Biology/Biochemistry (Ours) Flashcards
Mutation changes within the interior of a protein (ex) Arg change to Leu) and its influence on delta G BCR
Hydrophobic effect is a major driving force in protein folding as well as favorability of amino acid interactions. Look at whether residue is positive or negative and whether it is favored in the nonpolar or acidic protein interior. If favorable interactions, then more spontaneous/favorable reactions, lower delta G
irreversible (comp/noncomp) vs. reversible noncompetitive inhibition affect on kinetics: V vs. [S] BCR
The kinetics seen under these conditions would be similar to both of these interactions because the net effect would be loss of active enzyme available for reaction. If enzyme concentration is effectively lowered, Vmax will be reduced. If Km were affected, it would increase, indicating that the substrate-enzyme interaction has been compromised in some way.
Which category of enzymes will irreversibly modify their substrate? BCR
A protease Proteases are enzymes that cleave their substrates at specific sites, permanently removing a part of the protein. This is practically irreversible.
Kinase BCR
Adds a phosphate to its substrate and this modification can be reversed by a phosphatase that will remove the phosphate.
Acetylase BCR
Will add an acetyl group
Phosphatase BCR
will remove the phosphate.
What does increasing temp do to the ability of an enzyme to bind to its substrate? BCR
Increasing the temp of an enzyme’s surroundings may or may not affect the likelihood of an enzyme binding its substrate. Increasing temp = increase kinetic energy of sub = higher chance of entering active site of enzyme BUT be aware of “beyond temp of denaturation”
Enzymes and changing pH BCR
Changing the pH of the solution to a non-optimal level will affect the change of the protein side chains and enzyme function
Enzymes and mutating acidic residues to basic residues BCR
will change the charge of the active site substantially and likely affect the subs ability to bind to the active site
Enzymes and altering shape/size of sub BCR
will decrease the sub’s ability to effectively bind to the active site
For a given enzyme concentration at low sub concentration, how does the reaction rate change as the sub concentration increases? BCR
Linearly At low sub concentrations, the rxn rate increases linearly as the sub concentration increases. At or near saturation levels, the rxn rate begins to level off and does not change regardless of how much substrate it added. This is called the max velocity of the reaction rate or Vmax.
Cooperativity - proteins BCR
- a protein must be composed of multiple protein subunits that are able to interact with one another, or less likely, should have multiple active sites within the same protein. - if no cooperativity, protein may have one subunit or multi non-cooperative subunits - cooperative enzymes usually exhibit sigmoidal curves - this involves changes in binding affinity when a sub is
Lineweaver-Burk plot and competitive inhibitors BCR
-the y-intercept represents 1/Vmax and the x-intercept represents -1/Km. Bc competitive inhibitors do not change the Vmax and instead increase the Km, this plot with differing concentrations of comp inhib will show intersecting lines that share a common y-intercept.
Lineweaver-Burk plot’s slope and competitive inhibitors BCR
Slope: dependent variable (y) is 1/v, the independent variable (x) is 1/s, they-intercept (b) is 1/Vmax, and the slope (m) is Km/Vmax. Comp inhib increases Km, while non-comp inhib reduces Vmax. As both Km and Vmax contribute to the slope, both modes of inhibition will produce a change in slope of the L-B plot
Production of NADPH BCR
-by the pentose phosphate pathway - cells use it as the e- donor in reductive biosynthesis and in the process of detoxification of reactive oxygen species
NADH+ BCR
is an e- acceptor in the oxidative metabolism of nutrients
Lineweaver-Burk plot and non-competitive inhibitors BCR
a non-comp inhib binds to the allosteric site on the enzyme, effectively turning the enzyme off, but it doesn’t affect the ability of the enzyme to bind to substrate. Thus, Vmax will be decreased and Km will remain the same. A decrease in Vmax = an increase in the y-int (1/v) and Km is the x-int, which doesn’t change in this case.
Enzymes alter the rate of chemical reactions by all of the following methods EXCEPT:
altering substrate primary structure The primary structure of a protein substrate is the amino acid sequence of the protein. Enzymes cannot alter primary structures of protein, but can co-localize substrates, alter local pH, and alter substrate shape.
Ornithine is an amino acid that is found in cells, but not incorporated into proteins. Which of the following statements gives the most fundamental reason why ornithine is unlikely to be found in proteins synthesized in vivo? BCR
There is no codon for it in the standard genetic code. without a corresponding codon in the genetic code, an amino acid cannot take part in the process of protein translation from an mRNA transcript.
What is a catalyst, cofactor, substrate, & activator? BCR
1) enzymes = catalysts = speed up reaction 2) is a non-protein chemical compound or metallic ion that is required for an enzyme’s activity as a catalyst; increases rate of reaction 2) the substance on which an enzyme acts 3) molecules that bind to enzymes and increase their activity. They are the opposite of enzyme inhibitors.
The statement that the “XYZ” assay is highly specific means that it:
can distinguish “XYZ” activity from the many other enzymatic reactions in a cell enzymes such as “XYZ” are highly specific both in the reactions that they catalyze and in their choice of substrates and therefore catalyze only a single chemical reaction or occasionally a set of closely related reactions.
acetyl coenzyme A is the main input where?
is the main input of the citric acid cycle
protein levels relate most directly to _____ levels BCR/BR
mRNA
Phases of Cell Cycle & the order BR
Interphase, metaphase anaphase, telophase
Do circulating erythrocytes do contain DNA? BR
mammalian erythrocytes (red blood cells) lose their nuclei during maturation. Therefore, circulating erythrocytes can’t contain DNA that could affect endothelial cell growth, hypothetically.
The process of culturing bacteria often involves inoculation of cells on a noncellular, agar-based medium. Such a methodology would NOT result in growth of animal viruses because animal viruses: BR
are obligate parasites. viruses can only reproduce in a host cell, and are therefore obligate intracellular parasites.
How would the following nucleotides bond?
nucleotides are linked to one another by phosphodiester bonds between the sugar base of one nucleotide and the phosphate group of the adjacent nucleotide in a way that the 5’ end bears a phosphate, and the 3’ end a hydroxyl group.
During an action potential, the movement of sodium ions into a neuron causes the neuronal membrane to do which of the following?
Depolarize
the movement of sodium ions into a neuron during an action potential results in opening of more voltage-gated sodium channels, causing further depolarization
glucocorticoids
act on skeletal muscle causing the breakdown of muscle proteins
The most rapid rate of gluconeogenesis will most likely occur in the body when:
BCR
gluconeogenesis is the pathway for the synthesis of glucose from other metabolic compounds and thus it is activated when the body’s stores of carbohydrates are low.
A translated polypeptide is cleaved into the mature form and secreted from the cell. The cleavage most likely takes place in?
BR
Endomembrane system
secreted proteins, such as insulin, are cleaved into mature form within endomembrane system.
**make sure to know role of endomembrane system in processing of secreted proteins.**
Despite the effects of diabetes, the brains of diabetic patients still receive adequate nourishment. This is most likely because the brain uses:
BR
glucose is the main fuel for brain cells, and since the brains of diabetic patients receive an adequate amount of glucose, the brain must use an insulin-independent mechanism for glucose uptake.
A certain bacterium was cultured for several generations in medium containing 15N, transferred to medium containing 14N, and allowed to complete two rounds of cell division. Given that the bacterium’s genome mass is 5.4 fg when grown in 14N media and 5.5 fg when grown in 15N medium, individual bacteria with which of the following genome masses would most likely be isolated from this culture?
BR
5.4 fg and 5.45 fg
DNA replication is semi-conservative. Therefore, after the first round of cell division the genome mass in each bacterium will be 5.45 fg (one DNA strand will contain 15N and the other strand 14N). Following the second round of cell division, half of the bacteria will have a genome mass of 5.4 fg (14N exclusively) and the other half a mass genome of 5.45 fg (14N in one DNA strand and 15N in the other)
Know how to calculate the number of offspring with a particular phenotype from a parental cross
ex) Assume that K and M are two unlinked genes that affect hearing. The dominant K allele is necessary for hearing, and the dominant M allele causes deafness regardless of the other genes present. Given this, what fraction of the offspring of parents with the genotypes KkMm and Kkmm will most likely be deaf?
5/8
Based on the Punnett square analysis, 10 out of 16 or 5/8 of all offspring are likely to be deaf.
An RNA molecule has 1500 bases. What is the maximum number of amino acids it can encode?
500
each amino acid is encoded by three bases, so 1500/3 is 500, which is the maximum of amino acids the RNA molecule can encode.
thermodynamics
is the study of the energetics of chemical rxns
kinetic & potential energy
What is the most important potential energy storage molecule in all cells?
ATP, which stores energy in ester bonds between its phosphates
First law of thermodynamics / law of conservation of energy
energy of the universe is constant
if energy of system decreases, energy of rest of surroundings must increase
Second Law of Thermodynamics
disorder, or entropy (s) , of the universe tends to increase
Spontaneous rxns tend to increase the disorder of the universe
Gibbs Free Energy / free energy
delta G increases with increasing bond energy (delta H = enthalpy) and decreases with increasing entropy. Which one would be more favorable? One with decreasing free energy bc entropy increases.
determins whether a rxn is favorable (spontaneous = neg delta G or nonspon = pos delta G)
exergonic vs. endergonic
rxns with neg delta G = exergonic = energy exits the system
rxns with pos delta G = endergonic = energy is added
exothermic vs. endothermic
exothermic = neg delta H = liberate heat
endothermic = pos delta H = input of heat
How can delta G be negative if delta G naught (delta G*` = in standard conditions) is positive, (which indicates that the reaction is unfavorable at standard conditions)?
rxn may be favorable if the ratio of the concentrations of reactants to products is sufficiently large to drive the reaction forward (so if delta G is more neg than delta G naught is pos), regardless of the sign of their delta G naught.
Does Keq indicate the rate at which a rxn will proceed?
BCR p. 42
Keq only indicates the relative concentrations of reagents once equilibrium is reached, not the rxn rate (how fast equilibrium is reached).
When Keq is large, which has a lower free energy: products or reactants?
A larger Keq means that more products are present at equilibrium. Equilibrium tends towards the lowest energy state. Hence, when Keq is large, products have a lower free enegy than reactants.
When Q is large, which has lower free energy: products or reactants?
The size of Q says nothing about the properties of reactants and products. Q (products/reactans concentrations) is calculated from whatever the intial concentrations happen to be. It is Keq that says something about the nature of reactions and products, since it describes their concentrations after equilibrium has been reached.
There are two factors that determine whether a reaction will occur spontaneoulsy (delta G = negative) in the cell:
1) the intrinsic properties of the rreactants and products (Keq)
2) the concentration of reactants and products (RT LnQ)
3) in the lab, ther eis a 3rd factor: temp; if Ln Q is negative and the temp is high enough, delta G will be neg, regadless of the value of delta G naught
What does “spontaneous” say about rate of reaction?
Spon. means that a reaction is energetically favorable, but it says nothing about the rate of rxn
chemical kinetics
transition state (TS)
Activiation Energy (Ea)
BCR p. 43
study of reaction rates
unstable, short, takes a lot of energy
energy required to produce the transition state
catalyst ____ Ea and without changing the _____. it ____ the transition state and is _____ with each reaction cycle. ____ are a biological catalysts.
lowers the Ea of a rxn without changing the delta G; they increase rate of rxn (have a kinetic role, NOT a thermodynamic one)
it stabalizes the transition state
regenerated
Enzymes
photosynthesis
photoautorophs
chemoheterotrophs
the process by which plants store energy from the sun in the bond energy of carbohydrates
plants are _____, bc they use energy from the light to make thier own food
we are _____, bc we use erngy of chemicals produced by other living things
Oxidation
loss of electrons
1) gain oxygen atoms
2) loss of H
3) loss of e-
reduction
the gain of e-
1) loss of Oxygen
2) gain of H
3) gain of e-
Will an enzyme alter the concentration fo reagents at equilibrium?
No. It will affect only the rate at which the reactnats and products reach equilibrium.
catabolism
anabolism
oxidative catabolism
is the process of breaking down molecules –> “cata-strophe”
is “building-up” –> “add-a”
the way we extract energy from glucose; we break down glucose by oxidizing it
redox pair
when one atom gets reduced, another myst be oxidized
ex) glucose oxidation
Bronsted-Lowry Acids & Bases
Acids: proton (H+) donors
Bases: proton (H+) acceptors
Lewis Acids & Bases
Acids: e-pair acceptors
Bases: e-pair donors
ex) AlCl3 + H2O
Conjugate Base
Conjugate Acid
when a Bronsted-Lowery acid donates a H+, the remaining thing is a con base
when a B-L base bonds with a H+, it becomes a con acid
strength of an acid
Ka = acid ionization (or acid-dissociation) constant
pKa
strength of an acid is direclty related to how much the products are favored over the reactants
Ka = [products] / [reactants] = equilibrium expression for an acid-dissociation reaction = the larger the Ka, the stronger the acid
the lower the pKa, the stronger the acid
pKa = -logKa
**Kb & pKb exist**
What acid would dissociate to the greatest extent in water?
the acid with the largest Ka value
polyprotic
has more than one proton to donate
amphoteric
What compounds are amphoteric?
substance that can act as either a base or an acid
Amino Acids
pH equations & pKa/b equations
pH = -log[H+]
pOH = -log [OH-]
pH + pOH = 14
pKa/b = -log Ka/b
**the lower the pKa, the stronger the acid**
What would contain the lowest concentration of H3O+ ions if you’re given pH?
Since pH = -log [H3O+], we know that [H3O+] = 1/10 pH. This fraction is the smallest when the pH is the greatest.
So, look for the highest pH.
buffer solutions
a solution that resists pH when a small amount of acid or base is added
buffering capacity = presence of weak acid and conjugate base (vise versa)
most important buffer system = bicarbonate buffer system (H2CO3 -> H+ + HCO3-
describe the function of enzymes
by decreasing the energy of the transition state, enzymes increase the amt of product formed per unit time
In general, know what get’s reduced & oxidized in a reaction
BCR p. 45
do example probelms !
Acidic Glu has a pKa value of 2.3 and found near neutral Ile residue. What will be the effect on the pKa of the Glu reside if a nutation subsitutes a positively charged Lys residue for the Ile residue?
the pKa will decrease due to favorable ionic interactions b/w the deprotonatd Glu and Lys residues.
The sub of a pos charged lysine for a neautral isoleucine would help stabilize Glu in its deprotonated, neg-charged state. Bc it would be more stable, it is more likely to give up its proton (becomes more acidic) and the pKa would decrease.
proteins are biological macromolecules that act as…
enzymes, hormones, receptors, channels, transporters, anitbodies, support strucutres inside/outside cell
composed of 20 diff amino acid links
amino acid structure
side chains of amino acids
BCR p. 63
the unique feature of each amino acid is its side chain (variable r-group), which gives it the physical and chemical properties that distinguish it from the other nineteen
chemical properties to know of amino acids
shape, ability to hydrogen bond, and ability to act as acids or bases (which determines their charge at physiologial pH)
Aspartic Acid & Glutamic acid
Acidic amino acids; have a carboxylic acid functional group
could be seen as asparate and glutamate = anionic (deprotonated) form of each molecule
Lysine, Arginine, Histidine
basic amino acids
Lys: pKa = 10, cationic (protonated) at physiological pH,
Arg: pKa = 12, cationic (like Lys),
His: pKa = 6.5, protonated or deporotonated at pH 7.4 = “HIS goes both ways”
at 7.4 pH (physiological pH): -COOH or -NH2 (RCOO-) = anionic and RNH3+ = cationic
hydrophobic (nonpolar) amino acids
either have alkyl or aromatic side chains
found on interior of folded globular proteins, away from water
Glycine - aliphatic side chain
Alanine - aliphatic side chain
Valine - aliphatic side chain
Leucine - aliphatic side chain
Isoleucine - aliphatic side chain
Phenylalanine - aromatic side chain
Tryptophan - aromatic side chain
polar amino acids
r-group polar enough enough to from hydrogen bonds with h2o, but which doesn’t act as an acid or base -> hydrophilic
serine - hydroxyl groups residuews are often modified by the attachment of a phosphate group by a reg enzyme, a kinase = change in strucutre (protein regulation)
threonine - hydroxyl groups residuews are often modified by the attachment of a phosphate group by a reg enzyme, a kinase = chaneg in structure (protein regulation)
tyrosine - hydroxyl groups residuews are often modified by the attachment of a phosphate group by a reg enzyme, a kinase = change in structure (protein regulation)
asparagine - amide derivative of aspartic acid
glutamine - amide derivative of glutamine
sulfur-containing amino acids
cysteine - contains a thiol, polar
methionine - thioether, nonpolar
proline
amino group is covalently bound to its nonpolar side chain, creating a secondary alpha-amino group and ring structure
protien folding = important with this
general overview of acidic, basic, polar, and nonpolar amino acids
Amino acids are composed of an ___ group (the ______ acid) and a ____ group (the ____).
carboxylic acid, basic group, amine
Henderson-Hasselbalch equation
the mathematical formula that describes the relatinoship between pH, pKa, and the position of equilibrium in an acid-base reaction
When the ____ of a solution is ___ than the ___ of an acidic group, the acidic group will moslty be in its ____ form.
BCR p. 68
pH
less
pKa
protonated
how is a peptide bond formed?
backbone
residue
a peptide bond is fromed between the carboxyl group of one amino acid and the alpha-amino group of another amino acid with the loss of h2o
in a polypeptide chain, the N-C-C-N-CC = backbone
an individual amino acid is a residue when it is part of a polypeptide chain
Enzyme Class and reaction (10 types)
Changes in the Apparent Vmax and Km in response to various types of inhibition
Graph of competative inhibitor
Noncompetitive inhibitor
Bind at allosteric site, not active site
Decreases Vmax (adding more enzyme will increase the measured Vmax)
Km is not affected (substrate can still bind to AS)
–> overall: (decrease Vmax, while having no effect on Km for the inhibited enzyme)
Uncompetitive inhibition
decrease Vmax, while decreasing Km for the inhibited enzyme
Only binds to enzyme-substrate complex
Bind to allosteric sites
Decreases Vmax (limiting amt of available enzyme-substrate complex which can be made to product)
Km decreases
Enzyme-complex has greater affinity for the inhibitor → enzyme will have greater affinity for substrate –> km decreases
fatty acid oxidation
chylomicrons (fat and lipoprotein) are transported via lympathic system and BS to liver, heart, etc
this TG is then hydrolyzed to liberate free FA (which can undergo beta oxidation)
process begins at outer mito membrane with activation of fatty acid
rxn catalyzed by acyl-coA synthetase (requires 2 ATP to generate fatty acyl-CoA - transported into mitochondrion)
** fatty acyl-coa is activated fatty acid
in matrix, fatty acyl-coA goes through beta oxidation (each round cleaves 2 carbon acetyl coA from the molecule; final round: cleaves 4 carbon acyl-coA to make 2 acetyl-coA) –> feeds into krebs cycle
each turn of beta cycle produces 1 FADH2 and 1 NADH; each turn of krebs makes 1 FADH2 and 3 NADH
Break down fatty acid: calculate how many times we need fatty acid oxidation
(#C in fatty acids / 2) - 1
unsaturated vs saturated fatty acid oxidation
Unsaturated FA: already have DB, so you isomerize it (only need 1 oxidation vs 2 for saturated)
Difference: less energy (1 oxidation instead of 2 oxidations)
Oxidizing unsaturated requires less energy!!
synthesis of malonyl coA (–> fatty acid synthesis)
takes place in cytoplasm
acetyl-coA is first activated with co2 and atp; acetyl-coA carboxylase –> malonyl-coA
fatty acid synthesis (part 2)
bcr p. 154
fatty acid synthase (enzyme)
1) acetyl coa binds to ACP - then shifted to another domain with cysteine residue; malonyl-coa binds to ACP), 2) acetyl group condenses with malonyl group as malonyl is decarboxylated, 3) ACP domain now holds 4 Carbon unit, undergoes 2 reductions (requires 2 NADPH - from pentose phosphate pathway, has reducing power), 4) saturated four-carbon acyl unit shifts to the domain with cysteine residue and another malonyl-coA binds to ACP, 5) process repeats: 4 c unit condenses with malonyl as co2 is lost, 2 reductions occur, and the now 6 c chain is shifted to cysteine residue
- goal: make 16 c fatty acid
fatty acid synthesis (part 3)
image describes elongation process; process was described in part 2 slide
ketogenesis
bcr p. 151
during long term starvation, blood glucose falls
fats are oxidized to form acetyl-coa
levels of acetyl coa increase
some acetyl coa feeds into krebs
remaining acetyl-coAs react to form ketone bodies - acetone, acetoacetate, beta-hydroxybutyrate (ketogenesis)
ketone bodies: can enter the brain- this is the primary source of energy for brain during starvation (and be reconverted to acetyl-coa (acetyl coa can then enter krebs cycle)
type I diabetes: if patient doesnt receive insulin injection for a while, patient relies on fatty acid oxidation for acetyl-coa to feed krebs
but bc acetyl-coa levels are so high, many of them become ketone bodies (acidic –> ketoacidosis)
protein catabolism
PROTEASE: break down proteins into individual AA
From individual AA we can form new proteins or break down into amino group
- Amino group can go off and form nitrogenous compounds (nucleotides) and urea for excretion
remaining carbon skeleton (alpha-keto acid) –> water and co2, or converted to glucose (glucogenic AA - low glucose levels) or acetyl-coA (ketogenic AA)
metabolism summary
BCR p. 156
- cells prefer to use carbohydrates as fuel
- when blood sugar is high: cells will take up glucose and make ATP via glycolysis, liver and muscle cells will store glucose as glycogen (glycogenesis), liver can take some of the acetyl-coa generated by PDC to make fatty acids –> triglycerides and stored in adipose tissue
- when Blood sugar is low: liver will break down stored glycogen (glycogenolysis) and release glucose into bloodstream (also begin gluconeogenesis to be sent into bloodstream - taken up by other cells and used in glycolysis to make ATP)
- if starved state goes past point where all glycogen stores are used (12-24 hours), fatty acid breakdown occurs (triglycerides from adipose tissue are broken down into fatty acids and run beta oxidation; liver uses glycerol to make glucose in gluconeogenesis; some acetyl-coa made in beta oxidation fuels krebs; some is made into ketone bodies)
- proteins and amino acids as fuel: carbon skeleton of amino acids can be used in gluconeogenesis (glucogenic amino acids) or to make acetyl-coa and ketone bodies (ketogenic AA0
hydrophobicity
pass through membrane by simple diffusion
molecule shown below: hydrophobic
half-life
From the graph, it takes 0.5 h for the plasma concentration of urea to fall by one-half (100 ng/mL to 50 ng/mL). If it took five half-lives for urea to be considered eliminated from the body, 0.5 h should be multiplied by five = 2.5 hours
competitive inhibitor
Compete with substrate for binding at active site
Can be overcome by adding more substrate
Vmax isn’t affected; Km increases
Enzyme has greater affinity for inhibitor in free form → enzyme has lower affinity for the substrate → km increases
Arachidonic acid is a fatty acid contained in cell membranes. The structure of arachidonic acid is:
In which component of the cell membrane would arachidonic acid most likely be found?
**cholesterol vs. triglycerides vs. phospholipids vs. Peptidoglycan layer**
Phospholipids
Cholesterol is an abundant component of animal cell membranes, but it is a steroid, not derived from fatty acids such as arachidonate. Triglycerides could contain a fatty acid like arachidonate, but they are not membrane components. Peptidoglycans are not found in eukaryotes, only bacteria, and do not consist of fatty acids.Phospholipids are abundant components of the plasma membrane and contain esters of many different fatty acids.
Which of the following is NOT a valid resonance contributor of the cationic intermediate of the reaction shown?
D
Choice D has a hydrogen atom attached to the same carbon as the chlorine, but is missing the hydrogen bonded to the bottom carbon of the ring that choices A, B, C, and the original cation all have. Since atoms and not only electrons have been moved, choice D cannot be considered a resonance structure of the original cation.
Hardy-Weinberg equation
only be used to describe the frequencies of autosomal recessive or dominant traits or conditions, not changes in chromosome number!
aldosterone
steroid that increases sodium uptake from and potassium secretion into the filtrate in distal tubule (stimulated by low na, low bp, low blood volume - all problems that will be rectified with this steroid)
released from adrenal cortex
also stimulates ADH secretion so more h2o can be taken up from filtrate
- if you didn’t have aldosterone: water and sodium loss, decreased blood volume and decreased blood pressure; In response to decreased blood pressure, renin secretion would increase, not decrease
check out aphys notes!
Which form of the amino acid GABA does not predominate at any pH?
uncharged form B does not predominate at any pH since the pKa of the carboxyl group is lower than the pKa of the protonated amino group, making the former group the stronger acid. The titration of GABA from acidic to basic pH would therefore result in the following changes in its protonation state:
LOOK AT IMAGE BELOW
As a result, form A predominates at pH < 2.3, form C at 2.3 < pH < 9.7, and form D at pH > 9.7.
nucleoside vs nucleotide
side: ribose/deoxy w/ purine/pyrimidine linked to 1’ carbon
tide: phosphate esters of nucleosides, with phosphate groups joined to ribose ring by 5’ hydroxy group
