Unit 3.1 AP Biology

constant input of energy

all living systems require this

life

requires a highly ordered system and does not violate the second law of thermodynamics

first law of thermodynamics

matter/energy cannot be created or destroyed, only transferred or transformed

second law of thermodynamics

every energy transfer increases the entropy of the universe

entropy

measure of randomness/useless energy

input; loss

Energy _______ must exceed energy ______ to maintain order and to power cellular processes.

release; require

Cellular processes that ________ energy may be coupled with cellular processes that ______ energy.

death

Loss of order or energy flow results in this.

Energy-related pathways in biological systems

are sequential to allow for a more controlled and efficient transfer of energy-- A product of a reaction in a metabolic pathway is generally the reactant for the subsequent step in the pathway.

ATP

adenosine triphosphate; stored in bond between 3rd P

bonds

energy is stored here -- released when formed, absorbed when broken

types of energy

heat, kinetic, potential, activation, mechanical, etc

redox reactions

reductions and oxidations

reduction

electrons are gained, creating a more negative charge

oxidation

electrons are lost, creating a less negative charge

metabolism

the totality of an organism’s chemical reactions; includes anabolic and catabolic reactions

anabolic reactions

endergonic rxns -- build complex molecules when energy is absorbed; not spontaneous and there is greater energy in the products (positive △G)

catabolic reactions

exergonic rxns -- break down molecules when energy is released; spontaneous and there is a greater energy in the reactants (negative △G)

enzyme

any of several complex proteins that act as biological catalysts that facilitate chemical reactions in cells by lowering the activation energy -- decrease amount of E needed to start a reaction

active site

the structure of enzymes includes this bonding site, which specifically interacts with substrate molecules (reactants)

shape and charge

For an enzyme-mediated chemical reaction to occur, these factors of the substrate must be compatible with the active site of the enzyme.

substrate

like each key is specific to each lock, each _________ is specific to the active site.

weak

There are ____ bonds so they can be easily broken and products can easily come out

activation energy

the energy needed to start a chemical reaction

structure and function

of enzymes, they contribute to the regulation of biological processes

why save energy?

less work needed to be done; more energy can be used for something else

function or efficiency

Change to the molecular structure of a component in an enzymatic system may result in a change of the what of the system?

Denaturation

of an enzyme occurs when the protein structure is disrupted, eliminating the ability to catalyze reactions; loses structures 2 to 4 -- without folding, the enzyme can't function

Environmental temperatures and pH

these factors outside the optimal range for a given enzyme will cause changes to its structure, altering the efficiency with which it catalyzes reactions

reversible

In some cases, enzyme denaturation is _______ , allowing the enzyme to regain activity

Environmental pH

can alter the efficiency of enzyme activity, including through disruption of hydrogen bonds that provide enzyme structure

concentrations

The relative ___________ of substrates and products determine how efficiently an enzymatic reaction proceeds; sped up when substrate increased, can add more enzymes to keep efficiency up

Higher environmental temperatures

increase the speed of movement of molecules in a solution, increasing the frequency of collisions between enzymes and substrates and therefore increasing the rate of reaction.

Competitive inhibitor molecules

can bind reversibly or irreversibly to the active site of the enzyme

Noncompetitive inhibitors

can bind allosteric sites, changing the activity of the enzyme (changes the shape of the active site)

allosteric sites

site other than active site on an enzyme

e) catabolism

the cellular process of breaking down large molecules into smaller ones is defined as...
a) catalysis
b) metabolism
c) anabolism
d) dehydration
e) catabolism

c) They consume energy to build up polymers from monomers

Which of the following is (are) true for anabolic pathways?
a) They do not depend on enzymes
b) They are usually highly spontaneous chemical reactions
c) They consume energy to build up polymers from monomers
d) They release energy as they degrade polymers to monomers

a) anabolic reactions

Which of the following types of reactions would decreased the entropy within a cell?
a) anabolic reactions
b) hydrolysis
c) diffusion
d) digestion
e) catabolic reactions

a) endergonic

A chemical reaction that has a positive △G is correctly described as
a) endergonic
b) endothermic
c) enthalpic
d) spontaneous
e) exothermic

e) can do no work

A system at chemical equilibrium
a) consumes energy at a steady rate
b) releases energy at a steady rate
c) consumes or releases energy, depending on whether it is endergonic or exergonic
d) has zero kinetic energy
e) can do no work

b) The reaction proceeds with a net release of energy

Which of the following is true for all exergonic reactions?
a) The products have more total energy than the reactants.
b) The reaction proceeds with a net release of energy
c) The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants
d) A net input of energy from the surroundings is required for the reactions to proceed
e) The reactions are rapid.

b) It is combined with ADP to regenerate ATP

Hydrolysis of ATP releases energy, which results in the production of ADP and inorganic phosphate. What is commonly the ultimate fate of inorganic phosphate produced in the cytosol?
a) It is secreted as waste
b) It is combined with ADP to regenerate ATP
c) It is phosphorylated
d) It is hydrolyzed to release additional energy

b) Enzymes increase the rate of a reaction by lowing the activation energy barrier

Which of the following statements regarding enzymes is true?
a) Enzymes increase the rate of a reaction by making the reaction more exergonic
b) Enzymes increase the rate of a reaction by lowing the activation energy barrier
c) Enzymes increase the rate of reaction by reducing the rate of reverse reactions
d) Enzymes change the equilibrium point of the reactions they catalyze
e) Enzymes make the rate of a reaction independent of substrate concentrations

b) binds substrates for the enzyme

The active site of an enzyme is the region that
a) binds allosteric regulators of the enzyme
b) binds substrates for the enzyme
c) binds noncompetitive inhibitors of the enzyme
d) is inhibited by the presence of a coenzyme or a cofactor

b) by changing the shape of the enzyme's active site

How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?
a) by binding at the active site of the enzyme
b) by changing the shape of the enzyme's active site
c) by changing the free energy change of the reaction
d) by acting as a coenzyme for the reaction
e) by decreasing the activation energy of the reaction

b) it may alter the tertiary structure of cellular enzymes

A severe fever can result in death if not brought under control because
a) it may destroy the primary structure of cellular enzymes
b) it may alter the tertiary structure of cellular enzymes
c) it may increase the rate of cellular chemical reactions
d) it may result in binding inappropriate substrates by cellular enzymes

c) competitive inhibition

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
a) denaturization of the enzyme
b) allosteric inhibition
c) competitive inhibition
d) saturation of the enzyme activity
e) insufficient cofactors

d) ATP is a molecule that acts as an intermediary to store energy for cellular work

Which of the following is the most correct interpretation of the figure above (ATP Cycle)?
a) Inorganic phosphate is created from organic phosphate
b) Energy from catabolism can be used directly for performing cellular work
c) ADP + Pi are a set of molecules that store energy for catabolism
d) ATP is a molecule that acts as an intermediary to store energy for cellular work
e) Pi acts as a shuttle molecule to move energy from ATP to ADP

c) recycle the energy used for cellular work
or
a) recycle ADP and phosphate

Cells use the ATP Cycle shown in the figure above to
a) recycle ADP and phosphate
b) recycle energy released by ATP hydrolysis
c) recycle the energy used for cellular work
d) move energy from ATP to ADP