Biology: Chapter 5 (The Working Cell (Part 2))
In cells, what is usually the immediate source of energy for an endergonic reaction?
ATP
A form of passive transport. Molecules move across the plasma membrane using a transport protein.
Facilitated Diffusion
Which of these is exhibiting kinetic energy?
a space station orbiting Earth
The reaction ADP + P --> ATP is a(n) _____ reaction.
endergonic
Kinetic energy differs from chemical energy in that
kinetic energy is the energy of a moving object, whereas chemical energy is the potential energy of molecules.
Which of the following is highest in chemical energy?
one molecule of glucose
Chemical energy is a form of _____ energy.
potential
Most enzymes are _____.
proteins
For an enzyme to catalyze a reaction there must be a specific fit between the _____ and the enzyme's _____.
substrate ... active site
In the reaction A → B + C + heat,
the potential energy of the products is less than that of the reactant.
What is energy coupling?
the use of energy released from an exergonic reaction to drive an endergonic reaction
A form of passive transport. Molecules move across the plasma membrane by crossing the lipid bilayer.
Diffusion
The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell.
Endocytosis
What is the basic difference between exergonic and endergonic reactions?
Exergonic reactions release energy; endergonic reactions absorb it.
A vesicle inside the cell fuses with the plasma membrane and releases its contents outside the cell.
Exocytosis
What happens to the chemical energy that is extracted from molecules by cellular activities but that is not used for cellular work?
The energy contributes to the entropy of the system.
A pharmaceutical company wishes to focus on an enzyme to develop new medications. What type of study would be of the greatest benefit?
Understanding the enzyme's structure would help pharmaceutical companies design molecules that fit to the binding site and alter activity.
An enzyme is specific because the shape of its _____ matches only particular reactants.
active site
Cells store energy that they use for work in the _____.
arrangement of atoms within molecules
An _____ is considered a(n) catalystbecause it speeds up a chemical reaction without being used up.
catalyst
Azidothymidine (AZT) is an antiretroviral drug used in the treatment of HIV. It shares a structural similarity to a nucleotide. What might be the mode of action for this drug?
competitive inhibition
High temperatures or changes in pH can _____ an enzyme, causing it to lose its shape and biological activity.
denature
Which of these reactions requires a net input of energy from its surroundings?
endergonic
"Conservation of energy" refers to the fact that _____.
energy cannot be created or destroyed but can be converted from one form to another
A(n) _____ reaction occurs spontaneously.
exergonic
The energy for an endergonic reaction comes from a(n) _____ reaction.
exergonic
The reaction A --> B + C + heat is released in a(n) _____ reaction.
exergonic
When a cell uses chemical energy to perform work, it uses the energy released from a(n) ________ reaction to drive a(n) ________ reaction.
exergonic; endergonic
Which of these are by-products of cellular respiration?
heat and water
In cellular respiration, most energy is released and transferred to ATP when _____.
high-energy electrons "fall" to lower energy levels
What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?
hydrolisis
New drugs are being developed to lower levels of circulating cholesterol. A successful drug would be one that _____.
increases the rate of LDL receptor-mediated endocytosis
The _____ between an active site and its substrate often strains bonds and helps the reaction proceed.
induced fit
An enzyme _____.
is an organic catalyst
As a result of its involvement in a reaction, an enzyme _____.
is unchanged
A white blood cell engulfing a bacterium is an example of _____.
phagocytosis
Enzymes work by _____.
reducing activation energy
Kinetic energy is energy in motion. Potential energy is _____ energy.
stored
In a catalyzed reaction, a reactant is often called a(n)_____ .
substrate
What name is given to the reactants in an enzymatically catalyzed reaction?
substrate
You can recognize the process of pinocytosis when _____.
the cell is engulfing extracellular fluid
Energy is conserved. This means that in any system, _____.
total energy input equals total energy output
Most cellular work is accomplished by _____ energizing molecules by _____ them.
ATP ... phosphorylating
Requires energy from the cell. Molecules move against their concentration gradient.
Active Transport
What is the fate of the phosphate group that is removed when ATP is converted to ADP?
It is acquired by a reactant in an endergonic reaction.
Macrophages are white blood cells that roam the body searching for invading microbes. Inside macrophage vacuoles these invaders are destroyed. How do the microbes get inside the macrophages?
Microbes are engulfed into the macrophage via phagocytosis.
If you were working for a pharmaceutical company as part of a drug discovery team, which of these enzyme inhibitors would you suggest as a productive avenue for drug development?
a drug to treat high blood pressure that reversibly inhibits an enzyme catalyzing production of a chemical that causes blood vessels to contract
An enzyme speeds up reactions by lowering the_____ .
activation energy
In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?
cellular respiration
Glucose molecules provide energy to power the swimming motion of sperm. In this example, the sperm are changing
chemical energy into kinetic energy.
A(n) _____ , which is often a vitamin, binds to an enzyme and plays a role in catalysis.
coenzyme
Inhibition of an enzyme is irreversible when
covalent bonds form between inhibitor and enzyme.
Endocytosis moves materials _____ a cell via _____.
into ... membranous vesicles
