BIOC 385 - exam I || with 100% Error-free Answers.
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BIOC 385
What must be constant for a living organism to maintain a homeostatic condition that is far from equilibrium? correct answers constant input of energy
What do living systems abide by? correct answers the Laws of Thermodynamics; the spontaneity of biochemical reactions is expressed as ΔGo' in kJ...
what must be constant for a living organism to mai
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BIOC 385 - exam I || with 100% Error-free Answers.
What must be constant for a living organism to maintain a homeostatic condition that is far from
equilibrium? correct answers constant input of energy
What do living systems abide by? correct answers the Laws of Thermodynamics; the spontaneity
of biochemical reactions is expressed as ΔGo' in kJ/mol
energy charge correct answers a measure of [ATP], [ADP], and [AMP] in the cell and reflects
the amount of ATP for metabolic reactions
The energy available from redox reactions due to what? correct answers differences in the
electron affinity of two compounds and is an inherent property of each molecule based on
molecular structure
What are the two half reactions of a redox reaction? correct answers 1) oxidation reaction (loss
of electrons)
2) reduction reaction (gain of electrons)
What type of enzymes catalyze a redox reaction? correct answers enzymes that permit the energy
to be captured as work
What do photosynthetic autotrophs use energy from sunlight for? correct answers to
photooxideize biomolecules that initiate redox reactions using electrons supplied from H2O to
interconvert chemical energy and generate ATP
What do photosynthetic autotrophs and heterotrophs interconvert? correct answers chemical
energy using redox reactions to generate ATP from carbohydrates
NAD, FAD, and quinone are examples of what? correct answers electron carriers in numerous
biochemical reactions
first law of thermodynamics correct answers the total amount of energy in the universe does not
change; energy can neither be created or destroyed. Energy conversion in biological systems is
never 100% with the remainder of energy released often as heat
second law of thermodynamics correct answers in the absence of energy input, all natural
processes in the universe tend toward disorder, which is a measure of entropy (S). In chemical
terms entropy is the dispersion of energy; how energy is spread out (motion)
Gibbs free energy (g) and Equilibrium Constant (Keq) correct answers In the reaction A-->B,
ΔG = ΔGo'+ RT • ln [B]equilibrium / [A]equilibrium
or
ΔGo' = -RTlnKeq
,What direction does the reaction go if Keq > 1? correct answers the reaction proceeds
spontaneously to form C and D (left to right as written), then the value for ΔGo is negative
What direction does the reaction go if Keq < 1? correct answers the reaction favors the formation
of A and B (right to left as written), then the value of ΔGo is positive in this case
How can an unfavorable reaction proceed in vivo? correct answers unfavorable and favorable
reactions are coupled in vivo by sharing a common intermediate; the product of one reaction is
the reactant in a coupled reaction. An exergonic reaction (favorable) coupled to an endergonic
reaction (unfavorable) is an energetically favorable reaction
The ΔGo value for the coupled reactions is equal to? correct answers the sum of the ΔGo values
for the two separate reactions
What happens to the two phosphoanhydride bonds contained in ATP? correct answers can be
hydrolyzed to yield adenosine diphosphate and inorganic phosphate (ADP + Pi) or adenosine
monophosphate and pyrophosphate (AMP + PPi)
Very often when the transfer of a phosphoric or AMP group to react generates what? correct
answers a highly reactive intermediate
Two examples of cases in which phosphoanhydride bond hydrolysis does promote biochemical
process are usually related to protein conformational changes that accompany ATP and ATP
hydrolysis correct answers muscle contraction and ion transport against a concentration gradient
What is the energy charge range maintained by a cell? correct answers between 0.7 and 0.9 as a
result of regulated flux through anabolic and catabolic pathways
What are the primary factors that determine the flow or flux of metabolites through catabolic and
anabolic pathways? correct answers 1) Availability of substrates (diet or stored reserves)
2) Level of enzyme activity: enzyme levels (gene transcription, protein synthesis); catalytic
activity (allosteric control, covalent modification); compartmentation (subcellular or tissue
localization)
What are the four classes of macromolecules? correct answers proteins, nucleic acids,
carbohydrates, and lipids
What are the six primary metabolite groups? correct answers amino acids, nucleotides, fatty
acids, glucose, pyruvate, acetyl CoA
What are the seven small biomolecules? correct answers NH4+, CO2, NADH, FADH2, O2,
ATP, H2O
enzymes correct answers are a biological catalysts that alter reaction rates without changing the
overall change in free energy (ΔG) of the equilibrium constant (Keq) of the reaction
, transition state theory correct answers states that a reactant must reach an energy level required
for chemical transformation before product can be formed; enzymes lower the activation energy
What do cofactors and coenzymes provide? correct answers additional reactive group to the
enzyme active site that complement limited chemistry of amino acid side chains; cofactors are
inorganic ions whereas coenzymes are small organic compounds often derived from vitamins.
What does an enzyme active site provide? correct answers provide chemical environments that
facilitate catalytic reactions by excluding excess solvent the reactive functional groups of the
enzyme into close proximity to the substrate
What is an example fo the induced-fit model of enzyme catalysis? correct answers glycolytic
enzyme hexokinase, which undergoes a large conformational change upon binding of the glucose
substrate
What increased the catalytic efficiency of glycogen phosphorylase? correct answers noncovalent
binding of allosteric regulators, such as AMP, and by covalent attachment of a phosphoryl group
to Ser14
what do enzyme cofactors aid? correct answers the catalytic reaction mechanism within the
enzyme active site by providing additional chemical groups to supplement the chemistry of the
enzyme's amino acid functional groups
nitrite reductase correct answers has a Cu2+ ion cofactor in the enzyme active site that is
coordinated to two His residues that function to hold the metal cofactor in an optimal position for
catalyzing the reaction
coenzymes correct answers Organic enzyme cofactors and are often derived from vitamins,
which were discovered to be required for human health
The enzyme active site contains binding sites to select substrates and align the reactive groups
correct answers 1. Enzyme active sites provide an optimal orientation of the substrate(s) relative
to reactive chemical groups.
2. Enzyme active sites exclude excess solvent (H2O) that can interfere with the reaction.
What causes the enzyme active site of hexokinase to exclude H2O? correct answers upon
glucose binding, thereby preventing nonproductive phosphoryl transfer from ATP to H2O.
Glucose replaces water in the active site by occupying a similar volume and using similar weak
interactions for binding.
stimulatory enzyme regulation correct answers resulting in an overall increase in enzyme activity
inhibitory enzyme regulation correct answers resulting in a decrease in enzyme activity
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