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Mutations. What Are Mutations? Changes in the nucleotide sequence of DNA May occur in somatic cells (arent passed to offspring) May occur in gametes (eggs.

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Presentation on theme: "Mutations. What Are Mutations? Changes in the nucleotide sequence of DNA May occur in somatic cells (arent passed to offspring) May occur in gametes (eggs."— Presentation transcript:

1 Mutations

2 What Are Mutations? Changes in the nucleotide sequence of DNA May occur in somatic cells (arent passed to offspring) May occur in gametes (eggs & sperm) and be passed to offspring

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

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

5 Types of Mutations

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

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

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

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

10 Duplication Occurs when a gene sequence is repeated

11 Translocation Involves two chromosomes that arent homologous Part of one chromosome is transferred to another chromosomes

12 Translocation

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

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15 Chromosome Mutation Animation

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

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

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

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

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

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

23 Amino Acid Sequence Changed

24 Gene Mutation Animation

25 FYI

26 Normal Male 26 2n = 46

27 Normal Female 27 2n = 46

28 Male, Trisomy 21 (Downs) 28 2n = 47

29 Female Downs Syndrome 29 2n = 47

30 Klinefelters Syndrome 30 2n = 47

31 Turners Syndrome 31 2n = 45


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