Amino Acids Flashcards
Name the 3 groups making up an amino acid
Side chain (R)
Primary amine (NH3+)
Carboxylate (COO-)
Amino acid has no net charge due to opposite charges, what is this called
Zwitterion
Name the ends of the amino acids
N terminus. And C terminus
What is the carbon in the middle of an amino acid called
Alpha carbon
What is the importance of the position of amino acids (CORN)
To be used in a protein they all need to be the L isomer Eg L alanine instead of D isomer
This follows the CO R N rule
Peptide bonds are rigid due to partial double bonds. What gives it its double bond
The carbonyl oxygen gives the double bond between N = C. And the single bond swaps to the carbonyl oxygen
Bonds can sometimes rotate in amino acids. The trans bond is the common one with the hydrogen on bottom of N, what is it called when hydrogen swaps to the top of nitrogen to be aligned with oxygen ?
Cis bond
Why is the alpha carbon called asymmetric?
Different elements on each side of it. Eg side chain, NH3, coo
Give the name of the 4 hydrophobic amino acids (due to hydrocarbon chains)
Valine - val V
Leucine - Leu L
Isoleucine - IIE I
Methionine - Met M
3 aromatic amino acids
Phenylaline - Phe - F
Tryptophan - trp - W
Tyrosine - Tyr - Y
Why is proline amino acid special?
It’s side chain joins back to the primary amine
Give the codes for asparagine amino acid
Asn
N
What is the one letter code for glutamine
Q
Name the 2 negatively charged amino acids
(Due to the O-) and carboxylate chain
Aspartate - Asp - D
Glutamate - Glu - E
Name the 2 positive amino acids (due to NH3+) side chains
Lysine - K - Lys
Arginine - Arg - R
What makes hydrophobic amino acids hydrophobic? (Made of hydrocarbon chains)
Electro negativity is the same in carbon and hydrogen - ability to attract electrons
Electrons spread which gives them no overall charge (non polar) - can’t mix in water
Aspartate and glutamate are negative, what gives them negative charge when in water
The carboxylate OH loses the H proton leaving it with just O-
What happens to lysine and arginine to give them a positive charge
They start off as NH2 but a proton H associates in water and becomes NH3+
Why is glycine not an L or D isomer
The side chain is H, this is the same as another chain meaning 2 same chains = no isomer
Why is glycine in flexible regions of proteins
Because of the small side chain
Cysteine contains SH which is unique. Why is this side chain so important for proteins
When SH oxidised. Sulfur makes cross links in proteins via DISULFIDE BONDS- needed in extra cellular proteins
Also can bind to metals like ZN++ to form a protein metal binding site
Why is SH called a Thiol group?
Because the H is lost so easily. Ie allowing disulfide bonds
Why is histidine partially positive charged
It is ionising like the others Eg glutamate- this is because it can accept or donate a positive proton.
Can histidine bind to metals like ZN++?
Yes if there are 2 histidine in the case of ZN
Why are aromatic amino acids hydrophobic
CH rings, electro negativity is equal which means floating electrons. No charge
