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BIOL 1000 Study Guide - Midterm Guide: Adenosine Triphosphate, Atp Hydrolysis, Phosphate

Course Code
BIOL 1000
Y I Sheng
Study Guide

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Energy and Enzymes Learning Outcomes
Define Key Terms:
Endergonic: Requiring the absorption of energy, a reaction that can only proceed if free energy
is supplied
Exergonic: Reaction that releases free energy, has a negative G
Free Energy (G): The energy in a system that is available to do work
Activated Carrier Molecule: Molecules that a e split C → A + B to release free eerg ut
only if there is an excess of C relative to its equilibrium concentration. Key examples are ATP,
Activation Energy: The initial input of energy required to start a reaction
Active Site: The region of an enzyme that recognizes and combines with a substrate molecule
Substrate: The particular reaction molecule or molecular group that an enzyme catalyzes
Reactants: The atoms or molecules entering a chemical reaction
Catalysis: Is the increase in the rate of a chemical reaction due to the participation of an
additional substance called a catalyst. With a catalyst, reactions occur faster because they
require less activation energy
Cofactor: An inorganic or organic non protein group that is necessary for catalysis to take place
Coenzyme: Organic cofactors that include complex chemical groups of various kinds
Enzyme: Protein that accelerates the rate of a cellular reaction
Competitive Enzyme Inhibitor: Binds to the active site of an enzyme
Noncompetitive Enzyme Inhibitor: Can bind to an enzyme with or without a substrate at
different places at the same time. It changes the conformation of an enzyme as well as its
active site, which makes the substrate unable to bind to the enzyme effectively so that the
efficiency decreases
Allosteric Site: A regulatory site outside the active site
Feedback Inhibition: In enzyme reactions, regulation in which the product of a reaction acts as
a regulator of the reaction.
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Describe, at a general level, metabolism [Comprehension]
The biochemical reactions that allow a cell or organism to extract energy to maintain
itself, grow, and reproduce. Most metabolic reactions fall into two types of pathways:
those that require energy and those that release energy.
Describe how oxidation-reduction reactions are important in cells, providing an example.
The potential energy contained in fuel molecules is released when the molecules lose
electrons, becoming oxidized. The electrons released from a molecule that is oxidized
are gained by another molecule becoming reduced. These are coupled reactions,
therefore one cannot happen without the other. During cellular respiration, redox
reactions basically transfer this bond energy in the form of electrons from glucose to
molecules called electron carriers. So an electron carrier is basically a molecule that
transports electrons during cellular respiration. By using electron carriers, energy
harvested from glucose can be temporarily stored until the cell can convert the energy
into ATP.
Explain, at a general level, the role of ATP in metabolism. [Comprehension]
ATP plays the role of providing a direct source of energy for cells to use. Cells store
energy in the form of ATP since they require a constant supply of energy and cannot
store energy as free energy. A living cell cannot store significant amounts of free energy.
Excess free energy would result in an increase of heat in the cell, which would lead to
excessive thermal motion that could damage and then destroy the cell. Rather, a cell
must be able to handle that energy in a way that enables the cell to store energy safely
and release it for use as needed. Living cells accomplish this by using the compound
adenosine triphosphate (ATP) . ATP is often called the "energy currency" of the cell and
can be used to fill any energy need of the cell.
Relate anabolic and cataoli pathas i a orgais’s etaolis. [Aalsis]
Anabolic Pathway Uses energy (endergonic). Uses simple molecules to build more
complex ones e.g. protein Synthesis
Catabolic Pathway releases energy (exergonic). Breaks down complex molecules into
simpler compounds e.g. starch broken down into glucose molecules.
Both pathways are linked through chemical energy. Energy released from the
breakdown of energy-rich molecules can harnessed by anabolic reactions which uses
energy to generate macromolecules. (Fig 4.14 page 83).
Explain how cells use activated carrier molecules to couple reactions in metabolism.
The energy released by the oxidation of food molecules must be stored temporarily
before it can be channeled into the construction of other small organic molecules and of
the larger and more complex molecules needed by the cell. In most cases, the energy is
stored as chemical bond energy in a small set of activated "carrier molecules," which
contain one or more energy-rich covalent bonds. These molecules diffuse rapidly
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