5.10-5.15 Flashcards
Define Kinetic Energy
energy of motion.
Define thermal energy
kinetic energy having to do with the random movement of particles within a substance.
Define potential energy
energy that matter possesses based on its location or structure.
Define chemical energy
potential energy available for release in a chemical reaction.
Define thermodynamics
energy transformations that occur in a collection of matter.
1st Law of Thermodynamics?
The law of energy conversion. It cannot be created or destroyed.
System vs. Surroundings
see 5.10
Why can energy not be recycled?
It is converted to thermal energy (random molecular motion) and released as heat.
Define entropy
a measure of disorder/randomness (a thermodynamic quantity representing the unavailability of a system’s thermal energy for conversion into mechanical work)
Second Law of Thermodynamics
The more randomly arranged a collection of matter is, the greater its entropy,»_space; energy conversions increase the entropy of the universe«
What thing has a small amount of entropy.
a cell. See 5.10
Define exergonic reaction
Releases energy (“energy outward”)
Endergonic reactions
Require a net input of energy and yield products rich in potential energy.
Examples of exergonic reactions
Combustion, cellular respiration.
Examples of endergonic reactions
photosynthesis (converts to energy rich glucose from sun energy)
While both are exergonic reactions, what differs between cellular respiration and combustion.
Combustion releases its energy quickly, where cellular respiration lets it go in steps.
What are considered “energy poor” compounds?
H2O, O2, CO2…
What is one definition of metabolism?
All of an organism’s chemical reactions.
Define metabolic pathway
a series of chemical reactions that either builds complex molecule or breaks down a complex molecule into simpler compounds (anabolism vs. catabolism)
Define energy coupling.
the use of energy from exergonic reactions to drive endergonic reactions.
Where is energy coupling crucial?
In cells, specifically ATP.
Cellular respiration is an exergonic process. Remembering that energy must be conserved, what do you think becomes of the energy extracted from food during this process.
Some of it is stored in ATP molecules; the rest is released as heat.
ATP stands for
Adenosine triphosphate– essential to all cellular work. It is made up of adenosine and three phosphate groups.
What makes ATP like a “compressed spring”
the negatively charged phosphate tails are pushed together.
Define phosphorylation
The hydrolysis of a phosphate group in ATP, which is then attached to another molecule
Why is phosphorylation important?
An exergonic reactions; it releases energy necessary for work in a cell.
Give an example of the cellular work phosphorylation causes.
Chemical: phosphorylation of reactants provides energy to drive the endergonic synthesis of products. Mechanical: the transfer of phosphate groups to special motor proteins in muscle cells causes the proteins to change shape and pull on other protein filaments, in turning causing the cells to contract.
When phosphorylation happens, what is left of ATP?
ADP (diphosphate)
Describe the ATP cycle.
Energy releasing in exergonic reactions, such as the breakdown of glucose during cellular respiration, is used to generate ATP from ADP (endergonic). The hydrolysis of the ATP releases energy that drives endergonic reactions.
How fast does the ATP cycle occur?
10 million molecules a second.
Explain how ATP transfers energy from exergonic to endergonic processes in the cell.
Exergonic processes phosphorylate ADP to form ATP. ATP transfers energy to endergonic processes by phosphorylating other molecules.
What prevents reactions from happening, if molecules always want to reach a stable, low energy state?
Energy barrier. it prevents all the molecules in our body from simply breaking down.
Define activation energy
What breaks the energy barrier; energy used to contort/weaken bonds to begin a reaction.
Metaphor for activation energy?
The amount of energy needed for reactant molecules to move “uphill” to a higher-energy, unstable state so that the “downhill” part of a reaction can begin.
Why is heat too inefficient in breaking the energy barrier.
(a) it is not controlled and (b) it can kill a cell. So how do we do the chemical reactions we need to live?
What is a more effective way to break the energy barrier?
Enzymes, the biological catalyst. They lower the activation energy needed to overcome the energy barrier.
Define substrate
the specific reactant that the enzyme acts on.
Define active site.
a pocket or a groove on the surface of the enzyme, where the substrate goes.
Define induced fit
the changing of the shape of the active site to orient the substrate correctly.
Describe the cycle of the enzyme, sucrase
Sucrose molecule goes to active site, connected by weak bonds. The enzyme does the induced fit, straining the bond of the sucrose and hydrolyzing it. Then the glucoses are released. millions of substrates per second.
Where do enzymes work the best
In neutral, 37 degree C (internal temperature) conditions, with exceptions.
Define cofactors
nonprotein helpers that bind to the active site and function in catalysis.
Examples of cofactors
iron, zinc, copper ions
When are cofactors considered coenzymes?
When they are organic molecules.
Can enzymes be switched on and off? Why?
Yes. If they couldn’t, everything would operate at once and lead to chaos. The molecules that do this are called inhibitors, and change the enzymes shape.
Define competitive inhibitor
A faux-substrate that blocks the active site of an enzyme. Solved by increasing substrate concentration.
Define noncompetitive inhibitor
Does NOT enter the active site. Binds to another site which changes the shape of the enzyme’s active site.
Explain how an enzyme speeds up a specific reaction
An enzyme lowers the activation energy needed for a reaction when its specific substrate enter its active site. With an induced fit, the enzyme strains the binds that need to break it positions substrates in an orientation that aids the conversion of reactants to products.
Define feedback inhibitation
A regulation tactic used by a cell to stop the overproduction of a certain product. Can be easily reversed and the metabolic pathway is opened back up.
Explain the value of feedback inhibition to a cell.
it prevents the cell from wasting valuable resources by synthesizing more of a particular product than is needed. (the activity of an enzyme is inhibited by the end product of a biochemical pathway)
What is ibuprofen made of? Same idea with penicillin, HIV medication, pesticides, deadly poisons (in extreme cases).
Enzyme inhibitors for prostaglandins– which makes swelling and cramps, etc.
Explain how enzyme inhibition in poisonous gas works.
poisons called nerve gases covalently bond (irregular!) to the active site of an enzyme in the body vital to the transmission of nerve impulses. The inhibition leads to rapid paralysis of vital functions and death.
What determines whether enzyme inhibition is reversible or irreversible?
Covalent bond or weak bond
