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Bell Ringer – 4/22/2014. Happy Earth Day! Bell ringers are next to the homework bin. You have 5 mins after the bell rings to complete it. . Today. Alien Activity wrap-up Lecture/notes – Mutations (13.3) Independent work – Study Guide. Data Tables for Alien Gene Analysis. Mutation.
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Bell Ringer – 4/22/2014 • Happy Earth Day! • Bell ringers are next to the homework bin. You have 5 mins after the bell rings to complete it.
Today • Alien Activity wrap-up • Lecture/notes – Mutations (13.3) • Independent work – Study Guide
Mutation In Biology, a mutationhappens whenthe DNA sequence of an individual is changed For example, if … ACG TGA CCA GGT CCG TGA became ACG TGA CCG GGT CCG TGA we would say that the A mutated to a G
What causes mutation? • Mutation can be caused by a number of things • Chemicals • Radiation • Ultraviolet light • Viruses • Random chance
Types of mutations Two categories of mutations: • Gene mutations (affect 1 gene) • Point mutations • Frameshiftmutations • Silentmutations • Chromosomal mutations • Change # or structure of whole chromosome
Point mutations • Point mutations affect just one nucleotide (one “point”) • Also called substitution mutations • For example, • THE FAT RED CAT ATE THE RAT could mutate to… • THE FAT RED HAT ATE THE RAT • Even though only one letter (nucleotide) was changed, the sentence doesn’t say the same thing it did before
Frameshift mutations • Frameshift mutations involve changing the spacing of the codons • These can either be insertion or deletion mutations • For example… • THE FAT RED CAT ATE THE RAT could mutate to • THE FAT EDC ATA TET HER AT or • THE FFA TRE DCA TAT ETH ERA T • By deleting the “R”, the entire sentence is now complete nonsense.
Silent mutations Some mutations don’t have any effect at all. For example, AUG UAC UCG GUA could mutate to AUG UAC UCU GUA Where is the mutation? Did it have an effect?
Silent mutations • One of the benefits of having multiple codons for each amino acid. • Mistakes can happen, but they won’t necessarily cause damage.
Study Guide • You have the rest of the period to work on your Chpt. 13 study guide (Due Friday) • EXPECTATIONS: • You must stay in your seat • You can work with the people at your table • Voice level should be quiet, no yelling across the room • Ask Ms. D or classmates questions now if you have any!