BCH 451 TEST 1 EXAM QUESTIONS WITH WELL VERIFIED
ANSWERS 2024/2025
What are the 4 building blocks of biochemistry?
-sugars (monosaccharides)
-lipids (fatty acids)
-amino acids
-nucleotides
What are structural isomers?
same atoms but different order of bonding; different properties
What are stereoisomers? What are the 2 types?
molecules with same chemical bonds but different configuration and different properties
-enantiomers and diastereomers
What is an enantiomer?
mirror image of molecule
-have identical physical properties and react identically with achiral reagents, but may
have different biological activity
What is a diasteromer?
not a mirror image
-geometric isomer
-have different physical and chemical properties
What does cis mean?
groups on the same side
,What does trans mean?
groups on opposite sides
Why are interactions between biomolecules specific?
macromolecules (enzymes, antibodies, etc.) have unique binding pockets and binding
of chiral biomolecules are stereospecific
Why are racemic mixtures preferred by some doctors?
they are cheaper but may not show any greater therapeutic benefit
-BUT sometimes an enantiomer fixes a different thing than another one
What is catabolism vs anabolism?
catabolism: energy-producing, breakdown
anabolism: energy-consuming, biosynthetic
What does free energy (delta G) tell you? What doesn't it tell you?
the direction of reactions as they go toward equilibrium, BUT NOT how fast a reaction
proceeds (kcat)
What is equilibrium in terms of Kf, Kr, and delta G?
Kf=Kr
delta G = 0
What are ways to speed up a reaction?
-increase temperature
-increase reactant
-decease product by downstream reactions
,-lower activation barrier by enzyme catalysis
-couple the reaction to a fast one (activation via ATP)
What does free energy and Keq measure?
the direction of processes
What is delta G^0 equation?
delta G naught = -RTlnKeq
What is the difference between between G^0 and G^'0?
G^0: standard conditions of 1 M reactants and products; pH = 0
G^'0: biochemical standard state; pH=7
If K'eq is greater than 1, what sign is G^'0 and which direction does the reaction
want to go?
G^'0 is negative
proceeds forward
If K'eq is 1, what sign is G^'0 and which direction does the reaction want to go?
G^'0 is 0
is at equilibrium
If K'eq is less than 1, what sign is G^'0 and which direction does the reaction
want to go?
G^'0 is positive
proceeds in reverse
What does actual delta G determine?
, direction in cells
**for a reaction at concentrations other than standard
What is G actual equation?
Gactual = G^'0+RTln([C][D]/[A][B])
**A+B=C+D
so the Gactual is products over reactants
What must the free energy for the total reaction be for a reaction to occur in a
multistep manner (Gactual)?
overall pathway must have a negative free energy change
What do enzymes do and not do? (3 things in total)
-do not alter delta G^0
-cannot go against equilibrium
-lower the activation energy G
What are the 6 things that enzymatic catalysis offers?
-acceleration under mild conditions
-high specificity
-possibility for regulation
-coupling reactions to ATP hydrolysis
-avoids side reactions
-substrate channeling
What is the benefit of energy coupling via ATP?
ANSWERS 2024/2025
What are the 4 building blocks of biochemistry?
-sugars (monosaccharides)
-lipids (fatty acids)
-amino acids
-nucleotides
What are structural isomers?
same atoms but different order of bonding; different properties
What are stereoisomers? What are the 2 types?
molecules with same chemical bonds but different configuration and different properties
-enantiomers and diastereomers
What is an enantiomer?
mirror image of molecule
-have identical physical properties and react identically with achiral reagents, but may
have different biological activity
What is a diasteromer?
not a mirror image
-geometric isomer
-have different physical and chemical properties
What does cis mean?
groups on the same side
,What does trans mean?
groups on opposite sides
Why are interactions between biomolecules specific?
macromolecules (enzymes, antibodies, etc.) have unique binding pockets and binding
of chiral biomolecules are stereospecific
Why are racemic mixtures preferred by some doctors?
they are cheaper but may not show any greater therapeutic benefit
-BUT sometimes an enantiomer fixes a different thing than another one
What is catabolism vs anabolism?
catabolism: energy-producing, breakdown
anabolism: energy-consuming, biosynthetic
What does free energy (delta G) tell you? What doesn't it tell you?
the direction of reactions as they go toward equilibrium, BUT NOT how fast a reaction
proceeds (kcat)
What is equilibrium in terms of Kf, Kr, and delta G?
Kf=Kr
delta G = 0
What are ways to speed up a reaction?
-increase temperature
-increase reactant
-decease product by downstream reactions
,-lower activation barrier by enzyme catalysis
-couple the reaction to a fast one (activation via ATP)
What does free energy and Keq measure?
the direction of processes
What is delta G^0 equation?
delta G naught = -RTlnKeq
What is the difference between between G^0 and G^'0?
G^0: standard conditions of 1 M reactants and products; pH = 0
G^'0: biochemical standard state; pH=7
If K'eq is greater than 1, what sign is G^'0 and which direction does the reaction
want to go?
G^'0 is negative
proceeds forward
If K'eq is 1, what sign is G^'0 and which direction does the reaction want to go?
G^'0 is 0
is at equilibrium
If K'eq is less than 1, what sign is G^'0 and which direction does the reaction
want to go?
G^'0 is positive
proceeds in reverse
What does actual delta G determine?
, direction in cells
**for a reaction at concentrations other than standard
What is G actual equation?
Gactual = G^'0+RTln([C][D]/[A][B])
**A+B=C+D
so the Gactual is products over reactants
What must the free energy for the total reaction be for a reaction to occur in a
multistep manner (Gactual)?
overall pathway must have a negative free energy change
What do enzymes do and not do? (3 things in total)
-do not alter delta G^0
-cannot go against equilibrium
-lower the activation energy G
What are the 6 things that enzymatic catalysis offers?
-acceleration under mild conditions
-high specificity
-possibility for regulation
-coupling reactions to ATP hydrolysis
-avoids side reactions
-substrate channeling
What is the benefit of energy coupling via ATP?
