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MUTATIONNNNN • Although DNA proof reading can be accurate, and proofreading is done almost immediately after the addition of nucleotides sometimes DNA done goofed up. • When this happens, for example when adenine is paired with a guanine codon, sometimes an organisms DNA is damaged resulting in a small probability that genes can be altered. This is called a mutation. • Most of the time this yields no real consequence and the mutation is eventually destroyed but on rare occasions this can become lethal creating genes for things such as HIV OR CANCER
Mutation in itself happens in several different ways. • The most common is point mutation. This is where one nucleotide is either misplaced, deleted, substituted, or trans-located.
Another kind of mutation is called a silent mutation. • For a quick refresher for anyone who took bio Adenine-Thymine Guanine-Cytosine For an example of a silent mutation there’s Proline There are four ways to code for proline be it ccc, cca, ccu, or ccg. No matter which way its coded of those four proline does not change.
Mutations are classified in three different ways: • Missense- This is when a nucleotide substitution changes the amino acids being coded for • Nonsense- When a substitution results in a stop codon. Example-ACC becomes ATC which codes for UAG which is a stop codon.
The last way is called Frameshift: This is when one nucleotide is added or deleted. After the mutated pair all other pairs are thrown off this is when you get cancer or HIV. • A stop codon is a codon that essentially tells the polymerase that this is the end of the nucleotide. U and A are sometimes interchangeable since Uracil adenine and thymine all code for each other.
RNA • RNA- RNA is simply Ribo nucleic Acid. • There are there major types of RNA involved in transcribing genetic information into the language of amino acids for the cell to manufacture protiens.
There is ribosomal RNA or (rRNA)- Made in the nucleus in eukaryotic cell. (rRNA) basically binds with other protiens to help support and direct the orientation of (tRNA) and (mRNA). • Messenger RNA (mRNA)- Carries and places codons into the correct spots (most of the time) into amino acid strings. • Transfer RNA (tRNA)- Basically the same as mRNA except tRNA is only created for and then carries specific codons.