Mutations in organisms

1. Warm Up
1. Place DNA Extraction lab into the
basket located at the front
2. Pick up your plicker card from me
3. In your warm up notebook, write
down a few sentences answering
the following prompt:
If you could have the powers of
one animal, what would it be and
why?

2. https://www.youtube.com/watch?v=n4
2PunZ3Xno
https://www.youtube.com/watch?v=dg
83d4VziLk

3. Mutations

4. 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

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

6. 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)

7. 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.

8. Types of Mutations

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

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

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

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

13. Duplication
• Occurs when a
gene sequence is
repeated

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

15. Translocation

16. 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

17. 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.

18. 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.

19. 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

21. Chromosome Mutation
Animation

23. 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.

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

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

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

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

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

29. Amino Acid Sequence
Changed

30. Gene Mutation
Animation

31. 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)

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

33. 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

35. Normal Male
35
2n = 46

36. Normal Female
36
2n = 46

37. Male, Trisomy 21 (Down’s)
37
2n = 47

38. Female Down’s Syndrome
38
2n = 47

39. Klinefelter’s Syndrome
39
2n = 47

40. Turner’s Syndrome
40
2n = 45