Slide 1 of 24 Copyright Pearson Prentice Hall Biology Wl-ZyRAg

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Slide 3 of 24 Copyright Pearson Prentice Hall 12-4 Mutations 12–4 Mutations

Slide 4 of 24 Copyright Pearson Prentice Hall 12-4 Mutations What are mutations?

12–4 Mutations Slide 5 of 24 Copyright Pearson Prentice Hall 12-4 Mutations Mutations are changes in the genetic material. Or alterations in the genotype that sometimes show up in the phenotype.

12–4 Mutations Slide 6 of 24 Copyright Pearson Prentice Hall Kinds of Mutations Mutations that produce changes in a single gene are known as gene mutations. Mutations that produce changes in whole chromosomes are known as chromosomal mutations.

12–4 Mutations Slide 7 of 24 Copyright Pearson Prentice Hall Kinds of Mutations Chromosomal Mutations Chromosomal mutations involve changes in the number or structure of chromosomes. Chromosomal mutations include deletions, duplications, inversions, translocations, and nondisjunctions.

12–4 Mutations Slide 8 of 24 Copyright Pearson Prentice Hall Kinds of Mutations Deletions involve the loss of part of a chromosome.

12–4 Mutations Slide 9 of 24 Copyright Pearson Prentice Hall Kinds of Mutations Duplications produce extra copies of parts of a chromosome.

12–4 Mutations Slide 10 of 24 Copyright Pearson Prentice Hall Kinds of Mutations Inversions reverse the direction of parts of chromosomes.

12–4 Mutations Slide 11 of 24 Copyright Pearson Prentice Hall Kinds of Mutations Translocations occurs when part of one chromosome breaks off and attaches to another.

12–4 Mutations Slide 12 of 24 Copyright Pearson Prentice Hall Chromosomal Disorders The most common error in meiosis occurs when homologous chromosomes fail to separate. This is known as nondisjunction, which means, “not coming apart.”

12–4 Mutations Slide 13 of 24 Copyright Pearson Prentice Hall Kinds of Mutations Gene Mutations Gene mutations involving a change in one or a few nucleotides are known as point mutations because they occur at a single point in the DNA sequence. Point mutations include substitutions, insertions, and deletions.

12–4 Mutations Slide 14 of 24 Copyright Pearson Prentice Hall Kinds of Mutations Substitutions usually affect no more than a single amino acid. One nucleotide is exchanged for another.

12–4 Mutations Slide 15 of 24 Copyright Pearson Prentice Hall Kinds of Mutations In an insertion, an extra base is inserted into a base sequence.

12–4 Mutations Slide 16 of 24 Copyright Pearson Prentice Hall Kinds of Mutations In a deletion, involves the loss of a single nucleotide. The nucleotide is deleted and the reading frame is shifted.

12–4 Mutations Slide 17 of 24 practice! Copyright Pearson Prentice Hall

12–4 Mutations Slide 18 of 24 Copyright Pearson Prentice Hall Kinds of Mutations Changes like these are called frameshift mutations. The effects of insertions or deletions are more dramatic. The addition or deletion of a nucleotide causes a shift in the grouping of nucleotides that make up codons. The result is a change in every nucleotide (and hence amino acid too) that follows the point of the gene mutation. In both, a frameshift occurs. These are the worst kind of gene mutations. KKsk

12–4 Mutations Slide 19 of 24 Copyright Pearson Prentice Hall Significance of Mutations Many mutations have little or no effect on gene expression. Some mutations are the cause of genetic disorders.

12–4 Mutations Slide 20 of 24 Copyright Pearson Prentice Hall Significance of Mutations Beneficial mutations may produce proteins with new or altered activities that can be useful. Polyploidy is the condition in which an organism has extra sets of chromosomes.

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Slide 22 of 24 Copyright Pearson Prentice Hall 12–4 A mutation in which all or part of a chromosome is lost is called a(an) a.duplication. b.deletion. c.inversion. d.point mutation.

Slide 23 of 24 Copyright Pearson Prentice Hall 12–4 A mutation that affects every amino acid following an insertion or deletion is called a(an) a.frameshift mutation. b.point mutation. c.chromosomal mutation. d.inversion.

Slide 24 of 24 Copyright Pearson Prentice Hall 12–4 A mutation in which a segment of a chromosome is repeated is called a(an) a.deletion. b.inversion. c.duplication. d.point mutation.

Slide 25 of 24 Copyright Pearson Prentice Hall 12–4 The type of point mutation that usually affects only a single amino acid is called a.a deletion. b.a frameshift mutation. c.an insertion. d.a substitution.

Slide 26 of 24 Copyright Pearson Prentice Hall 12–4 When a part of the chromosome moves to a different chromosome or two different chromosomes exchange some of their material, the mutation is called a(an) a.inversion. b.deletion. c.substitution. d.translocation.

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