MCAT: BIOCHEMISTRY 2024/2025 EXAM WITH FULLY _ _ _ _ _ _ _
SOLVED AND UPDATED SCORE. _ _ _
amino acid -- Correct Answer ✔✔ molecules that contain:
_ _ _ _ _ _ _ _
1. an amino group (-NH2)
_ _ _ _ _
2. carboxyl group (-COOH)
_ _ _ _
3. R group/side chain - determines the chemical properties
_ _ _ _ _ _ _ _ _
4. Hydrogen atom (-H)
_ _ _ _
main focus is on alpha aa's
_ _ _ _ _ _
- not every amino acid is an alpha aa (GABA)
_ _ _ _ _ _ _ _ _ _
- not every amino acid is coded for a codon
_ _ _ _ _ _ _ _ _ _
- some aa's are converted to non codon coded aa for specific reasons
_ _ _ _ _ _ _ _ _ _ _ _ _
- in eukaryotes they are all L configuration
_ _ _ _ _ _ _
alpha amino acid -- Correct Answer ✔✔ aa that the amino group and the carboxyl group
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _
are attached to the same carbon (alpha carbon of the carboxylic acid)
_ _ _ _ _ _ _ _ _ _ _ _ _
alpha carbon is chiral (besides glycine)
_ _ _ _ _ _
- optically active
_ _ _
- in eukaryotes they are all L configuration
_ _ _ _ _ _ _
R group -- Correct Answer ✔✔ side group of the amino acid
_ _ _ _ _ _ _ _ _ _ _ _
every amino acid has a different one
_ _ _ _ _ _ _
determines the properties of the amino acids and thus their functions
_ _ _ _ _ _ _ _ _ _
GABA -- Correct Answer ✔✔ gamma aminobutyric acid
_ _ _ _ _ _ _ _
amino group and carboxyl group are not on the same carbon
_ _ _ _ _ _ _ _ _ _ _
,amino group is on the gamma carbon from the carbonyl
_ _ _ _ _ _ _ _ _
proteinogenic amino acids -- Correct Answer ✔✔ 20 alpha amino acids _ _ _ _ _ _ _ _ _ _ _
amino acids that are encoded by the human genetic code through codons
_ _ _ _ _ _ _ _ _ _ _ _
since they are all chiral at the alpha carbon (besides glycine)
_ _ _ _ _ _ _ _ _ _ _
- L CONFIGURATION
_ _ _
have at least two group that can be protonated/deprotonated
_ _ _ _ _ _ _ _ _
- two (maybe three) pka's
_ _ _ _
chiral amino acids -- Correct Answer ✔✔ the alpha carbon in alpha aa's
_ _ _ _ _ _ _ _ _ _ _ _ _
optically active _ _
has four different groups attached to it
_ _ _ _ _ _ _
exception - glycine (has two H's) _ _ _ _ _ _
L configuration - goes to the S absolute configuration
_ _ _ _ _ _ _ _
G -- Correct Answer ✔✔ Glycine
_ _ _ _ _ _
*GLY* _
R group - H
_ _ _
ACHIRAL (not L or D) _ _ _ _ _
smallest amino acid _ _ _
*nonpolar, non-aromatic R group* _ _ _
hydrophobic - interior of proteins _ _ _ _
Cahn Ingold Prelog System -- Correct Answer ✔✔ L amino acids are S configuration
_ _ _ _ _ _ _ _ _ _ _ _ _ _
AMINO GROUP IS TO THE LEFT in a fisher projection_ _ _ _ _ _ _ _ _
C -- Correct Answer ✔✔ Cysteine
_ _ _ _ _ _
*CYS*
R group = -CH2SH
_ _ _ _
*polar side chain* _ _ _
,has a *thiol* group
_ _ _ _
-since sulfur is larger and less electronegative than oxygen SH bond is weaker than an
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _
OH bon _ _
-makes SH prone to OXIDATION reaction _ _ _ _ _ _
L amino acid
_ _ _
*R absolute configuration *
_ _ _
A -- Correct Answer ✔✔ Alanine
_ _ _ _ _ _
*ALA*
R Group = -CH3
_ _ _
*nonpolar, non-aromatic R group* _ _ _
alkyl side chain with one carbon makes it nonpolar
_ _ _ _ _ _ _ _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
hydrophobic - interior of proteins _ _ _ _
R -- Correct Answer ✔✔ Arginine
_ _ _ _ _ _
*ARG* _
R group = -CH2CH2CH2-NH-C(=NH)NH2
_ _ _
*positive/basic Side Chain* _ _ _
-three nitrogens in its side chain _ _ _ _ _ _
*positive charge is delocalized over all three nitrogen atoms*
_ _ _ _ _ _ _ _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
hydrophilic - surface of proteins _ _ _ _
N -- Correct Answer ✔✔ Asparagine
_ _ _ _ _ _
*ASN*
R group = -CH2C(O)NH2
_ _ _ _
*polar side chain* _ _ _
*amide side chain* _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
hydrophilic - surface of proteins _ _ _ _
, D -- Correct Answer ✔✔ Aspartic Acid/ ASPARTATE
_ _ _ _ _ _ _ _
*ASP*
R group = -CH2C(O)OH
_ _ _ _
*Negative/Acidic Side Chain* _ _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
hydrophilic - surface of proteins _ _ _ _
E -- Correct Answer ✔✔ Glutamic Acid/ GLUTAMATE
_ _ _ _ _ _ _ _
*GLU*
R group = -CH2CH2C(O)OH
_ _ _
*Negative/Acidic Side Chain* _ _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
hydrophilic - surface of proteins _ _ _ _
Q -- Correct Answer ✔✔ Glutamine
_ _ _ _ _ _
*GLN* _
R group = -CH2CH2C(O)NH2
_ _ _
*polar side chain* _ _ _
*amide side chain* _ _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
hydrophilic - surface of proteins _ _ _ _
H -- Correct Answer ✔✔ Histidine
_ _ _ _ _ _
*HIS*
R group = imidazole
_ _ _
*positive/basic Side Chain* _ _ _
-aromatic ring with two nitrogens_ _ _ _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
SOLVED AND UPDATED SCORE. _ _ _
amino acid -- Correct Answer ✔✔ molecules that contain:
_ _ _ _ _ _ _ _
1. an amino group (-NH2)
_ _ _ _ _
2. carboxyl group (-COOH)
_ _ _ _
3. R group/side chain - determines the chemical properties
_ _ _ _ _ _ _ _ _
4. Hydrogen atom (-H)
_ _ _ _
main focus is on alpha aa's
_ _ _ _ _ _
- not every amino acid is an alpha aa (GABA)
_ _ _ _ _ _ _ _ _ _
- not every amino acid is coded for a codon
_ _ _ _ _ _ _ _ _ _
- some aa's are converted to non codon coded aa for specific reasons
_ _ _ _ _ _ _ _ _ _ _ _ _
- in eukaryotes they are all L configuration
_ _ _ _ _ _ _
alpha amino acid -- Correct Answer ✔✔ aa that the amino group and the carboxyl group
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _
are attached to the same carbon (alpha carbon of the carboxylic acid)
_ _ _ _ _ _ _ _ _ _ _ _ _
alpha carbon is chiral (besides glycine)
_ _ _ _ _ _
- optically active
_ _ _
- in eukaryotes they are all L configuration
_ _ _ _ _ _ _
R group -- Correct Answer ✔✔ side group of the amino acid
_ _ _ _ _ _ _ _ _ _ _ _
every amino acid has a different one
_ _ _ _ _ _ _
determines the properties of the amino acids and thus their functions
_ _ _ _ _ _ _ _ _ _
GABA -- Correct Answer ✔✔ gamma aminobutyric acid
_ _ _ _ _ _ _ _
amino group and carboxyl group are not on the same carbon
_ _ _ _ _ _ _ _ _ _ _
,amino group is on the gamma carbon from the carbonyl
_ _ _ _ _ _ _ _ _
proteinogenic amino acids -- Correct Answer ✔✔ 20 alpha amino acids _ _ _ _ _ _ _ _ _ _ _
amino acids that are encoded by the human genetic code through codons
_ _ _ _ _ _ _ _ _ _ _ _
since they are all chiral at the alpha carbon (besides glycine)
_ _ _ _ _ _ _ _ _ _ _
- L CONFIGURATION
_ _ _
have at least two group that can be protonated/deprotonated
_ _ _ _ _ _ _ _ _
- two (maybe three) pka's
_ _ _ _
chiral amino acids -- Correct Answer ✔✔ the alpha carbon in alpha aa's
_ _ _ _ _ _ _ _ _ _ _ _ _
optically active _ _
has four different groups attached to it
_ _ _ _ _ _ _
exception - glycine (has two H's) _ _ _ _ _ _
L configuration - goes to the S absolute configuration
_ _ _ _ _ _ _ _
G -- Correct Answer ✔✔ Glycine
_ _ _ _ _ _
*GLY* _
R group - H
_ _ _
ACHIRAL (not L or D) _ _ _ _ _
smallest amino acid _ _ _
*nonpolar, non-aromatic R group* _ _ _
hydrophobic - interior of proteins _ _ _ _
Cahn Ingold Prelog System -- Correct Answer ✔✔ L amino acids are S configuration
_ _ _ _ _ _ _ _ _ _ _ _ _ _
AMINO GROUP IS TO THE LEFT in a fisher projection_ _ _ _ _ _ _ _ _
C -- Correct Answer ✔✔ Cysteine
_ _ _ _ _ _
*CYS*
R group = -CH2SH
_ _ _ _
*polar side chain* _ _ _
,has a *thiol* group
_ _ _ _
-since sulfur is larger and less electronegative than oxygen SH bond is weaker than an
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _
OH bon _ _
-makes SH prone to OXIDATION reaction _ _ _ _ _ _
L amino acid
_ _ _
*R absolute configuration *
_ _ _
A -- Correct Answer ✔✔ Alanine
_ _ _ _ _ _
*ALA*
R Group = -CH3
_ _ _
*nonpolar, non-aromatic R group* _ _ _
alkyl side chain with one carbon makes it nonpolar
_ _ _ _ _ _ _ _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
hydrophobic - interior of proteins _ _ _ _
R -- Correct Answer ✔✔ Arginine
_ _ _ _ _ _
*ARG* _
R group = -CH2CH2CH2-NH-C(=NH)NH2
_ _ _
*positive/basic Side Chain* _ _ _
-three nitrogens in its side chain _ _ _ _ _ _
*positive charge is delocalized over all three nitrogen atoms*
_ _ _ _ _ _ _ _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
hydrophilic - surface of proteins _ _ _ _
N -- Correct Answer ✔✔ Asparagine
_ _ _ _ _ _
*ASN*
R group = -CH2C(O)NH2
_ _ _ _
*polar side chain* _ _ _
*amide side chain* _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
hydrophilic - surface of proteins _ _ _ _
, D -- Correct Answer ✔✔ Aspartic Acid/ ASPARTATE
_ _ _ _ _ _ _ _
*ASP*
R group = -CH2C(O)OH
_ _ _ _
*Negative/Acidic Side Chain* _ _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
hydrophilic - surface of proteins _ _ _ _
E -- Correct Answer ✔✔ Glutamic Acid/ GLUTAMATE
_ _ _ _ _ _ _ _
*GLU*
R group = -CH2CH2C(O)OH
_ _ _
*Negative/Acidic Side Chain* _ _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
hydrophilic - surface of proteins _ _ _ _
Q -- Correct Answer ✔✔ Glutamine
_ _ _ _ _ _
*GLN* _
R group = -CH2CH2C(O)NH2
_ _ _
*polar side chain* _ _ _
*amide side chain* _ _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
hydrophilic - surface of proteins _ _ _ _
H -- Correct Answer ✔✔ Histidine
_ _ _ _ _ _
*HIS*
R group = imidazole
_ _ _
*positive/basic Side Chain* _ _ _
-aromatic ring with two nitrogens_ _ _ _ _
L amino acid
_ _ _
S absolute Configuration
_ _ _
