Ch. 6.3, 6.4 & 6.5Energy & Enzymes
_______________________required to start the reaction
energy level of reactants
energy content
ofmolecules
energy level of products
progress of reaction
An _____________________ reaction Sparks ignite gas
high
low
6.2 All Chemical Reactions Require Activation Energy to Begin
https://www.youtube.com/watch?v=p-27I_osoaw&feature=related (History Lesson on Endo and Exo)http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/chemreac/energychangesrev1.shtml (ex of rxn)
(b) An exergonic reaction
6.3 How is Energy Transported Within Cells organisms powered by chemical energy supplied by ____________ breakdown of glucose energy transferred to _____________________________(i.e. ATP)
charged by exergonic rxns and drive endergonic rxns (i.e. rechargeable batteries ATP recycled approx. 1,400X/day (marathon runner uses a lb.
of ATP/min
Dehydration synthesis uses energy when making ATP
from ADP.
_________________________– energy carrier molecules that ______________energetic electrons & H+ ions
donate high-energy electrons to other molecules NADH, FADH2
Coupled Reactions Link Exergonic with Endergonic Reactions
_____________reaction - exergonic rxns provide energy needed to __________endergonic rxns
___________________ - plants use sunlight (____gonic) to drive _______gonic synthesis of high-energy glucose molecules from lower-energy reactants (CO2 + H2O)
________________ – organisms break down glucose into CO2 + H2O(_____gonic) to drive synthesis of proteins, amino acids (_____gonic)
energy is always __________________every time it is transformed energy released (exergonic) must always exceed energy needed (endergonic)
https://www.youtube.com/watch?v=7IqgrcBkGRU
activation energy determines the ________ at which a reaction occurs https://www.youtube.com/watch?v=VbIaK6PLrRM
Blue = exothermicGreen = endothermic
some important chemicalreactions are too slow or have a high activation energy
6.4 How Do Enzymes Promote Biochemical Reactions?
reactants
reactants
exothermic
_____________ – substances that __________rates of chemical reactions w/o being used up or permanently altered
https://www.youtube.com/watch?v=hNl5WYSM5DE (Elephant Toothpaste)https://www.youtube.com/watch?v=v9ju2rZ8YmM (how catalytic converters work – 10 min)
Enzymes are Biological Catalysts not advantageous to speed up dozens of rxns at once; so it is a _________________
_______________– natural catalysts (mostly proteins)
each catalyzes only a few types of rxns (most only catalyze 1 with specific molecules)
exergonic & endergonic rxns can be catalyzed
ATP synthase + ATPasehttps://www.youtube.com/watch?v=W3KxU63gcF4 (ATP Synthase)
Structure of Enzymes Allows Them to Catalyze Specific Reactions
____________ of enzyme _______________ its ____________ (just like proteins) structure – determined by a.a. sequence/twisted/folded
shape and charges of a.a. that form active site determines what molecules can enter (amylase starch not cellulose; pepsin & trypsin) some catalyze tens of thousands of rxns/sec and some act much slower https://www.youtube.com/watch?v=lfuOQZJ_MIM (firefly)
Enzymes, Like All Catalysts, Lower Activation Energy
reactions occur in_____; each step catalyzed by different enzymes ____________activation energy overall reaction can occur at
body temp
https://www.youtube.com/watch?v=r1ryDVgx0zw
https://www.youtube.com/watch?v=tI69AVRW0DU (related to digestion)
How Are Enzymes Regulated?
metabolism – sum of all the ________________________in a cell
metabolic pathways – reactions that are linked together - ________________ step acts as the ________________________ step
i.e. _______________ (synthesis of high energy molecules i.e. glucose)
i.e. glycolysis (begins breakdown of glucose)
Initial reactant Intermediates End products
PATHWAY 1
PATHWAY 2
enzyme 1 enzyme 2 enzyme 3 enzyme 4
enzyme 5 enzyme 6https://www.youtube.com/watch?v=l_vvz5fD00M – photo & resp.
Cells must regulate metabolic pathways by controlling ____ produced.
a) type of enzymesb) quantity of enzymesc) activity levels of enzymes
for a given ____________ of enzyme, as substrate levels increase, the rxn rate ______________ until active sites of all enzymes are being continuously occupied by new substrate
________that code for enzymes can turn _____________ - marathon runners & high-carb meals b4 competitions- glucose enters blood & triggers metabolic rxns (i.e.
pancreas releases insulin) - insulin turns on genes that code for 1st enzyme in pathway
that breaks down glucose
Some enzymes only synthesized at ________________ in organisms life (i.e. lactase)
some enzymes are synthesized in _______________ and then activated when needed (i.e. protein digesting pepsin & trypsin – work best in acidic conditions)
http://lgfl.skoool.co.uk/content/keystage3/biology/pc/learningsteps/PAELC/launch.html
Enzyme Activity May be Controlled by Competitive or Noncompetitive Inhibition
Reactions ______________ by competitive inhibition and noncompetitive inhibition to prevent 1) substrates from being _________ and 2) producing _________________ product
____________________ inhibition: substance that is not the enzyme’s normal substrate can _________________to active site of enzyme (competing for a spot)
- structural similarities
i.e. _________________________ (block active site of acetylcholinesterase; excess acetylcholine overstimulates muscles causing paralysis) https://www.youtube.com/watch?v=-gIqZ8IxctE
i.e. _______________________ inhibits synthesis of bacteria cell walls; ________________________________ inhibits synthesis of molecules that contribute to swelling, pain, fever.
____________________ inhibition: molecule binds to a site on enzyme different from active site; ___________________; enzyme less able to catalyze rxn
https://www.youtube.com/watch?v=PILzvT3spCQ (short comparison)
_____________________: _______________________ inhibition where enzymes ___________ easily between 2 different ________ that either activate or inhibit the enzyme (i.e. ADP)
https://www.youtube.com/watch?v=d5fDEUhjo-M
___________________: form of ________________ regulation; causes metabolic pathways to ______________________________ when its concentration reaches an optimal level (thermostat)
https://www.youtube.com/watch?v=DHZtOKyMPRY (feedback inhibition)
As levels of isoleucine rise,isoleucine binds to the regulatorysite on enzyme 1, inhibiting it
intermediates
enzyme 1 enzyme 2 enzyme 3 enzyme 4 enzyme 5
enzyme 1
isoleucine
isoleucine(end product)
threonine(initial
reactant)
Activity of Enzymes is Influenced by Their ____________________
enzymes have a narrow range of conditions (_________________) in which they function optimally (H-bonds btwn polar a.a.)
_______________: when enzymes lose 3-D structure required to function properly
human cellular enzymes work best around pH 7.4; human digestive enzymes work best around pH 2
__________________ affects rate of enzyme catalyzed reactions (_____________ by _______________ temps; ________________ by ________________ temps)
http://lgfl.skoool.co.uk/viewdetails_ks3.aspx?id=452
For pepsin, maximumactivity occurs atabout pH 2
For most cellularenzymes, maximumactivity occursat about pH 7.4
For trypsin, maximumactivity occurs atabout pH 8
rate of
reaction
Effect of pH on enzyme activitypH
106543210 7 8 9
fast
slow
For most human enzymes,maximum activity occursat about 98.6-F (37-C)
rate of
reaction
fast
slow
Effect of temperature on enzyme activitytemperature
60 (-C)0 4020140 (-F)32 68 104