What ’ s the Purpose of All This DNA Stuff? *Sequence of nitrogen bases along the DNA strand (genes) code for an amino acid sequence (which make up proteins) - Proteins are responsible for the traits organisms possess.

Mutations -A change in the genetic information

Kinds of Mutations Point mutation: gene mutation involving a change in 1 or a few nucleotides Substitutions = 1 base is changed for another Ex: G to C or A to G insertions = 1 base is inserted in the sequence CGTACT - CGTAACT

deletion = 1 base is deleted from the sequence CGTACT - CTACT -Substitutions will usually only affect 1 amino acid -Insertions or deletions will change the reading frame of mRNA (how we decipher the mRNA into AA’s)

Frameshift mutation: mutations that shift the reading frame of the genetic message - Will change the amino acid sequence of every AA that follows the mutation = protein probably won’t function correctly Insertion and deletion

Significance of Mutations -Some mutations do not have any affect (silent mutation) - some change function of proteins produced; changing biological activities of an organism - some are beneficial and help an organism survive in a changing environment

-Mutations in body cells won’t be passed on to offspring - mutations in gametes will Polyploidy: condition in which an organism has extra sets of chromosomes - Can make some organisms stronger & larger

Chromosomal Mutations 4 Types: Deletion = loss of part or all of a chromosome Duplication = produce extra copies of parts of a chromosome Inversion = reverse the direction of parts of a chromosome

4. Translocation = part of a chromosome breaks off and reattaches to another

Assignment: Work together with a partner (or by yourself) and analyze the DNA strands on the handout. You will decided what kind of mutation has occurred.