Amino acids Flashcards
How do proteins become functional?
they must fold, forming complex 3D shapes in order
What is also necessary with proteins?
post-translational modifications (PMTs)
What must happen to a protein to allow it to carry out it’s function?
it must remain stable for a period of time
What group determines the properties of the 20 amino acids?
the R group
What shape are amino acids?
Tetrahedral
How could the symmetry of amino acids be described?
chiral (asymmetrical)
Is L-Alanine or D-Alanine in all amino acids?
L-Alanine
How can you tell the difference between L-Alanine and D-Alanine?
use the CORN rule:
- place the hydrogen at the back of the molecule.
-In an anti-clockwise direction the groups read CO-R-N (For L-Alanine).
Name the 5 amino acid groups
- Hydrophobic
-Aromatic
-Polar
-Negatively charged
-Positively charged
Define amphipathic
contains both hydrophilic and hydrophobic properties
Name all of the hydrophobic amino acids
-Glycine
-Alanine
-Valine
-Leucine
-Isoleucine
-Methionine
-Proline
Describe Aromatic amino acids
-all contain a ring of delocalised electrons
-hydrophobic ring
-two are hydrophobic and the third is amphipathic
What is the most common amino acid?
Leucine
Describe Valine and it’s letter
V
-small hydrophobic amino acid often found in the hydrophobic core of globular proteins.
What amino acid is most common replacement in mutation?
Alanine
Describe methionine and it’s letter
M
- contains a sulfur
-unreactive
- often the first amino acid in an unmodified protein (as it is the initiation codon).
Describe Proline and it’s letter
P
- ring limits conformation of backbone
-can sometimes be found in cis conformation
-IMINO ACID (lacks 1 hydrogen on the amine group).
Describe phenylalanine, what is it’s letter?
F
-has phenyl group (aromatic ring).
-ring is unreactive and hydrophobic
-weakly absorbs UV light.
Describe Tyrosine and it’s letter
Y
-polar OH group, can make hydrogen bonds
-Hydrophobic ring
-overall amphipathic
-absorbs light at 280 nm
Describe Tryptophan and it’s letter
W
-largest amino acid
-weak hydrogen bonding to the NH makes it amphipathic
-strongly absorbs light at 280nm
-fluorescent
Describe polar groups
- have polar side chains or partially charged side chains
- hydrophilic and often found on the surface of proteins
Name all of the polar amino acids
- Serine
-Threonine - Cysteine
-Asparagine
-Glutamine
Describe Serine
S
- both have alcohol groups
-usually on protein surface
- Serine is smaller primary alcohol and most common replacement in mutations.
-often phosphorylated in proteins
Describe Threonine
T
- secondary alcohol
- often phosphorylated in proteins
