Mutation and Mutation and Genetic ChangeGenetic ChangeChapter 14.1Chapter 14.1

Mutations= A change in the Mutations= A change in the structure or amount of genetic structure or amount of genetic material of an organism.material of an organism.

I. Causes of MutationsI. Causes of Mutations

a. Accidental – caused during a. Accidental – caused during cell division.cell division.

b. Mutagens- caused by b. Mutagens- caused by environmental factors such environmental factors such as radiation or chemicals.as radiation or chemicals.

II. Types of MutationsII. Types of Mutations

a.a. Gene mutations-Gene mutations- Changes within Changes within the the DNA sequence. (Smaller DNA sequence. (Smaller scale)scale)

i. i. Point mutation-Point mutation- Change in Change in one one singlesingle nucleotide (letter). nucleotide (letter).

Original- THE CAT ATE RAT Original- THE CAT ATE RAT

Mutation- THE Mutation- THE TTAT ATE RATAT ATE RAT

II Types of Mutations:II Types of Mutations:

ii. ii. InsertionInsertion- - One or moreOne or more nucleotides nucleotides are are addedadded into the sequence. into the sequence.

Original- THE CAT ATE RATOriginal- THE CAT ATE RAT

Mutation- THE CAT AMutation- THE CAT AAAT ERA T…T ERA T…

iii. iii. DeletionDeletion- - One or moreOne or more nucleotides is nucleotides is removedremoved from the sequence. from the sequence.

Original- THE CAT ATE RAT Original- THE CAT ATE RAT

Mutation- T HMutation- T HCC ATA TER AT… ATA TER AT…

II Types of MutationsII Types of Mutationsv. v. Missense mutation-Missense mutation- A point A point mutation that does throw off the mutation that does throw off the amino acid sequence. amino acid sequence. vi. vi. Frameshift mutation-Frameshift mutation- A mutation A mutation that shifts the entire sequence. All that shifts the entire sequence. All insertions and deletions are insertions and deletions are considered frameshifts.considered frameshifts.vii. vii. Nonsense mutation-Nonsense mutation- When the When the mutation accidentally causes the mutation accidentally causes the code for a “stop” amino acid. This code for a “stop” amino acid. This causes the protein chain to be cut causes the protein chain to be cut short.short.

II. Types of MutationsII. Types of Mutations

II. Types of MutationsII. Types of Mutations

b. b. Chromosomal Chromosomal mutations-mutations- Mutation in Mutation in the number of or parts the number of or parts of an entire of an entire chromosome.chromosome.

i. i. DeletionDeletion- When part - When part of a chromosome or of a chromosome or gene is removed. gene is removed. Usually harmful.Usually harmful.

II. Types of MutationsII. Types of Mutations

ii. ii. DuplicationDuplication- When - When a part of a a part of a chromosome or chromosome or gene occurs twice gene occurs twice on the same on the same chromosome.chromosome.

II. Types of MutationsII. Types of Mutations

iii. iii. InversionInversion- - When two When two genes on the genes on the same same chromosome chromosome are in reverse are in reverse order.order.

II. Types of MutationsII. Types of Mutations

iv. iv. TranslocationTranslocation- - When a piece of When a piece of chromosome or chromosome or a gene ends up a gene ends up on a completely on a completely different different chromosome chromosome

II. Types of MutationsII. Types of Mutations

v. v. NondisjunctionNondisjunction- - When the When the chromosomes chromosomes do not “sort” do not “sort” correctly during correctly during meiosis. meiosis. Usually end up Usually end up with an extra with an extra chromosome.chromosome.

MutationsMutations

c. Effects of Mutationsc. Effects of Mutationsi.i.HeritabilityHeritability- Mutations are only - Mutations are only able to be inherited by offspring if able to be inherited by offspring if they affect an individual’s sex cells they affect an individual’s sex cells (gametes). (gametes). ii. ii. Cancer/tumorsCancer/tumors- Some mutations - Some mutations cause somatic cells to lose control cause somatic cells to lose control of their cell division.of their cell division.

MutationsMutations

iii. iii. New alleles-New alleles- New variations New variations of traits may occur (i.e. new of traits may occur (i.e. new coat colors, new body coat colors, new body shapes, etc.).shapes, etc.).iv. iv. Genetic disorders-Genetic disorders- May May cause physical or mental cause physical or mental disabilities.disabilities.

14.2 Regulating 14.2 Regulating Gene ExpressionGene Expression

Gene regulation in Gene regulation in prokaryotesprokaryotes