Exam (elaborations)
MCAT Biochemistry complete study set with Questions and simplified Answers that are correct
- Course
- Institution
MCAT Biochemistry complete study set with Questions and simplified Answers that are correct
[Show more]
Content preview
MCAT Biochemistry complete study setwith Questions and simplified Answers
that are correct
Amino Acid - correct answer-Dipolar compound containing an amino group and a carboxyl group
Amino Group - correct answer--NH2
Carboxyl Group - correct answer--COOH
Alpha Carbon - correct answer-Central carbon atom in amino acid
Attached to amino & carboxyl groups, H atom, and side chain
Side Chain - correct answer-The variable component of an amino acid that gives the amino acid its
identity and chemical properties
also called R-group
Chiral - correct answer-A molecule with a nonsuperimposable mirror image
All amino acids (except glycine) are chiral
(S) Absolute Configuration - correct answer-All amino acids (except cysteine) have an (S) absolute
configuration
L-amino Acid - correct answer-All amino acids found in eukaryotes
Nonpolar, Nonaromatic Amino Acids - correct answer-Glycine, alanine, valine, leucine, isoleucine,
methionine, proline
Glycine - correct answer-Single H atom as side chain
Achiral
Smallest amino acid
Alanine - correct answer-Alkyl side chain (1C)
Valine - correct answer-Alkyl side chain (3C)
Leucine - correct answer-Alkyl side chain (4C)
Isoleucine - correct answer-Alkyl side chain (4C)
Methionine - correct answer-Methyl side chain (-CH3)
Contains S atom in side chain
Proline - correct answer-Cyclic amino acid
,N from amino group becomes part of side chain, forming five-part ring, limiting where is can appear on a
protein
Rigid/constraints on flexibility
Aromatic Amino Acids - correct answer-Tryptophan, phenylalanine, tyrosine
Aromaticity - correct answer-The ability of a molecule to delocalize pi electrons around a conjucated
ring, creating exceptional stability
Tryptophan - correct answer-Double-ring system
Contains N atom in one ring
Largest of aromatic amino acids
Phenylalanine - correct answer-Benzyl side chain (benzene ring + -CH2 group)
Smallest aromatic amino acid
Relatively nonpolar
Tyrosine - correct answer-Phenylalanine + -OH group
Relatively polar
Polar Amino Acids - correct answer-Serine, threonine, asparagine, glutamine, cysteine
Polarity - correct answer-An uneven sharing of electrons in a molecule, creating a slightly positive side
and a slightly negative side
Serine - correct answer--OH group in side chain
Highly polar - participate in H-bonding
Threonine - correct answer--OH group in side chain
Highly polar - participate in H-bonding
Asparagine - correct answer-Amide (-NH2) side chain
Amide N do not gain or lose protons with changes in pH - do not become charged
Glutamine - correct answer-Amide (-NH2) side chain
Amide N do not gain or lose protons with changes in pH - do not become charged
Cysteine - correct answer-Thiol (-SH) side chain - weaker than OH bond
Prone to oxidation
Negatively-charged (Acidic) Amino Acids - correct answer-Aspartic acid (aspartate), glutamic acid
(glutamate)
Aspartic Acid (Aspartate) - correct answer-Carboxylate (-COO(-)) group in side chain
,Deprotonated form of asparagine
Glutamic Acid (Glutamate) - correct answer-Carboxylate (-COO(-)) group in side chain
Deprotonated form of glutamine
Positively-charged (Basic) Amino Acids - correct answer-Lysine, arginine, histidine
Lysine - correct answer-Terminal primary amino group
Arginine - correct answer-Has 3 N atoms in side chain
Charge delocalized over all three N atoms
Histidine - correct answer-Has aromatic ring with 2 N atoms (ring is called an imidazole)
At pH 7.4, one N is protonated and the other isn't
Under acidic conditions, the 2nd N becomes protonated, making it positively charged
Hydrophobic Amino Acids - correct answer-Being repelled by water
Alanine, isoleucine, leucine, valine, phenylalanine
More likely to be found in center of protein
Nonpolar, uncharged compounds
Long alkyl chains
Hydrophilic Amino Acids - correct answer-Being attracted to water
Histidine, arginine, lysine, glutamate, aspartate, asparagine, glutamine
Polar and charged compounds and those that participate in H-bonding
Neither Really Hydrophobic/-philic - correct answer-Cysteine, threonine, serine, tyrosine, tryptophan,
proline, methionine, glycine
Amphoteric - correct answer-Ability to act as an acid or a base
Can either accept or donate a proton
For ionizable groups: tend to be protonated at low pH; deprotonated at high pH
pKa - correct answer-The pH at which half of the species are deprotonated
[HA] = [A(-)]
pKa1 - correct answer-pKa for carboxyl group
Usually around 2
pKa2 - correct answer-pKa for amino group
Usually between 9 and 10
, pKa3 - correct answer-For amino acids with ionizable side chains
Amino Acids in Acidic Conditions - correct answer-Amino acid is fully protonated
i.e. (-NH3+) and (-COOH)
Amino Acids in Neutral Conditions - correct answer-Form zwitterions
pH is near pI of amino acid
i.e. (-COO(-)) and (-NH3(+))
Zwitterion - correct answer-A molecule that contains charges, but is neutral overall
Amino Acids in Basic Conditions - correct answer-Amino acid is fully deprotonated
i.e. (-COO(-)) and (-NH2)
Isoelectric Point (pI) - correct answer-The pH at which every molecule in solution is electrically neutral
Predominantly in zwitterion form
pI(neutral amino acid) = - correct answer-(pKa(NH3+) + pKa(COOH))/2
For amino acids with neutral side chains
Have relatively neutral pI values (~6)
Buffer - correct answer-When pH of a solution is approximately = pKa of solute
The pH doesn't change very much, even when acid or base are added to solution
pI(acidic amino acid) = - correct answer-(pKa(R group) + pKa(COOH))/2
For amino acids with negatively charged side chains
Have relatively low pI values (~3.2)
pI(basic amino acid) = - correct answer-(pKa(NH3+) + pKa(R group))/2
For amino acids with positively charged side chains
Have relatively high pI values (~9.75)
Titration - correct answer-A laboratory technique in which a solution of unknown concentration is mixed
with a solution of known concentration to determine the unknown concentration
Titration Curves for Amino Acids - correct answer-Curve is nearly flat at pKa values of amino acids
Nearly vertical at pI of amino acid
Peptides - correct answer-A molecule composed of more than one amino acid
Can be subdivided into dipeptides, tripeptides, oligopeptides, and polypeptides
Dipeptide - correct answer-Two amino acid residues
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller BrianBubba. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $11.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
51292 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 15 years now