Diagnostic MCAT (science) Flashcards
What letter is equillibrium constant?
K
What is pK and what does the size of the number indicate?
pK = -log(K)
Dissociation constant of acid into its conjugate base or vice versa.
Smaller number indicates stronger acid/base.
What is the formula that ties in the equillibrium constant of acids and bases?
Ka * Kb = Kw
Kw applies to water, ig this is only for water.
Put 50cm^2 into m^2.
.005 m^2 (4 decimal places)
Relate capacitance, voltage, and charge.
Relate average current, time, and charge.
Q = CV
I = Q/∆t
If a capacitance or voltage is changed in a problem and the respective new value of the new capacitance or voltage is asked, what is the equation?
C1V1=C2V2
Relate wavelength to frequency 2 ways.
What is the speed of light?
f = 1/λ
(inverse relationship)
f*λ = c(speed of light)
c = 3E8 m/s
Protonation and deprotonation
Protonation: Addition of a proton (H+)
Deprotonation: Removal of a proton (H+)
As pH is raised, the most acidic group ____ ____.
deprotonates first
This is because the most acidic group has the lowest pKa, meaning it is the most willing to lose a proton (H⁺) at lower pH values.
Acidity and pKa are ____ ____.
inversely related
What change in physical state (ex. solid to liquid, liquid to gas, liquid to solid, gas to liquid) takes the most energy/heat.
Vaporization (liquid to gas)
Enantiomers
Pairs of chiral molecules. Same physical/chemical properties.
Ex:
Dextrorotatory (rotates light clockwise, labeled (+)), the other being Levorotatory (rotates light counterclockwise, labeled (-)).
Chirality
Can’t be superimposed on another molecule, same size but assymetrical. (Right glove left glove).
Same atomic formula and connectivity.
Similar physical and chemical properties but can differ in different conditions.
Refers to one molecule.
Blood flow speed is 30 cm/s in a 1.6 cm diameter tube. Tube is reduced to .8 cm diameter, what is the new speed?
A1V1=A2V2
Area = pir^2
Answer is 120 cm/s
Does Ca 2+ have an electron configuration equal to that of a noble gas? (Need periodic table)
Yes, loses two electrons through positive 2 charge, move 2 columns left on the periodic table.
6C12 (6 on top 12 on bottom of Carbon)
What about 14 on bottom?
How many protons electrons neutrons?
Protons:6
Neutrons:6
Electrons, depending on + or -, if C+, 5 electrons.
If Carbon has 14, then 6 protons, 8 neutrons.
Electronegativity
Periodic table trick…
Ability for atom to attract electrons toward itself in chemical bond.
Increase in electronegativity as moves to the right and up (periodic table).
Temperature’s relationship to volume…
Pressure relation to volume…
As temp increases volume increases (if heat is added).
Inverse relationship –> Doubling pressure will halve the volume.
Formula relating moles volume and concentration.
moles = CV –> moles = volumeconcentration
Le Chateleirs Principle.
Formula with Ki, E, EI and I.
In a reversible process, the application of stress in the system will prompt a response that relieves stress.
Ex. Adding more [I] (inhibitor) will prompt the production of more [EI] (enzyme substrate inhibitor).
Ki = ([I][E])/[EI]
[E] + [I] <–> [EI]
Polarity relationship with water solubility…
As polarity increases so does water solubility.
Reasoning:
Polarity increases water solubility because polar molecules can form hydrogen bonds or dipole-dipole interactions with water, which is a highly polar solvent. These interactions allow the polar molecules to dissolve more easily by breaking into the water’s hydrogen-bonded network.
RC(=O)R ——> RCH(OH)R
What happened here?
C(=O) = carbonyl
H(OH) = hydroxyl
carbonyl to hydroxyl group.
What kind of reaction is this:
RC(=O)R ——> RCH(OH)R
Reduction reaction.
Addition of electrons and protons.
When more electronegative atoms are replaced with less electro negative atoms on a carbon, the oxidation state decreases (becomes more negative) because the carbon “gains” electrons because the pull is less intense.
What are flavins?
Group of organic compounds based on a molecular structure derived from isoalloxazine —> tricylcic ring system.
Isoalloxazine ring?
tricyclic ring
When coupling a charged particle against a concentration gradient, what happens?
Energetically costly, makes reaction less exothermic.
Pyrrole ring
1 nitrogen corner, 4 carbon corners.
Aromatic compounds
A molecule that contains a conjugated pi electron system.
Cyclic planar structure with delocalized electrons in conjugated pi bonds.
Increased stability.
What is the volume of 1 mole of gas at 0 degrees C, 1atm?
AKA STP.
How is it derived?
22.4L
22400 cm^3
Derived from PV=nRT
P = 1atm
V = Volume (L)
n = 1 mol
R = ideal gas constant .0821L
T = 273.15K
Equation that connects volume of gas, volume of 1 mole at STP, and moles.
moles = (volume of gas)/(volume of 1 mole at STP)
When will fluorescence radiation be produced, which has to be higher?
Energy of absorbed radiation or energy of fluorescence radiation?
Energy of absorbed radiation.
CD Spectroscopy
CD (circular dichroism) spectroscopy is a technique used to study the secondary structure of proteins and other chiral molecules by measuring the difference in absorption of left- and right-circularly polarized light. It helps identify structural elements such as alpha-helices, beta-sheets, and random coils by analyzing their characteristic absorbance patterns in the far-UV region (typically 180-250 nm). In the context of the MCAT, understanding CD spectroscopy is relevant for recognizing how proteins fold and how their structures relate to function.
Problem mentions where chirality arises from and mentions protein folding or amino acids, what is most likely the answer?
alpha carbon
(acarbon)
As time goes on gel is broken down, what is proteolysis?
Breaks down proteins into smaller fragments
TMPT is a transferase
Transferase: A transferase is a type of enzyme that catalyzes the transfer of a functional group (e.g., methyl, acyl, phosphate, or amino group) from one molecule (the donor) to another molecule (the acceptor).
Transferase does not result in the loss of mass when dealing with the same molecule.
All steroid hormones are derived from…
Cholesterol
Ex. of a steroid hormone: progesterone.
Chromatography
Technique used to separate, identify, and purify components of a mixture based on their differences in chemical/physical properties.
Chromatography –> elution step
Separation
Chromatography –> affinity
Identify/purify
In chromatography, what is the most important part of a compound that separates the ligand/protein?
The hydrophobic/hydrophilic regions.
How to tell if something being tested is in its native state?
If the binding affinity was similar after the reaction to what it was before the reaction.
Carboxyl Group
C(=O)OH –> acidic
More acidic than hydroxyl and carbonyl groups.
Hydroxyl group
OH
can act as a weak acid
Amine group
NH2 or NH
generally basic
Rank order acidity:
Carboxyl group
Hydroxyl group
Amine group
Carboxyl>hydroxyl>amine
Most acidic is carboxyl
Acidity and bonding
Stronger acids have weaker bonds to H+ and form more stable conjugate bases.
Imidazole
Imidazole is a heterocyclic aromatic compound with the molecular formula C3H4N2.
5 membered ring structure.
6 pi electrons
Ammonium molecular structure.
Acetate molecular structure.
Ammonium: NH4+
Acetate: CH3CO2-
Anion exchanges vs cation exchanges
Anion exchange: negatively charged.
Cation exchange: positively charged.
(Chromatography)
Imidazole in histidine side chain…
The imidazole group in histidine’s side chain is a unique functional group that imparts chemical versatility, enabling histidine to act as a proton donor, acceptor, and metal ligand.
Ketone
R(C=O)R’
Carbonyl group.
Polar, susceptible to nucleophilic attack (nucleophile donates a pair of electrons to an electrophile forming a new covalent bond).
Aldehyde
R(C=O)HR’
H bonded to carbon.
Aldehydes and ketones: Dipole-dipole interactions.
Carboxylic acid
(C=O)OH
OH bonded to carbon
Ester
R(C=O)OR’
O bonded to carbon
Hydrolysis converts esters to carboxylic acids .
Formula that combines final pressure, initial pressure, final moles of gas, and initial moles of gas.
Final pressure = initial pressure - [(final moles of gas)/(initial moles of gas)]
Reaction: 4CO(g) –> C3O2(g) + CO2(g)
What is the final pressure of reaction?
Final pressure = 1atm - 2/4 = .5 atm
Ki
Inhibitor constant
Measures how effectively inhibitor binds to an enzyme.
What is Ki in relation to a graph?
50% enzyme activity
(always)
Hill coefficient greater than 1 means…
Positive cooperativity, making when an inhibitor binds to an enzyme, others bind easier.
Reverse is true if hill coefficient is less than 1.
Diploid organism heterozygous in each of the 3 unlinked genes. How many gametes can be produced?
2^n
2^3
8
Contraction of the diaphragm = ____ intrathoracic pressure, and ____(inhalation or exhalation)
decreased, exhalation
Enzyme Reaction.
V0 =
Vmax =
Kcat =
Km =
V0 = initial velocity of enzymatic reaction (increases with more substrate).
Vmax = Max velocity of a reaction.
Kcat = Reaction turnover number (how fast an enzyme works).
Km = Rate constant of reaction (how much substrate (reactant) is needed to get the enzyme working at half of its maximum speed).
What is the resting potential of a neuron due to?
Distribution of ions across the plasma cell membrane.
Interneuron
Intercommunication point for afferent and efferent neurons in CNS.
Afferent -> To CNS.
Efferent -> Away from CNS.
Afferent vs Efferent Neurons
Afferent: Sensory, arrive at CNS
Efferent: Motor, leave CNS
What happens when blood glucose reaches highest point (peak)?
Pancreatic beta cells secrete insulin.
What happens when glucose reaches lowest point (peak)?
Pancreatic alpha cells secrete glucagon
Keq
Equilibrium constant
Keq = Products^coefficients / Reactants^coefficients
H2(g) + I2(g) <–> 2HI(g)
Keq = [HI]^2 / ([H2][I2])
What is meant when:
Keq>1
Keq<1
Most of the time…
Keq>1 - exergonic
Keq<1 - endergonic
Keq>1 -> More products than reactants.
Keq<1 -> More reactants than products.
What is meant when the reaction is fast in relation to activation energy?
Low activation energy level
How does gene passing down work for humans in relationship to mom and dad?
Sons don’t inherit dads X chromosome.
Sons: XY –> X(mom) Y(dad)
Daughters: XX –> X(mom) X(dad)
pH gradient isoelectric focusing (IEF)
A technique used to separate proteins or other charged molecules based on their isoelectric point (pI), the pH at which the molecule has no net charge.
Have to have different pI values (by a good amount)
Same thing with the method
pI
The pH at which the molecule has no net charge.
Sodium Dodecyl Sulfate-Polyacrylamide (SDS-PAGE)
Separate proteins based on their molecular weight.
Erythocytes
Red blood cells.
No nucleus, lack organelles, shape is flat disc concave center.
Fibroblasts
Connective tissue cells.
Spindle shaped, have nucleus and organelles.
Monocytes
White blood cells (leukocytes).
Have nucleus and organelles.
Electrogenic Transporter
Moves a net charge difference.
Example:
Na+ = + charge
Glucose = neutral
+ and neutral is a net charge difference.
Messengers in classical endocrine systems
Transported by blood vessels.
Chemical messengers in paracrine and autocrine (act locally, do not travel through the blood stream to act distantly).
Endocrine hormones:
Steroid hormones
Peptide/Protein hormones
Amine hormones
Amino acids structural differences.
Alanine
Leucine
Isoleucine
Glycine
Alanine - No branched side chain.
Small, simple, nonpolar.
Leucine - Gamma branched side chain
(attached to gamma carbon).
Hydrophobic, stabilizes protein cores.
Isoleucine - Beta branched side chain.
Hydrophobic, essential for protein structure.
Glycine - No branched side chain (attached to the beta carbon).
Simplest, flexible in protein structures.
B and T cells are what kind of immunity?
Adaptive immunity.
How many of which type of bond are between GC and TA?
GC : 3 hydrogen bonds.
AT/U: 2 hydrogen bonds.
Higher GC content means…
More stable duplex.
Higher melting temperature.
Increased stability.
What links DNA backbone?
Phosphodiester linkages (strong covalent bonds).
Glucose isomers:
Galactose and Fructose
Butyrate, acetate, and propionate are examples of…
Short fatty acid chains.
Higher levels of H+ means
More acidic, decrease in pH
Apoptosis
Cell death
If someone has a stroke, is apoptosis bad or good?
Apoptosis is bad, because a stroke you lose bodily function, so killing more neurons is not a good thing.
Glycoprotein
A protein backbone with one or more carbohydrate (glycan) chains covalently attached.
CAN’T PASS THROUGH CELL MEMBRANES!
G protein coupled receptor (GPCR)
Increases cAMP (used for intracellular cell signaling).
GPCRs are well known in neurotransmitters like serotonin.
Protein Kinase
Phosphorylate proteins, nothing to do with cAMP production
Tyrosine Kinase
Phosphorylation of tyrosine residues.
Ligand gated ion channel.
Mediate flow across membrane.
Hydroxylation
Adding OH group
Indole ring
C8H7N
Made of a benzene ring and a pyrrole ring.
Two rings, 3 double bonds in left, one in right.
Histidine
Contains imidazole ring and side chain.
Proline
Pyrrolidine ring: C4H9N (5 sided).
Doesn’t lead to serotonin or any neurotransmitters.
Tyrosine
Standard amino acid.
Nothing to do with neurotransmitters
When reading problems and answers, the answer must match the groups tested in the problems. So if two types of mice are tested, two types of mice will likely be answer.
ngr
What is the ratio of cationic to anionic functional groups in a protein at its pI?
1
Ionophore
Ionophores are compounds that bind to ions and facilitate their movements across membranes.
Adding an ionophore to a sodium gradient would decrease ATP because it would collapse sodium gradient (if sodium gradient (Na -NQR) is responsible for energy).
Gel Filtration Chromatography
Separates proteins based on their size.
Ion exchange chromatography
Separates proteins based on their charge.
Na+ -NQR requires
NAD+/NADH
Fluid mosaic model vs unit membrane model
Unit membrane doesn’t suggest how exchange of nutrients or waste occurs.
Oxidative Phosphorylation
Used to drive ATP synthesis. ATP synthesis is driven by ATP synthase.
(Electron Transport Chain).
Upstream vs Downstream
Upstream: Earlier in the pathway.
Downstream: Later in the pathway.
If question asks something about outcome of FNDC5.
Physical exercise –> PGG-1A expression in skeletal muscle –> FNDC5 expression –> release of irisin –>insulin effects (UCP1) –> thermogenesis (energy expenditure) –> physiological outcomes.
Answer downstream (something to do with physiological outcomes), not physical exercise.
Bacteria and viruses relation to these three topics:
Transformation
Transduction
Conjugation
Transformation: Environment —(genetic material)—> bacteria
Transduction: Viruses —(nucleic acids)—> Cells
Conjugation: Bacteria <—(nucleic acids)—> Bacteria
Richer promoter region (DNA)
Region that contains specific elements crucial for initiating and regulating transcription (at start of gene sequence).
Types of inhibitors:
Competitive
Mixed
Noncompetitive
Competitive: Prevents binding by blocking active site.
Mixed: Bind to locations other than active site.
Noncompetitive: Doesn’t bind to active site of enzyme.
Highly conserved gene:
Vital to an organisms life
Enhancer sequence
Plays critical role in increasing transcription.
Ex: SNPs in haplotypes near lactase: Enhancer genes express gene expression, without coding for the gene.
Reactions that break down things into glucose and derivatives are ___.
What enzyme is responsible for this?
Hydrolyzed (because of the glycosidic linkages)
Hydrolase
Hydrolysis is responsible foir breaking down larger molecules into smaller subunits.
Isomerase
Rearranges chemical structure/formula of a compound.
Enterocytes
Produce enzymes that digest disaccharides.
Epithelial cells
Specialized cells that line surfaces of organs and structures, forming a barrier or interface. Functions include protection, absorption, secretion, and sensation.
Colonocytes: Don’t produce enzymes
Parietal cells
Produce HCl
Hepatocytes
Liver cells, play a crucial role in metabolism, detoxification, and production of biochemicals necessary for digestion.
Functions:
Do not produce digestive enzymes.
Pyrimidine and Purine
Nitrogenous bases in DNA.
Pyrimidine: C, T, U, (C4H4N2) - 1 ring
Purine: A, G, (C5H4N4) - 2 ring (fused pyrimidine and imidazole ring).
Ka =
Ka = [H+][A-]/[HA]
Suppose a 0.1 M solution of a weak acid has a 1E-4.
At equilibrium:
[H+] = [A-] = x
[HA] = .1-x
Ka = x^2 / (.1-x)
1E-4 = x^2 / (.1-x) -> quadratic formula
Huckels rule
4n + 2 pi electron formula.
Aromatic if pi electrons fit this formula aka 6, 10, 14… etc.
- Each double bond = 2 pi electrons.
- If there is a (-) charge on the compound = 2 pi electrons.
- If nitrogen has a lone pair = 2 pi electrons.
Bonding of aldehydes vs ketones vs esters vs amides.
More reactive —–> Less reactive
Aldehydes -> Ketones -> Esters -> Amides
A molecule has a pKa of 7.0. At pH 6.0, what is the predominant form of the molecule?
A. Protonated
B. Deprotonated
C. Equally protonated and deprotonated
D. Neutral
A.
Explanation:
When pH < pKa, the molecule is mostly protonated because the environment is more acidic.
When pH > pKa, the molecule is mostly deprotonated.
Here, pH 6.0 is less than the pKa of 7.0, so the molecule remains predominantly protonated
Conjugations relation to wavelength.
More conjugated a compound is the higher the wavelength of the absorbance.
sp orbitals are less conjugated than sp2
