Mutation Notes: Chapter 11
Mutations notes outline Types at gene level A. Point B. Frameshift which is worse? Types at chromosome level A. Deletion B. Insertion C. Inversion D. Translocation Causes A. Random/spontaneous B. Mutagen Results -, +, no effect
Mutation: Mistake or change in DNA sequence
Types of mutations at the gene level: Point: change in a SINGLE base pair in DNA Example: ACTAGGCAC to ACTAGTCAC Like: the dog bit the CAT to the dog bit the CAR Results in a change of one codon
The change in the DNA is minor but important
The effects of point mutations mRNA Normal Protein mRNA Point mutation Protein
Frameshift mutations A single base is added or deleted from DNA which shifts the reading of codons by one base. ex. ACTAGGCAC to ACTAGAC Like: The dog bit the cat to The dob itt hec at
The results of frameshift mutations can be HUGE since every codon after the mistake is affected!
Frameshift mutations Without mutation Deletion of U mRNA Protein
Point vs. Frameshift Mutations Which type of mutation is more serious? Frameshift mutation affects every amino acid after the mutation Point mutation affects only the amino acid at the mutation
Chromosomal Alterations Chromosomal mutations--Structural changes in chromosomes Are especially common in plants. 4 main types— Deletion, insertion, inversion, translocation
Types of chromosomal mutations: Deletion: part of a chromosome left out (usually deadly) A B C E F G H A B C D E F G H Deletion
Types of chromosomal mutations: Insertion: additions to a chromosome Usually from a sister chromatid
*Genes B and C were inserted into Insertion A B C D E F G H A B C B C D E F G H Insertion *Genes B and C were inserted into the chromosome*
Types of chromosomal mutations: Inversion: chromosome part breaks off and reattaches backwards A B C D E F G H A D C B E F G H Inversion
Types of chromosomal mutations: Translocation: chromosome part breaks off and adds to another chromosome Translocation
Causes of Mutations Spontaneous/Random mutations– Some mutations just happen, (ie. mistake during DNA replication, transcription, mitosis, meiosis). These lead to evolution. Mutagen-- Any agent that causes a change in DNA Include environmental factors like chemicals and radiation Lead to birth defects if sex cells affected and cancer if body cells affected
Mutations can be: Negative: cause a structural or functional problem Positive (very rare) ex. Can make the organism faster or stronger Have no effect = silent mutation
Sometimes chromosomes fail to separate properly and result in extra or fewer chromosomes: Down syndrome- extra chromosome # 21 Turner syndrome- missing X on 23rd pair
Inversion Insertion Deletion Translocation