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MUTATIONS & HUMAN GENETICS Chapter 11.3, Chapter 12.

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Presentation on theme: "MUTATIONS & HUMAN GENETICS Chapter 11.3, Chapter 12."— Presentation transcript:

1 MUTATIONS & HUMAN GENETICS Chapter 11.3, Chapter 12

2 Mutations (11.3)  Mutation = change in DNA sequence  Mutations can be caused by errors in replication, transcription, translation, cell division, or external agents.  Mutations in reproductive cells can affect potential offspring (ex: inheritable genetic disorders)  Mutations in body cells do not get passed onto offspring (ex: if an individual develops skin cancer)

3 MUTATIONS  THE DOG RAN ALL DAY becomes THE DOG ANA LLD AY THE DOG ANA LLD AY or or  THE DOG RAN ALL DAY becomes THE DOG SRA NAL LDA Y THE DOG SRA NAL LDA Y  What happened in each sentence?

4 Types of Mutations Types of Mutations Can alter the genetic code causing changes to amino acids and then protein produced.  Frameshift  Frameshift - moves reading frame to the left or right.  Deletion = a base is deleted  Insertion = a base is added

5 Mutations  THE DOG RAN ALL DAY becomes THE DOG RUN ALL DAY THE DOG RUN ALL DAY or or  THE DOG RAN ALL DAY becomes THE DOG RAN THE DOG RAN or or

6 Point Mutation/Substitution – One base is substituted in place of another possibly altering amino acids (a.a.) produced  Missense Mutation – changes a.a.  Silent Mutation – doesn’t change a.a.  Nonsense Mutation – changes a.a. to a stop codon

7  http://highered.mcgraw- hill.com/sites/0072556781/student_view0 /chapter11/animation_quiz_4.html http://highered.mcgraw- hill.com/sites/0072556781/student_view0 /chapter11/animation_quiz_4.html http://highered.mcgraw- hill.com/sites/0072556781/student_view0 /chapter11/animation_quiz_4.html

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10  Non Coding Chromosomal Mutations missing or extra pieces of chromosomes, switched pieces, extra chromosomes (nondisjunction)  occurs frequently in plants, “super sized strawberries”  Few chromosomal mutations get passed onto offspring because…  The zygote dies or the mature offspring cannot reproduce and is sterile

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12  Mutation of genetic material will affect the proteins produced

13 Sickle Cell – result from the change in one base on Chromosome 11.

14 Cause & Repair  Some mutations are spontaneous others can be the result of long term  Mutagen = any agent that causes DNA change (ex: harmful chemicals, radiation)  Cells have repair mechanisms and special enzymes that can fix incorrect DNA.

15 HUMAN TRAITS Chapter 12, Section 1

16 Pedigree  Pedigree = map of inheritance of genetic traits from generation to generation

17 Karyotype  Chromosomes come in pairs, inherited from parents  Karyotype = a chart of chromosome pairs, can be used to visualize chromosomal abnormalities  Humans have 23 pairs of chromosomes, 46 total chromosomes

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19  Autosomes = any chromosome that isn’t a sex chromosome  Sex Chromosome = genes that determine an individual’s gender (X and Y)  Sex chromosomes are the last pair on the karyotype

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21 Recessive Heredity  Caused by recessive alleles  Attached earlobes, Cystic fibrosis (defective protein leads to excessive mucus production in lungs), Albinism  Individual will only display the recessive phenotype if its genotype is homozygous recessive

22 Dominant Heredity  Caused by dominant allele  Freckles, Widow’s peak, Hitchhickers thumb, Huntington’s disease (brain degeneration, doesn’t appear until later in age), immunity to poison ivy  Individual will display the dominant phenotype if its genotype is heterozygous or homozygous dominant

23 When Heredity Follows Different Rules Chapter 12, Section 2

24 Incomplete Dominance  Complete Dominance = one allele completely dominates over another  Incomplete Dominance = phenotype of a heterozygote is in between the dominant & recessive phenotypes, appearance of a third phenotype

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26 Codominance  Both alleles for a gene are expressed in a heterozygous individual  Neither allele is dominant or recessive  Ex: Blood type  BLOOD TYPE.ppt BLOOD TYPE.ppt BLOOD TYPE.ppt

27 Sex Determination & Sex- linked Inheritance  Combination of sex chromosomes (X and Y) determine an individual’s gender  Males XY, X chromosome comes from mom & Y chromosome comes from dad  Females XX, both mom & dad give an X chromosome  Sex-linked Traits = traits controlled by genes on sex chromosomes

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29  Red-Green colorblindness  Hemophilia (blood doesn’t clot properly)  Male Pattern Baldness  Duchenne Muscular Distrophy (muscular degeneration leading to eventual paralysis)

30  Most of sex-linked traits are found on genes on the X chromosome (X-linked trait) because it is larger than the Y chromosome  X-linked traits display more in males because they only have 1 X chromosome, whereas females get 2 X chromosomes so they can be carriers of the trait but not display the phenotype

31 Polygenic Inheritance  Characteristics that are influenced by several genes


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