MUTATIONS & HUMAN GENETICS

Chapter 11.3, Chapter 12

Mutations (11.3)

• Mutation = change in DNA sequence• Mutations can be caused by errors in replication,

transcription, translation, cell division, or external agents

• Mutations in reproductive cells can affect potential offspring (ex: inheritable genetic disorders)

• Mutations in body cells do not get passed onto offspring (ex: if an individual develops skin cancer)

Types of Mutations

• Point Mutations = a change in a single DNA base pair

• Frameshift Mutations = a single base is added or deleted from DNA

• DeletionMutations that result in missing DNA are called deletions.

• Insertion Mutations that result in the addition of extra DNA are called insertions.

• The insertion or deletion of a single base causes a frameshift mutation.

• Insertion or deletion of 3 nucleotides (bases) does not cause a frameshift mutation but results in an extra or missing amino acid.

• Chromosomal Mutations = missing or extra pieces of chromosomes, switched pieces, extra chromosomes– occurs frequently in plants, “super sized

strawberries”– Few C.M.’s get passed onto offspring because the

zygote dies or the mature offspring cannot reproduce

Cause & Repair

• Some mutations are spontaneous• Mutagen = any agent that causes DNA change

(ex: harmful chemicals, radiation)• Cells have repair mechanisms and special

enzymes that can fix incorrect DNA