chapter 11.3 genetic changes. mutations sudden genetic change sudden genetic change point mutations...

Chapter Chapter 11.311.3

Genetic Genetic ChangesChanges

MutationsMutations

Sudden genetic Sudden genetic changechange Point mutationsPoint mutations Frameshift mutationFrameshift mutation Chromosomal Chromosomal

mutationmutation

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Point MutationPoint Mutation

Single base pair in DNASingle base pair in DNA Ex:Ex:

Normal – AUG AAG UUU GGCNormal – AUG AAG UUU GGC

Point - AUG AAPoint - AUG AAAA UUU GGC UUU GGC

Happens at a single point, you point Happens at a single point, you point to one thing.to one thing.

Frameshift MutationFrameshift Mutation

Addition or deletion of a single baseAddition or deletion of a single base Ex:Ex:

Normal – AUG AAG UUU GGCNormal – AUG AAG UUU GGC

Frameshift – AUG AAG UUFrameshift – AUG AAG UU GGC GGC

Think KEYBOARDThink KEYBOARD

Chromosomal MutationChromosomal Mutation

Change in chromosomesChange in chromosomes Causing Causing nondisjunctionnondisjunction (to many or (to many or

not enough parts) – failure of not enough parts) – failure of chromosomes to separate chromosomes to separate Trisomy – extra chromosomeTrisomy – extra chromosome Monosomy – missing chromosomesMonosomy – missing chromosomes Triploidy – an extra setTriploidy – an extra set

- plants mostly- plants mostly

Source: www.brooklyn.cuny.edu/.../MUT/Mut.Types.html

MutationsMutations

Some mutations can be positive – Some mutations can be positive – mutation may make an organism mutation may make an organism faster, strongerfaster, stronger

Mutations may be passed on if it Mutations may be passed on if it occurs in reproductive cells, will not occurs in reproductive cells, will not be passed on however in be passed on however in nonreproductive cells (skin, muscle, nonreproductive cells (skin, muscle, or bone.)or bone.)

MutagenMutagen

Any agent that can cause a change Any agent that can cause a change in DNAin DNA

Causes of Mutations Causes of Mutations (Mutagens)(Mutagens)

Error in DNAError in DNA Radiation – x-ray exposure, gamma Radiation – x-ray exposure, gamma

radiation, cosmic rays, UV, nuclearradiation, cosmic rays, UV, nuclear Chemicals – dioxins, asbestos, Chemicals – dioxins, asbestos,

benzene, cyanide, formaldehyde, benzene, cyanide, formaldehyde, radioactive chemicalsradioactive chemicals

Results of MutationsResults of Mutations

Birth DefectsBirth Defects CancerCancer

Repairing DNARepairing DNA

Enzymes proofread the DNA and Enzymes proofread the DNA and replace incorrect nucleotides with replace incorrect nucleotides with correct onescorrect ones