Amino Acids Flashcards
What are the structures of typical amino acids found in proteins?
Carbon atom (a-carbon atom) covalently linked to:
(a) amino group (-NH2)
(b) carboxyl group (-COOH)
(c) variable side chain (R-group)
(d) hydrogen (-H)
How many amino acids are there?
20
Amino acids consist of what 4 groups connected to the central alpha carbon?
(a) amino group (-NH2)
(b) carboxyl group (-COOH)
(c) variable side chain (R-group)
(d) hydrogen (-H)
At physiological pH, the amino group is _______
Protonated. (-NH3+)
At physiological pH, the carboxyl group is ______
Unprotonated. (-COOH-)
What makes up a tetrahedral amino acid structure?
- 4 equilateral triangles
- Alpha carbon in the middle
- 4 vertices (amino group, carboxyl group, R side chain, alpha carbon)
How many Nonpolar/Hydrophobic Amino Acids are there?
8
What are the 8 nonpolar/hydrophobic amino acids?
Alanine (Ala)
Valine (Val)
Leucine (Leu)
Isoleucine (Ile)
Proline (Pro)
Methionine (Met)
Phenylalanine (Phe)
Tryptophan (Trp)
Alaska Values Leuding Illegal Pro Meth Phetanyl Trp
ALA
Alanine
VAL
Valine
LEU
Leucine
ILE
Isoleucine
PRO
Proline
MET
Methionine
PHE
Phenylalanine
TRP
Tryptophan
A
Alanine
V
Valine
L
Leucine
I
Isoleucine
P
Proline
M
Methionine
F
Phenylalanine
W
Tryptophan
Why are amino acids nonpolar/hydrophobic?
They are made of just carbons & hydrogens. Either in forms of chain, cyclic structures, or linear
Alanine (Ala, A) R chain
alkyl chain R group
(linear chain of carbon & hydrogens)
(short with branches)
Valine (Val, V) R chain
alkyl chain R group
(linear chain of carbon & hydrogens)
(short with branches)
Leucine (Leu, L) R chain
alkyl chain R group
(linear chain of carbon & hydrogens)
(short with branches)
Isoleucine (Ile, I) R chain
alkyl chain R group
(linear chain of carbon & hydrogens)
(short with branches)
Proline (Pro, P) R chain
unusual cyclic structure
Methionine (Met,M) R chain
sulfur containing
Phenylalanine (Phe, F) R chain
aromatic
(6 sided ring structure)
Tryptophan (Trp, W) R chain
aromatic
(6 sided ring structure)
What makes prolines structure unique?
It has two linkage points to the central carbon from the R-Side chain
How many polar/hydrophilic amino acids are there?
8
What are the polar/hydrophilic amino acids?
Asparagine (Asn)
Glycine (Gly)
Histidine (His)
Glutamine (Gln)
Threonine (Thr)
Serine (Ser)
Tyrosine (Tyr)
Cysteine (Cys)
As Gly hits glutes, threo seriously types cysts
Gly
Glycine
Ser
Serine
Threonine
Thr
Tyr
Tyrosine
Asn
Asparagine
Gln
Glutamine
His
Hisidine
G
Glycine
S
Serine
T
Threonine
Y
Tyrosine
C
Cysteine
N
Asparagine
Q
Glutamine
H
Histidine
Glycine (Gly, G) R chain
Simplest R group (H)
* Doesn’t fit with polar or nonpolar *
Threonine (Thr, T) R chain
Hydroxyl (OH) at end of R side chain
Branched
Serine (Ser, S) R chain
Hydroxyl (OH) at end of R side chain
Linear
Tyrosine (Tyr, Y) R chain
Hydroxyl (OH) at end of R side chain
Ring
Cysteine (Cys, C)
Sulfur containing (SH)
Asparagine (Asn, N)
Amide in R group (NH2)
Linear
Glutamine (Gln, Q)
Amide in R group (NH2)
Branched
Histidine (His, H)
Amide in R group (NH2)
Ring
What are the R side chains of polar amino acids?
-OH -NH or -SH
What are the R side chains of nonpolar amino acids?
-CH2 -CH3 - S
How many acidic amino acids are there?
2
What are the acidic amino acids?
Aspartic Acid (Asp, D)
Glutamic Acid (Glu, E)
Aspartic acid (Asp, D) R chain
carboxyl (COOH) in R group
Glutamic Acid (Glu, E)
carboxyl (COOH) in R group
What does acidic amino acid mean?
Net negative charge at PH 7.0
How many basic amino acids are there?
2
What are the basic amino acids?
Lysine (Lys,K)
Arginine (Arg, R)
Lysine (Lys,K) R chain
positively charged nitrogen-containing
Arginine (Arg, R) R chain
positively charged nitrogen-containing
What does basic amino acid mean?
net positive charge at neutral PH
What are the 3 groups in the charged amino acids?
- COO-
- NH3+
= NH2+
Hydroxylysine is a modified ____ found in ____
lysine, collagen
Acetyllysine is a modified ____ found in _____
lysine, histone proteins
Thyroxine has added ____ and lost other atoms
4 iodines
Carboxyglutamic acid is modified ____ involved in ____
glutamic acids, blood clotting
Carboxyglutamic acid has two added ___
carboxyl groups
Thyroxine makes ____
thyroid hormones
Acetyllysine has an added ___ linked through the amino acid
acetyl
Acetyllysin allowed for ___ and the modification is later removed to allow histones to rebind to DNA
DNA seperation
Acetyllysin ____ lysine to allow for DNA strand seperation
neutralized
The cationic form of an amino acid is at ___ pH
low
What group is neutral when the amino acid is in cationic form?
carboxyl
What group is positively charged when the amino acid is in cationic form?
amino
What is released when going from cationic form to zwitterion form (neutral)?
H+
What is negatively charged when the amino acid is in neutral/zwitterion form?
carboxyl
What group is positively charged when the amino acid is in neutral/zwitterion form?
amino
What is lost when going from zwitterion form to anionic form?
H+
What group is negatively charged in anionic form?
carboxyl
What group is neutral in anionic form?
amino
Charge of cationic form
+1
pH of cationic form
pH = 1
Charge of zwitterion form
0
pH of zwitterion form
pH = 7
Charge of anionic form
-1
pH of anionic form
pH = 13
The 1 + and 1 - charged groups on the zwitterion atom makes it ______
neutral
How is a peptide bond formed?
Reaction of the
1. carboxyl group of one amino acid
&
2. amino group of another
Reaction of forming a peptide bond results in the ___ of a water molecule
water
CO-NH is a ____ bond
peptide/amide
Formation of a peptide bond
- Two amino acids
- Removal of a water molecule
- Formation of the CO-NH
What are the two terminal ends of peptide bonds?
- N (amino end)
- C (carboxyl end)
What are two reactions of amino acids
- peptide bond
- disulfide bridge
Disulfide bridges involve the _ __ ____ of an amino acid
R side chain
What does the formation of a disulfide bridge hekp with?
Folding of protein chains
Forms loops
Stabilizes the 3D protein structure
What configuration are proteins naturally in?
L
Are disulfide bridges essential?
NO
Lab technique of seperating amino acids/proteins
Ion exchange chromatography
What amino acid can form a disulfide bridge?
Cysteine
Bead used in ion exchange chromatography is ____
negatively charged
