1. CHANGES IN THE GENETIC CODE

6. Ectrodactyly

8. What do they all have in common?
They’re all mutations!

9. MUTATIONS a change in the DNA code
causes a different (sometimes wrong) type of protein to be made
may or may not be good for the organism

10. ALONG THE WAY good changes occur bad changes occur
changes that don’t matter either way

11. CHANGE IS NECESSARY without changes we would all look alike
without changes we would not evolve
without changes we would not develop immunities to disease
SO… Is change/variation a good thing???
YES!

12. Causes of Variation Crossing Over Mutations Some happen randomly
Some caused by Mutagens (agents that cause mutations)
Nuclear Radiation
Ultraviolet Light
X Rays

13. CROSSING OVER occurs when homologous chromosomes trade segments
occurs during Prophase I of Meiosis

14. entire gene is switched
involves the variation of a single trait
gene for big ears exchanges with gene for small ears

15. Advantages variation of offspring from parents
allows for “good” changes
Better chance of passing on genes for survival

16. 3 TYPES OF MUTATIONS Chromosomal mutations Gene mutations
Somatic mutations
these usually occur during mitosis and involve a chromosomal mutation
involved with body cells, not sex cells
tumors are the result

17. Research your mutation
1. Answer these questions
What does the name of the mutation mean?
What happens to the chromosome?
What is an example?

18. CHROMOSOMAL MUTATIONS
NONDISJUNCTION
DELETION
INVERSION
DUPLICATION
TRANSLOCATION
INSERTION

19. NONDISJUNCTION failure of homologous pairs to separate during meiosis
correct number of chromosomes are not present in the gamete
after fertilization, diploid number is not restored

20. Examples Trisomy 21(Down Syndrome)- 3 copies of chromosome 21
Klinefelters Syndrome- XXY
Turner Syndrome- X
“Supermales” - XYY

21. DELETION
A SEGMENT OF A CHROMOSOME IS DELETED

22. Examples
Cri-du-chat syndrome- “cry of the cat”- deletion of piece of chromosome #5
Angelman Syndrome- deletion of piece of chromosome #15
Prader-Willi Syndrome- deletion of piece of chromosome #15

23. INVERSION
A SEGMENT OF THE CHROMOSOME IS FLIPPED IN THE OPPOSITE DIRECTION

24. DUPLICATION
A SEGMENT OF THE CHROMOSOME IS COPIED TWICE

25. TRANSLOCATION
SEGMENTS FROM TWO DIFFERENT CHROMOSOMES ARE SWITCHED

26. Example Translocation Down Syndrome
Instead of being 3 separate copies of chromosome 21, the extra copy is actually attached to another chromosome

27. INSERTION
A SEGMENT OF ONE CHROMOSOME IS INSERTED INTO A DIFFERENT CHROMOSOME

28. GENE MUTATIONS POINT MUTATIONS FRAME SHIFT INVERSIONS insertions
deletions
INVERSIONS

29. LETS MUTATE! GCC TTA CGT TTA CGA CTG TAC GTA
Start with an original strand of DNA
GCC TTA CGT TTA CGA CTG TAC GTA
CGG AAT GCA AAT GCT GAC ATG CAT
A B C D
lets assume this strand codes for a protein
AMINO ACIDS

30. POINT MUTATIONS TTA CGT TTA CGA AAT GCA AAT GCT ORIGINAL
1 base is replaced with another base
TTA CTT TTA CGA
AAT GAA AAT GCT MUTATION B E

31. Example
Sickle Cell Anemia- changing 1 base causes mutation that codes for valine instead of glutamate in the protein hemoglobin
Individuals produce different type of hemoglobin
Red Blood Cells become sickle shaped and don’t pass thru blood vessels as easily
Cells die sooner than normal
Individuals don’t get as much oxygen

32. http://www. montgomerycollege

33. FRAME SHIFTS TTA CGT TTA CGA AAT GCA AAT GCT ORIGINAL A B C D
TTA CGT TTA ACG A
AAT GCA AAT TGC T INSERTION-base is inserted
A B C F
TTA CGT TAC GA
AAT GCA ATG CT DELETION- base is deleted
A B G

34. INVERSIONS TTA CGT TTA CGA AAT GCA AAT GCT ORIGINAL A B C D
Codon is found in reverse order
TTA TGC TTA CGA
AAT ACG AAT GCT INVERSION
A H C D

35. Consequences
Sometimes mutations are bad and cause for different proteins to be made
But- if you look at the amino acid chart- several different codons code for the same amino acids
Mutations can occur but wouldn’t be noticed
Some mutations are masked by other genes