Science 10 quarter 4

1. Mutations
PREPARED BY: TYPE YOUR NAME HERE

2. Explain how mutations may cause
changes in the structure and
function of a protein
S10LT - IIIe -38

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

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

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

6. Quick Review: What is a
chromosome?
 A chromosome is a DNA molecule
that is tightly coiled around proteins
called histones, which support its
structure, to form a thread-like
structures.

7. Types of Mutations

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

9. Chromosome Mutations
• Five types exist:
– Deletion
– Inversion
– Translocation
– Nondisjunction
– Duplication

10. Deletion
• Due to breakage
• A piece of a
chromosome is lost

11. Inversion
• Chromosome segment
breaks off
• Segment flips around
backwards
• Segment reattaches

12. Duplication
• Occurs when a
gene sequence is
repeated

13. Translocation
• Involves two
chromosomes that
are NOT homologous
• Part of one
chromosome is
transferred to
another chromosome

14. Translocation

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

16. Down Syndrome
 Down syndrome (DS or DNS), also
known as trisomy 21, is a genetic
disorder caused by the presence of all
or part of a third copy of chromosome
21. It is typically associated with
physical growth delays, characteristic
facial features and mild to moderate
intellectual disability.

17. Turner Syndrome
 A condition that affects only
females, results when one of the X
chromosomes (sex chromosomes)
is missing or partially missing.
Turner syndrome can cause a
variety of medical and
developmental problems, including
short height, failure of the ovaries to
develop and heart defects.

18. Klinefelter’s Syndrome
 A genetic disorder that affects males.
 Klinefelter’s syndrome occurs when a boy is born
with one or more extra X chromosomes. Most males
have one Y and one X chromosome. Having extra X
chromosomes can cause a male to have some
physical traits unusual for males such as weaker
muscles, greater height, poor coordination, less body
hair, and sterility

20. Chromosome Mutation
Animation

22. 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.

23. Types of Gene Mutations
• Include:
– Point Mutations
– Substitutions
– Insertions
– Deletions
– Frameshift

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

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

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

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

28. Amino Acid Sequence
Changed

29. Gene Mutation
Animation

30. Substitution Mutation
 A substitution is
a mutation that exchanges one
base for another (i.e., a change
in a single "chemical letter" such
as switching an A to a G)

31. Insertion Mutation
 The addition of one or more
nucleotide base pairs into a DNA
sequence

32. Deletion Mutation
 A part of a chromosome or a
sequence of DNA is lost during
DNA replication.
 Any number of nucleotides can
be deleted, from a single base to
an entire piece of chromosome

34. Normal Male
34
2n = 46

35. Normal Female
35
2n = 46

36. Male, Trisomy 21 (Down’s)
36
2n = 47

37. Female Down’s Syndrome
37
2n = 47

38. Klinefelter’s Syndrome
38
2n = 47

39. Turner’s Syndrome
39
2n = 45

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to the rightful owner. No copyright
infringement intended.