Wednesday, April 24, 2013• Do Now: Sequence a mRNA strand from

the DNA sequence TACCCGTTAGACGCAACCACT. Now, using the genetic code chart on page 211, determine the amino acid sequence.

• Objective: Evaluate three ways point mutations can alter genetic material.

• HW: Worksheet

Mutations

A change in the genetic material of a cell.

Good Bad Neutral

2 Types• Germ cell mutations – Occurs in

organisms germ cells.• Somatic mutations – Occurs in

organisms body cells.

Which ones can be passed to offspring?

Where Can Mutation Occur?

• Gene Mutations - Involve large segments of DNA or a single nucleotide within a codon.• Chromosome Mutations - Either

changes in the structure of a chromosome or the loss of an entire chromosome.

2 Types of Gene Mutations

Point Mutationo Substitution

Frameshift Mutationo InsertionsoDeletions

THECATSAWTHEDOG

THE CAT SAW THE DOG

Sentence = GeneWord = CodonLetter = Nucleic base

1. THE BAT SAW THE DOG

2. THE CAT SAW THE HOG 3. THE CAT SAT THE DOG

THE ATS AWT HED OG

THE CMA TSA WTH EDO G

Frameshift Mutations

THE CAT SAW THE DOGTHE ATS AWT HED OG

THE CMA TSA WTH EDO G

Frameshift Mutations1. Caused by insertion or deletions of a

nucleotide.2. Alters the triplet grouping of

nucleotides into codons.3. Shifts the reading frame so that all

nucleotides downstream will be improperly grouped.

Sickle Cell Mutation

DNA mRNA Amino AcidNormal C G T → A Glutamic Acid

T A Substitution C G A → T Valine T A

Check Point 1. Which type of mutation would have a

greater effect on the sequence of amino acids in a protein, a base pair substitution or a frameshift mutation? Explain.

2. What is the maximum number of amino acids that could be coded for by a section of mRNA with the sequence GUUCAGAACUGU.

Chromosome Mutations

• Are changes in chromosome structure.• There are four types of mutations:1.Deletion - a piece breaks off and is lost.2.Duplication - A piece is repeated.3.Inversion - A piece breaks off and reattaches in

the wrong order.4.Translocation – A piece attaches to a different

chromosome.

Karyotype

Structure of a chromosome