Mutations

Any change to the DNA Gene mutations – changes in a single gene Chromosomal mutations – changes in whole chromosomes

Gene Mutations Changes in one or a few nucleotides – POINT Mutations They occur at a single POINT in the DNA sequence. Types of Point Mutations: Substitutions – one base is changed to another Insertions/Deletions – a base is inserted or removed from the DNA sequence

POINT - Substitution DNA: TAC GCA TGG AAT mRNA: AUG CGU ACC UUA Amino acids: Met – Arg – Thr – Leu Substitution DNA: TAC GTA TGG AAT mRNA: AUG CAU ACC UUA Amino acids: Met – His – Thr – Leu

POINT - Insertion DNA: TAC GCA TGG AAT mRNA: AUG CGU ACC UUA Amino acids: Met – Arg – Thr – Leu Insertion DNA: TAT CGC ATG GAA T mRNA: AUA CGC UAC CUU A Amino acids: Ile – Ala – Tyr – Leu

Frameshift Mutations If a nucleotide is added or deleted and the entire reading of the mRNA is shifted (still reads every 3), it is a FRAMESHIFT mutation. These mutations change every amino acid that follows the mutation. HUGE effects – often can change the protein structure so much that it is unable to perform it’s normal functions.

Chromosome Mutations Chromosomal mutations – involve changes to the number or structure of chromosomes Can change the locations of genes on chromosomes Can change the number of copies of some genes

Chromosomal Mutations

Effects of Mutations Many mutations are neutral. Some mutations are harmful. can lead to genetic disorders, cancer, etc. Some mutations are beneficial. Lead to genetic variation in a species

Beneficial Mutations Polyploidy – polyploid plants receive extra copies of the chromosomes because they did not separate during meiosis 3n, 4n, even 8n! Ex. Bananas, strawberries, many citrus fruits….

Exit Slip 1.True or False - All mutations are harmful. 2. True or False - Some mutations can be beneficial. 3. Which type of mutation changes one or a few nucleotides? 4. Which type of mutation can result in drastic changes to the protein structure?