSTEMS UTILIZE FREE ENERGY AND MOLECULAR BUILDING
BLOCKS TO GROW, TO REPRODUCE AND TO MAINTAIN HOMEOSTASIS.
Essential Knowledge:
 Cell membranes are selectively permeable due to their structure.
 Growth and dynamic homeostasis are maintained by the constant movement of molecules across membranes.
 Eukaryotic cells maintain internal membranes that partition the cell into specialized regions.
 All biological systems from cells and organisms to populations, communities and ecosystems are affected by
complex biotic and abiotic interactions involving exchange of matter and free energy.
 Homeostatic mechanisms reflect both common ancestry and divergence due to adaptation in different
environments.
Flow of energy through life
 Life is built on chemical reactions
 transforming energy from one form to another
Metabolism
 Chemical reactions of life
 ___________________ between molecules
 dehydration synthesis
 synthesis
 _________________ reactions
 ___________________ between molecules
 hydrolysis
 digestion
 _________________ reactions
Chemical reactions & energy
 Some chemical reactions _________________
 _________________
 digesting polymers
 hydrolysis = catabolism
 Some chemical reactions require _________________
 _________________
 building polymers
 dehydration synthesis = anabolism
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Exergonic
_______________
_______________
vs.
Endergonic
_______________
_______________
G = ______________________________________________________________________

Organisms require energy to live
 Where does that energy come from?
 coupling exergonic reactions (_______________ energy) with endergonic reactions
(_________________ energy)
___________________
___________________
What drives reactions?
 If reactions are “downhill”, why don’t they just happen spontaneously?
 _______________________________________
Activation energy
 Breaking down large molecules requires an initial input of energy
 _________________________
 large biomolecules are stable
 must absorb energy to break bonds
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Too much activation energy for life
 Activation energy
 amount of energy needed to destabilize the bonds of a molecule
 moves the reaction over an “energy hill”
Reducing Activation energy
 __________________
 reducing the amount of energy to start a reaction

Enzymes vocabulary:
So what’s a cell got to do to reduce activation energy?
 get help! … chemical help…______________
Enzymes
 __________________________
 proteins (& RNA)
 facilitate chemical reactions
 ______________ rate of reaction
without being consumed
 ______________ activation energy
 don’t change ___________________
released or required
 required for most biological reactions
•highly _____________________
 thousands of different enzymes in cells
•______________ reactions of life
______________________
 reactant which binds to enzyme
 enzyme-substrate complex: temporary association
_____________________
 end result of reaction
_____________________
 enzyme’s catalytic site; substrate fits into active site
Properties of enzymes
 _____________________
 each enzyme works with a specific substrate
 chemical fit between active site & substrate
 H bonds & ionic bonds
 _____________________
 single enzyme molecule can catalyze thousands or more reactions per second
 enzymes unaffected by the reaction
 Affected by _____________________
 any condition that affects protein structure
 temperature, pH, salinity
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Naming conventions

Enzymes named for reaction they catalyze
 ____________ breaks down sucrose
 ____________ break down proteins
 ____________ break down lipids
 DNA ____________ builds DNA
 adds nucleotides to DNA strand
 ____________ breaks down
proteins (polypeptides)
Lock and Key model
 __________________ model of enzyme action
 substrate fits into 3-D structure of enzyme’ active site
 H bonds between substrate & enzyme
 like “key fits into lock”
Induced fit model
 __________________ model of enzyme action
 3-D structure of enzyme fits substrate
 substrate binding cause enzyme to change shape leading to a tighter fit
 “_____________________________”
 bring chemical groups in position to catalyze reaction
How does it work?
 Variety of mechanisms to lower activation energy & speed up reaction
 ____________________________
 active site orients substrates in correct position for reaction
 enzyme brings substrate closer together
 ____________________________
 active site binds substrate & puts stress on bonds that must be broken, making it easier to
separate molecules
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