Energy, Enzymes & Metabolism
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72 Terms
what is energy?
Is the ability to do work. All work involves some form of energy transformation
What is potential energy?
Stored energy that has the capacity to do work
What is kinetic energy
Energy being transformed
Why must cells gain energy from their environment
cuz they lose energy as heat while performing work
what is heat
used to measure biological energy useage
what are the two laws of thermodynamics
total energy of a system and its surroundings is constant
entropy of the universe is continuously increasing
what is and endergonic change
when an object absorbs energy from its surroundings
what is an exergonic change
an object releases energy into its surroundings
what is entropy?
disorganization of energy unable to do work, chemical reactions procced in ways that create more entropy
how is thermal energy related to entropy
Thermal energy comes from the random motion of molecules, making it highly disorganized. Thermal energy is a form of energy; entropy describes how organized it is
why must living things constantly take in potential energy
as entropy increases, the energy available for work decreases. living things must take in potential energy to maintain their life processes and stay alive
what is metabolism?
all chemical reactions that occur in a living organism
what does metabolism allow organisms to do
allows life processes to occur (growth, movement, repair, reproduction, response)
what are the two types of reactions in humans
exothermic reactions: release heat
endothermic reactions: absorb heat
what is an exothermic reaction
occurs when reactants have more chemical energy than the products, excess energy is released as heat
Fill the blanks of the exothermic reaction graph
what are examples of exothermic reactions
combustion of methane and cellular respiration
what is activation energy
energy needed to break bonds in reactants before new bonds form.
why do exothermic reactions tend to proceed spontaneously once started
energy released is greater than the activation energy
what is an endothermic reaction
occurs when products have more energy than reactants
what do endothermic reactions require
continuous input of energy
Fill the blanks of the endothermic reaction graph
how does temperature affect molecular movement and reactions
as temperature increases, molecules move faster, causing more collisions and increasing the number of reactions and metabolism
why is maintaining a body temperature of 37 degrees C important
to keep metabolic rates functioning properly
what happens if there is too much energy or heat
can cause cell membranes to melt and proteins to denature
what are enzymes
protein catalysts that increase reaction rates by lowering the Ea
What does a graph show about enzymes and activation energy?
Enzymes lower the activation energy peak. The starting and ending energy levels stay the same.
what is an active site?
region on an enzyme where the substrate binds. Each enzymes has one or more active site
what is a substrate
reactant that binds to an enzymes active site
how does the lock and key model work
The substrate fits into the enzyme's active site because their shapes match. They form a temporary intermediate complex, which breaks down into a product and a free enzyme.
how do enzymes speed up reaction rates
by bringing substrates together in the correct way, lowering the activation energy needed for the reaction.
What does the lock and key diagram look like? (E-> E+S Complex-> E+P)
what is a cofactor
inorganic ion that binds to an enzyme and helps the substrate bind to it, and can alter the shape of active sites
examples of cofactors
Potassium, calcium, iron, zinc
What happens if an enzyme requires a cofactor but doesnt have one
it wont work
how do cofactors help enzymes
changing the shape of the enzymes active site
what is a coenzyme
organic molecular cofactor derived from vitamins
how do nutritional deficiencies affect coenzymes
result in non-functional enzymes altering metabolism
How are cofactors and coenzymes different from substrates and enzymes?
They can work with multiple enzymes, are not used up like substrates, and cannot catalyze reactions on their own like enzymes.
What is the lock and key model (1890)?
The enzyme acts like a lock, and only a specifically shaped substrate (key) can fit into its active site.
What is the induced fit model?
The substrate binds to the enzyme, causing its active site to change shape for a better fit.
What is the difference between the lock and key and induced fit models?
Lock and key: the active site already matches the substrate. Induced fit: the active site changes shape when the substrate binds.
How does temperature affect enzyme activity?
As temperature increases, molecules move faster and collide more, increasing reactions. If temperature gets too high, proteins denature and change the shape of their active sites.
What is coagulation?
when proteins denature permanently
How does pH affect enzyme activity?
Each enzyme has an ideal pH. Outside of that pH, the active site can denature, causing the enzyme to stop functioning properly.
Why does changing pH affect the active site?
Changing pH changes electrical charge attractions, including disrupting hydrogen bonds. This can change the shape of the active site.
Why do pepsin and trypsin have different ideal pH levels?
They work in different locations, so each has a different ideal pH.
Graph of pH vs enzyme reaction rate
How does substrate concentration affect enzyme activity?
As substrate concentration increases, reaction rate increases because there are more collisions between enzymes and substrates.
How does enzyme concentration affect reaction rate?
As enzyme concentration increases, the reaction rate also increases because more enzymes are available to react with substrates.
What happens when all enzyme active sites are occupied?
The enzyme becomes saturated because all active sites are engaged.
Graph of substrate/enzyme concentration vs enzyme reaction rate
What is an inhibitor?
a substance that prevents the formation of the enzyme-substrate complex.
What is a competitive inhibitor?
competes with the substrate for the active site. This results in fewer enzyme-substrate complexes and a lower reaction rate.
What is reversible inhibition?
occurs when a competitor temporarily binds to an enzyme and can later detach.
What is a non-competitive inhibitor?
binds to the enzyme at a location other than the active site, called the allosteric site. This changes the shape of the active site and makes the enzyme non-functional.
What are examples of non-competitive inhibitors?
Lead (Pb) and mercury (Hg) are heavy metal ions that act as non-competitive inhibitors. Cyanide (CN⁻) also inhibits enzymes that catalyze ATP synthesis.
Can non-competitive inhibition be reversible or irreversible?
Yes. Non-competitive inhibitors can bind temporarily (reversible) or permanently (irreversible).
How are enzymes named?
usually end in "-ase."
What are examples of enzyme names?
DNA helicase acts on DNA, sucrase acts on sucrose, lactase acts on lactose, and maltase acts on maltose.
What is thyroxin?
hormone from the thyroid gland that causes the body's tissues to increase the transport of oxygen into cells
How does thyroxin affect metabolic rate?
increases ATP synthesis, which increases the overall metabolic rate
What is a metabolic pathway?
is a linked, step-by-step series of chemical reactions that occur within a cell.
How are reactions connected in a metabolic pathway?
The product of one reaction becomes the starting substrate for the next.
What are the different types of metabolic pathways?
can be single pathways, branched pathways, or cyclical pathways.
What is feedback inhibition?
occurs when the product of one step acts as an inhibitor for a different step. (they are the end product that binds to the first enzyme)
How does feedback inhibition help maintain homeostasis?
allows the end product concentration to self-regulate, helping maintain homeostasis.
How can cells control metabolic pathways?
can activate or inactivate enzymes to add or remove pathways for molecules.
What conditions allow colliding molecules to react with each other?
Molecules must collide with enough energy to overcome activation energy. Higher temperatures increase molecular movement and collisions.
How are enzymes, substrates, and active sites related?
An active site is a region on an enzyme where a substrate binds, forming an enzyme-substrate (E-S) complex.
How do you identify the variables and controls in an experiment?
Independent variable: What you change.
Dependent variable: What you measure.
Controlled variables: What you keep the same.
Design an experiment to investigate the activity of enzymes. Make one for temperature, pH, and substrate and enzyme concentration. (Use the format change, measure, and keep the same)
Temperature: Change the temperature, measure enzyme activity, and keep pH, enzyme concentration, and substrate concentration the same.
pH: Change the pH, measure enzyme activity, and keep temperature, enzyme concentration, and substrate concentration the same.
Substrate concentration: Change the substrate concentration, measure enzyme activity, and keep temperature, pH, and enzyme concentration the same.
Enzyme concentration: Change the enzyme concentration, measure enzyme activity, and keep temperature, pH, and substrate concentration the same.