Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many...

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning Structural Abnormalities Deletions Translocations Inversions Duplications

Transcript of Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many...

Page 1: Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many genes Homozygosity or heterozygosity for each Consequences for gene function. Chapter

Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Structural Abnormalities

Deletions

Translocations

Inversions

Duplications

Page 2: Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many genes Homozygosity or heterozygosity for each Consequences for gene function. Chapter

Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Page 3: Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many genes Homozygosity or heterozygosity for each Consequences for gene function. Chapter

Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Deletions

Small or large

Mutation in one or many genes

Homozygosity or heterozygosity for each

Consequences for gene function

Page 4: Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many genes Homozygosity or heterozygosity for each Consequences for gene function. Chapter

Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Deletions

• Loss of chromosomal material• Large-scale deletions are lethal• Example: Cri du chat

–Deletion of short arm of chromosome 5–Affects motor and mental function– Infant cry resembles a meowing cat–Specific chromosomal break points are

associated with specific phenotypicchanges

Page 5: Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many genes Homozygosity or heterozygosity for each Consequences for gene function. Chapter

Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Cri du chat Syndrome

Fig. 6.26

Variation in phenotypeassociated with regiondeleted has been observed

Researchers have identifiedregions with genes involvedin larynx and nervoussystem development

Page 6: Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many genes Homozygosity or heterozygosity for each Consequences for gene function. Chapter

Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Cri-du chat syndromeDeletion in Chrom. 5

Prader-Willi SyndromeAngelman Syndrome

Deletions in Chromosome 15

Page 7: Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many genes Homozygosity or heterozygosity for each Consequences for gene function. Chapter

Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Structural Abnormalities

Deletions

Translocations

Inversions

Duplications

Page 8: Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many genes Homozygosity or heterozygosity for each Consequences for gene function. Chapter

Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Translocations

• Exchange of chromosomal segmentsbetween nonhomologous chromosomes

• Two major types–Reciprocal translocation

–Non-reciprocal translocation

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Types of Translocations

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Burkitt’s lymphoma

Ig- myc

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Reciprocal Translocation: yields normal and defective gamets

ABCDEKLMN

ABMNKLCDE

ParentHas complete information

ABCDEABMN

ABMNKLMN

Deletion andDuplication gametes

ABCDEKLMN

ABMNKLCDE

Normal gametes

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Types of Translocations

– Robertsonian Translocation• Centromeres from two nonhomologous

chromosomes fuse and chromosomal materialfrom the short arms is lost

• 5% of Down syndrome cases involve aRobertsonian translocation betweenchromosomes 21 and 14

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Robertsonian Translocation

A translocation betweenchromosome 14 and 21 mayproduce

• Translocation carrier

• Normal phenotype

• Translocation Down syndrome

• Lethal monosomy 21

• Lethal trisomy 14

• Lethal monosomy 14

Fig. 6.27

Page 14: Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many genes Homozygosity or heterozygosity for each Consequences for gene function. Chapter

Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Structural Abnormalities

Deletions

Translocations

Inversions

Duplications

Page 15: Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many genes Homozygosity or heterozygosity for each Consequences for gene function. Chapter

Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

New context Antennapedia

•Antp protein is made in antennal primordial cells, where the WT Antp does not express

•Legs grow out in Antp mutant in place of antenna

•Inversions reorganize DNA sequences

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Wild-type head

Antp required for identity of T2 (Wings and legs)

Expression of Antp in head results in legs forming in place of antennae

Antp expressed in head

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Structural Abnormalities

Deletions

Translocations

Inversions

Duplications

Page 19: Structural Abnormalities - Brandeis Life Sci Powerpoints/chapter… · Mutation in one or many genes Homozygosity or heterozygosity for each Consequences for gene function. Chapter

Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Evolution of genes/gene families

myoglobin

α familyß family

Hemoglobin family

gene duplicationdivergence

gene duplicationdivergence

(~ 700 million years ago)

(~ 450 million years ago)

Primordial geneEncodes O2 carrier protein

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Other Chromosomal Abnormalities

• Uniparental disomy–Both copies of a chromosome are

inherited from a single parent–Due to error in cell division–Examples

• Females affected with rare X-linked disorders• Prader-Willi and Angelman syndromes

• Fragile sites–Over 100 have been identified

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Fig. 6.29

Uniparental Disomy

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Chapter 6 Human Heredity by Michael Cummings ©2006 Brooks/Cole-Thomson Learning

Fragile Siteson the Human X Chromosome

Fig. 6.30