Chapter 1: Foundations of Biochemistry Flashcards
Who is the father of biochemistry?
Albert Lehninger
What are Albert Lehninger’s significant contributions?
that the citric acid cycle occurs in mitochondria, mech for oxidative phosphorylation, mitochondrial structure/function, bioenergetics
What does biochemistry study?
the chemistry responsible for accelerating reactions, organizing metabolism and signaling in cells, and storing and transferring information
What are the four building blocks of biochemistry?
sugars (monosaccharides), lipids (fatty acids), amino acids, nucleotides
Can biological molecules have more than one functional group?
Yes! Most biological molecules have several functional groups
What is a structural isomer? Are there differences in properties?
the same atoms but different order of bonding, different properties
What is a stereoisomer? Are there differences in properties?
molecules with the same chemical bonds but different configuration, different properties
What is an enantiomer? Are there differences in properties?
mirror imaged stereoisomer, have identical physical properties and react identically with achiral reagents, BUT may ave different biological activity
What is a diasteromer?
not mirror imaged stereoisomer, have different physical and chemical properties
What are the two types of diastereomers?
cis and trans geometric isomers
What does cis mean?
all groups are on the same side
What does trans mean?
all the groups are on the opposite side
Can cis geometric isomers rotate to be trans geometric isomers?
No! there is no freedom of rotation due to double carbon bond
How are the interactions between biomolecules specific?
macromolecules have unique binding pockets, thus the binding of chiral biomolecules is stereospecific
How does the enzyme hexokinase exhibit stereospecifcity?
the enzyme is specific for D-glucose (produced in the body), not L-glucose (made in the lab); this glucose must fit into a pocket of the enzyme and interact via noncovalent interactions
If lexapro is an enantio-pure drug and citalopram is a racemic mixture, what drug is stronger?
lexapro
What is a eutomer?
the active isomer
What is a distomer?
the inactive isomer
Half of all drugs and nearly 90% of recently approved drugs are?
racemic mixtures
Why are modern drugs usually racemic mictures?
cheaper, little to no greater therapeutic benefit
In what general cases would only one enantiomer in a drug be required?
when the other enantiomer is toxic to the body, when the other enantiomer causes undesirable side effects
What is the 1st law of thermodynamics?
energy can neither be created nor destroyed
What is the 2nd law of thermodynamics?
a chemical or physical process goes spontaneously in the direction of greater disorder/entropy
What is it called when a reaction breaks down something? Does is produce or consume energy?
catabolic, energy-producing
What is it called when a reaction synthesizes something? Does is produce or consume energy?
anabolism, energy-consuming
What three things must living systems do to maintain organization?
extract usable energy, release useless energy, and increase entropy in the universe
What do all reactions go towards?
equilibrium
What is ΔG at equilibrium?
0
What can ΔG tell us about a reaction?
which direction the reaction will go as it reaches equilibrium
Can ΔG tell us how fast a reaction will proceed?
No!
What is ΔG(knot)?
ΔG at standard conditions of 1 M reactions and products, 25°C, 1 atm, and pH 0
What are some things that you can do to speed up a reaction?
increase temperature, increase reactant, decrease product, lower activation barrier, couple the reaction to a fast one
What is used instead of ΔG(knot) in biochemistry?
ΔG(knot)(prime)
What does ΔG(knot)(prime) indicate?
that the reaction is at the biochemical standard state of pH 7, [H2O] = 55 M
What does it mean if the Keq is above 1.0?
ΔG is negative and the reaction proceeds forward
What does it mean is the Keq is 1.0?
ΔG is zero and the reaction is at equilibrium
What does it mean if the Keq is below 1.0?
ΔG is positive and the reaction proceeds in reverse
Why can individual steps in a pathway not be favorable, but the overall pathway is?
ΔGs are additive in multistep pathways, the overall pathway must have a -ΔG
What can enzymes not do?
alter ΔG or go against equilibrium
What are the advantages of an enzymatic catalyst?
acceleration under mild conditions, high specificity, possibility for regulation, coupling reactions to ATP hydrolysis, avoids side reactions, substrate channeling
Why are chemical couplings so important?
they allow for otherwise unfavorable reactions by making the overall ΔG negative
What are the two steps of ATP group transfer?
1) ATP transfers phosphate to substrate, raising its energy (group transfer)
2) the phosphate leaves the substrate, making it go back to a lower energy state
What is a metabolic pathway?
a pathway that produces energy or valuable materials
What is a signal transduction pathway?
a pathway that transmits information
Where is the most common point of regulation?
at the first enzyme in a pathway
