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 MutationsPoint 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 Ginsertions = 1 base is inserted in the sequence

CGTACT - CGTAACT

deletion = 1 base is deleted from the sequenceCGTACT - 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 Mutations4 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.