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All forms of energy can be placed in two categories name them:
- Potential energy
- Kinetic energy
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Potential energy
Is stored energy such as chemical bonds, concentration gradient, charge imbalance, etc
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Kinetic energy
the energy of movement
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Metabolism
sum total of all reactions in an organism
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anabolic reactions
complex molecules are made from simple molecules; energy input is required
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catabolic reactions
complex molecules are broken down to simpler ones and energy is released
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First law of thermodynamics
energy is neither created nor destroyed. When energy is converted from one form to another, the total energy before and after the conversion is the same
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Second law of thermodynamics:
When energy is converted from one form to another, some of that energy becomes unavailable to do work.
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No energy transformation is 100% _____
efficient
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Entropy
a measure of the disorder in a system
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It takes energy to _____ ____ on a system. Unless energy is applied to a system, it will be _____ ______
- impose order
- randomly arranged or disordered
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If ΔG is negative...
If ΔG is positive...
- If negative, free energy is released
- If positive, free energy is consumed
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Exogernic
reactions release free energy aka (-G): Catabolism/ complexity decreases/ entropy increases
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Endergonic
reaction consumes free energy (+G): anabolism/ complexity (order) increases
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ATP ____ & ____ free energy
captures and transfers
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ATP releases a large amount of energy when _____
hydrolyzed
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ATP can_______ or donate phosphate groups to other molecules
phosphorylate
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____ is a nucleotide whose hydrolysis yields free energy
ATP
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ATP+H2O→
ADP+Pi+free energy
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The formation of ATP is ______
endergonic
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Formation and hydrolysis of ATP couples ____ & _____ reactions
exergonic and endergonic reactions
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Exergonic reactions (3)
- releases energy
- cell respiration
- catabolism
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Endergonic reactions (4)
- requires energy
- active transport
- cell movement
- anabolism
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Enzymes
Catalysts that speed up the rate of a reaction without being altered by the reactions
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Most biological catalysts are _____ (_____) that act as a framework in which ______ can take place
- enzymes (proteins)
- reactions
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Activation energy changes the reactants into ____ forms with ____ free energy. These forms are called _____ ____ _____
- unstable
- higher
- transition state intermediates
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Activation energy can come from _____ the system. The reactants will have more _____ energy
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How do enzymes lower the energy barrier
By bringing reactants together
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What holds the enzyme substrate complex together? (3)
- hydrogen bonds
- electrical attraction
- covalent bonds
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enzyme + substrate (will end up)=
enzyme + product
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The enzyme may change when bound to the substrate, but?
returns to its original form
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The possible ways the enzyme-substrate complex can be formed
- Orientation
- Physical strain
- Chemical charge
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How do enzymes orient substrate molecules?
by bringing together the atoms that will bond
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Physical strain
Enzymes can stretch the bonds in substrate molecules, making them unstable
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Chemical charge
Enzymes can use electrostatic attraction to temporarily add chemical groups to substrates
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Shape of enzyme active site allows? (lock and key)
a specific substrate to fit
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Binding of substrate to the active site depends on? (3)
- Hydrogen bonds
- attraction and repulsion of electrically charged groups
- hydrophobic interactions
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Many enzymes change shape when they bind to the substrate, this is called ____ __
induced fit
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The rate of catalyzed reaction depends on _____ ____
substrate concentration
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_______ of an enzyme is usually much _____ than ______ of a substrate.
- Concentration
- lower
- concentration
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At ______, all of the enzyme is bound to the substrate (______ ____)
- saturation
- (maximum rate)
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Inhibitors
regulate enzymes by binding to it and slowing reaction rates
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Which inhibitors regulate metabolism
naturally occurring inhibitors
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Reversible inhibition
inhibitor bonds noncavalently to the active site and prevents substrate from binding
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competitive inhibitors
compete with the natural substrate for binding sites
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When concentration of competitive inhibitor is reduced, what happens
it detaches from the active site
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Noncompetitive inhibitors
bind to the enzyme at a different site (not the active site)
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Irreversible inhibition
Inhibitor covalently bonds to side chains in the active site, this permanently inactivates the enzyme
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Initial symptoms poison by nerve gas
- runny nose
- tightness of breath
- constriction of pupils
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intermediate symptoms of poison via nerve gas
- nausea
- drooling
- loss of bodily functions
- vomiting
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final symptoms of poison via nerve gas
- twitching and jerking
- suffocation (death)
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Antidote for nerve gas poisoning
Atropine, a muscarinic ACTH receptor which is a competitive antagonist
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Every enzyme is most active at a particular pH. Why is this? Give an example
- pH influences the ionization of functional groups
- Ex: at low pH COO- may react with H+ to form COOH (uncharged). This affects folding and thus enzyme function.
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Give two reasons why enzyme have an optimal temprature
At high temps, noncovalent bonds begin to break & enzymes can lose its tertiary structure and become denatured
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Phenyletonuria (PKU)
Genetic disorder due to a mutation in the gene for phenylalanine hydroxylase (PAH)
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PAH is required to degrade excess ______ to the amino acid _____. Without this conversion _____ is converted to ________. This leads to (2)?
- phenylalanine
- tyrosine
- phenylalanine
- phenylpyruvate
Leads to: mental disability & seizures
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Phenylalanine conversion to phenylpyruvate can be treated by
eliminating soda from diet
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Which has more potential energy, glucose or carbon dioxide?
Glucose, because it has a lot more bonds
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Anabolic steroids involves taking simple things like proteins and chaining them together via _____ bonds and forming _____ ____
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Heat death
maximum entropy, when there is no longer usable energy available to do work in all the universe
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The universe is an ______ system & will always move toward ______
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Human beings are capable of taking energy and matter in making us ______ systems
open
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The body constantly couples ______ & ______ reactions to get things done. Cellular respiration would be an example of such a reaction
endergonic & exergonic
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Cellular respiration begins with glucose and ends with _____. We get free energy from the______ of bonds. That free energy is used in different reactions for ex. putting a _____ on ADP to make ATP
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The Na/K pump uses ______ reactions gains potential energy from the ______ _____. Potential energy can be used to chain _____ bonds.
- exergonic
- concentration gradient
- peptide bonds
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What binds to the active site of adenylyl cyclase?
What does AC convert it into?
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How would you make cAMP faster?
make more adenylyl cyclase
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Reversible inhibition is inhibition of an enzyme without ______ the enzyme. If the inhibitor comes off, the ______ _____ of the enzyme returns to normal.
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Competitive inhibition involves inhibitor binding to the _____ ____ and out-competing the natural ______. If the substrate can't bind, it can't _____ the reaction. This is a form of ______ ______.
- active site
- substrate
- catalyze
- reversible inhibition
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Name two factors that determine whether a substrate or the competitive inhibitor binds at a certain site
Concentration & affinity for the binding site
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If a substrate or inhibitor has a much higher _____ for a binding site, it can out-compete the other other. If _____ is evenly matched, the _____ levels will tip the scale.
- affinity
- affinity
- concentration
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State an example of allosteric inhibition
noncompetitive inhibition
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Noncompetitive inhibition involves the inhibitor not binding at the ____ ____ but at a ______ _____. When this occurs, it changes the _____ _____ of the enzyme, making it unfit for binding with the ______. The result: we are unable to _____ a reaction/ slowed reaction rate
- active site
- different site
- tertiary structure
- catalyze
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Allosteric activation: a molecule binds to a _______ _____ and ______ the activity of the enzyme
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Example of an irreversible inhibition
nerve gas
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Nerve gas works by affecting an enzyme called __________ which is found at _______ synapses. These synapses are synapses that release ______ and are (the synapses) found in ______.
- acetylcholinesterase
- cholinergic synapses
- acetylcholine
- muscles
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*Acetylcholinesterase catalyzes a reaction that breaks ______ to an ______ & _______
*=not tested
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The result of the reaction catalyzed by ACTHesterase is that _______ ceases to be a ________. Meaning?
- ACTH
- neurotransmitter
- It won't bind to receptors.
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What happens if ACTHesterase (enzyme) is disrupted?
ACTH concentration goes up.
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How does nerve gas work? *=not tested (optional)
- The enzyme has a pocket that acetylcholine goes to be broken/ it catalyzes a breakage of the bonds that hold ACTH together
- Nerve gas will settle in that pocket and form covalent bonds rendering the enzyme useless. ACTH remains unbroken and begins to pile up.
- The solution: make more acetylcholinesterase (takes time)
- *Introduce atropine which will block muscarinic ACTH receptors. Diaphragm will continue to malfunction and muscles will continue to twitch but, this should keep the heart from stopping which will ultimately keep you alive.
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