Amino Acids

Amino acids are the building blocks of proteins. They are coded from the genetic codons, also called nucleotides or bases. There are four nucleotides in the DNA code. They are:

Adenine bonds only to Thymine because each of them must form exactly two bonds. Guanine bonds only to Cytosine because each of them forms exactly three bonds. After transcription of the DNA, RNA is used and Thymine is replaced by Uracil (U) in all forms of RNA. The codons use the following code to create the amino acids. There are four base pairs and they code into triplet codes. Each triplet code codes to one and only one protein. With 4 bases in combinations of 3 possible codes this is 4 to the 3rd power or 81 possible codes. However, several codes code to the same amino acid. There are a total of 22 unique codes and 21 amino acids, the other code is a stop code. The following table shows these codes.

UUU

UUC

Phenylalanine

UUA

UUG

Leucine

UCU

UCC

UCA

UCG

Serine1

UAU

UAC

Tyrosine

UAA

UAG

Stop codes

UGU

UGC

Cysteine
UGA Stop code
UGG Tryptophan
 

CUU

CUC

CUA

CUG

Leucine

CCU

CCC

CCA

CCG

Proline

CAU

CAC

Histine

CAA

CAG

Glutamine

CGU

CGC

CGA

CGG

Arginine2
 

AUU

AUC

AUA

Isoleucine
AUG Methionine

ACU

ACC

ACA

ACG

Threonine

AAU

AAC

Asparagine

AAA

AAG

Lysine

AGU

AGC

Serine1

AGA

AGG

Arginine2
 

GUU

GUC

GUA

GUG

Valine

GCU

GCC

GCA

GCG

Alanine

GAU

GAC

Aspartic Acid

GAA

GAG

Glutamic Acid

GGU

GGC

GGA

GGG

Glycine

With these amino acids the body can code any protein it needs. Of these amino acids, eight are considered essential because the body, by itself, cannot make enough of them. Essential then means that we must get these amino acids in our diet or our body has to make to without enough. This insufficiency can be a serious problem and can cause problems in our bodies.