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Mutations. What Are Mutations? Changes in the nucleotide sequence of DNA Changes in the nucleotide sequence of DNA May occur in somatic cells (aren’t.

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Presentation on theme: "Mutations. What Are Mutations? Changes in the nucleotide sequence of DNA Changes in the nucleotide sequence of DNA May occur in somatic cells (aren’t."— Presentation transcript:

1 Mutations

2 What Are Mutations? Changes in the nucleotide sequence of DNA Changes in the nucleotide sequence of DNA May occur in somatic cells (aren’t passed to offspring) May occur in somatic cells (aren’t passed to offspring) May occur in gametes (eggs & sperm) and be passed to offspring May occur in gametes (eggs & sperm) and be passed to offspring

3 Are Mutations Helpful or Harmful? Mutations happen regularly Mutations happen regularly Almost all mutations are neutral Almost all mutations are neutral Chemicals & UV radiation cause mutations Chemicals & UV radiation cause mutations Many mutations are repaired by enzymes Many mutations are repaired by enzymes

4 Are Mutations Helpful or Harmful? Some type of skin cancers and leukemia result from somatic mutations Some type of skin cancers and leukemia result from somatic mutations Some mutations may improve an organism’s survival (beneficial) Some mutations may improve an organism’s survival (beneficial)

5 Types of Mutations

6 Chromosome Mutations May Involve: May Involve: –Changing the structure of a chromosome –The loss or gain of part of a chromosome

7 Chromosome Mutations Five types exist: Five types exist: –Deletion –Inversion –Translocation –Nondisjunction –Duplication

8 Deletion Due to breakage Due to breakage A piece of a chromosome is lost A piece of a chromosome is lost

9 Chromosome Mutations Cri-du-chat Cri-du-chat –Deletion of material on 5 th chromosome –Characterized by the cat-like cry made by cri-du-chat babies –Varied levels of metal handicaps

10 Inversion Chromosome segment breaks off Chromosome segment breaks off Segment flips around backwards Segment flips around backwards Segment reattaches Segment reattaches

11 Duplication Occurs when a gene sequence is repeated Occurs when a gene sequence is repeated

12 Translocation Involves two chromosomes that aren’t homologous Involves two chromosomes that aren’t homologous Part of one chromosome is transferred to another chromosomes Part of one chromosome is transferred to another chromosomes

13 Translocation

14 Nondisjunction Failure of chromosomes to separate during meiosis Failure of chromosomes to separate during meiosis Causes gamete to have too many or too few chromosomes Causes gamete to have too many or too few chromosomes Disorders: Disorders: –Down Syndrome – three 21 st chromosomes –Turner Syndrome – single X chromosome –Klinefelter’s Syndrome – XXY chromosomes

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17 Chromosome Mutation Animation

18 Gene Mutations Change in the nucleotide sequence of a gene Change in the nucleotide sequence of a gene May only involve a single nucleotide May only involve a single nucleotide May be due to copying errors, chemicals, viruses, etc. May be due to copying errors, chemicals, viruses, etc.

19 Types of Gene Mutations Include: Include: –Point Mutations –Substitutions –Insertions –Deletions –Frameshift

20 Point Mutation Change of a single nucleotide Change of a single nucleotide Includes the deletion, insertion, or substitution of ONE nucleotide in a gene Includes the deletion, insertion, or substitution of ONE nucleotide in a gene

21 Point Mutation Sickle Cell disease is the result of one nucleotide substitution Sickle Cell disease is the result of one nucleotide substitution Occurs in the hemoglobin gene Occurs in the hemoglobin gene

22 Frameshift Mutation Inserting or deleting one or more nucleotides Inserting or deleting one or more nucleotides Changes the “reading frame” like changing a sentence Changes the “reading frame” like changing a sentence Proteins built incorrectly Proteins built incorrectly

23 Frameshift Mutation Original: Original: –The fat cat ate the wee rat. Frame Shift (“a” added): Frame Shift (“a” added): – The fat caa tet hew eer at.

24 Amino Acid Sequence Changed

25 Gene Mutation Animation

26 HOX GENES A series of genes that control the differentiation of cells and tissues in the embryo. A series of genes that control the differentiation of cells and tissues in the embryo. Hox genes determine an animal’s basic body plan Hox genes determine an animal’s basic body plan

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28 POLYDACTYLE

29 FYI

30 Normal Male 30 2n = 46

31 Normal Female 31 2n = 46

32 Male, Trisomy 21 (Down’s) 32 2n = 47

33 Female Down’s Syndrome 33 2n = 47

34 Female with Down’s Syndrome

35 Klinefelter’s Syndrome 35 2n = 47

36 Sex Chromosome Abnormalities Klinefelter’s Syndrome Klinefelter’s Syndrome –XXY, XXYY, XXXY –Male –Sterility –Small testicles –Breast enlargement

37 XYY SYNDROME

38 Sex Chromosome Abnormalities XYY Syndrome XYY Syndrome –Normal male traits –Often tall and thin –Associated with antisocial and behavioral problems

39 Turner’s Syndrome 39 2n = 45

40 Sex Chromosome Mutations Turner’s Syndrome Turner’s Syndrome –X0 –Female –sex organs don't mature at adolescence – sterility –short stature – sterility –short stature

41 Sex Chromosome Mutations XXX XXX –Trisomy X –Female –Little or no visible differences –tall stature –learning disabilities –limited fertility


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