- 1 Amino acid is coded for by three bases on the mRNA (codon)
- Few amino acids only have a single codon
- The code is degenerate. This means that MOST amino acids can be coded for by multiple codons.
- Three codons act as a stop codon
- The code is non-overlapping. This means that it is read straight off, each base only read once.
- It is universal - the same codon codes for the same amino acid across organisms.
RNA
RNA is a single strand of nucleotides. It has the bases A,C,G, and U. ALL RNA has Uracil instead of Thymine.
There are two types, mRNA, and tRNA. mRNA is LINEAR. It is single stranded. It forms from DNA copying part of one of it's two strands. This then passes out of the nucleous through the nuclear pores. The mRNA associates with ribosomes, allowing it to act as the templates on which proteins are made.
tRNA is in a clover leaf shape arrangement. It is made up of about 80 nucleotides. It lines up the animo acids with the mRNA in peptide synthesis. The unpaired bases on the tRNA are complimentary to an amino acid. The anticodon is complimentary to the codon on the mRNA, thus, lining the two up in the right position.
Differences:
- DNA is a double stranded chain, mRNA + tRNA are single.
- DNA is large, mRNA is a lot smaller, and tRNA is the smallest, at only 80 bp.
- DNA is a double helix structure, mRNA is single helix, tRNA is clover shaped.
- DNA's nucleotide sugar is Deoxyribose. mRNA + tRNA have ribose.
- DNA has bases C,T,A + G. mRNA + tRNA have U,C,G, and A.
- DNA is mostly found in the nucleus. mRNA + tRNA are made in the nucleous, but found throughout the cell.
- The amount of DNA in the cells of a species is the same, this mRNA+tRNA it vareis due to factors such as metabolic activity.
- DNA is very chemically stable. mRNA is least chemically stalbe, tRNA is slightly more.
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