Genetic Mutations

Amino Acid Purpose Each group of 3 bases on a DNA strand signifies a certain Amino Acid to be created. Ex: AAC = Asparagine A protein is produced by the ribosomes based on the sequence of amino acids. The protein is then released into the body to do it’s job.

Types of Mutations Mutations are caused by a change in the DNA sequence due to a mistake when copying when cells reproduce. There are 4 different types of mutations Substitution Insertion Deletion Frameshift

Substitution Substitution is a mutation that exchanges one base for another. CTGGAG becomes CTGGCG Effects: 1-This can cause a small change in the protein produces, causing disorders such as sickle-cell anemia. 2-Some changes to a codon that encodes the same amino acid – causing no change in the protein. These are called “silent mutations” 3- If the substitution creates a “stop” codon, this can cause an imcomplete protein, where most likely the protein won’t function at all.

Insertion Mutations in which extra base pairs are inserted into a new place in the DNA. Ex: CTGGAG becomes CTGGTGGAG

Deletion Deletions are mutations in which a section of DNA is lost, or deleted Ex: CTGGAG - becomes CTAG

Frameshift Since protein-coding dNA is divided into codons three bases long, insertions and deletions can alter a gene so that it’s message is no longer correctly parsed. For example in the sentence The Fat Cat Sat, each word represents a codon. If the first letter is deleted, the sentence won’t make sense. Hef Atc Ats At This causes DNA codons to be parsed incorrectly. This generates truncated proteins that are useless.

Mutation Causes DNA fails to copy accurately External Influences – such as specific chemicals or radiation. These can cause the DNA to break down. When the cell repairs the DNA, it might not do a perfect job of the repair, causing a difference in DNA

Effects of Mutations Somatic Mutations occur in non-reproductive cells and can NOT be passed onto offspring. Germ-line mutations occur in reproductive cells (sperm and egg) and are passed on to offspring.

Germ-line mutations can have a range of effects: No change occurs in phenotype: If a mutation occurs in a stretch of DNA with no function, or if the mutation does not affect the amino acid produced. Small change occurs in physical characteristic – a single mutation that might cause ears to bend slightly, etc. Big change in physical characteristic – such as pesticide resistant insects, heart formed improperly, etc. If the mutation causes the death of an organims, it is called lethal mutation.