Genetic Mutations

What are some genetic mutations and what is their affect?

1. Genetic Mutations

2. •What is a mutation?
•What are some examples of harmful
mutations?
•Neutral Mutations are…
•What are some examples of beneficial
mutations?
At the End of Today, You
Should Know:

3. What is a Mutation?
•Abrupt, heritable changes in a single
gene or a region of a chromosome, can
also include alterations in chromosome
number
•Mutations are the fuel for evolution and
are the basis for the variation in
population.

4. What is a Mutation?
•Can be when one letter is switched -
accidentally copied incorrectly within the DNA.
•When one section of the DNA, sometimes an
entire gene, is not properly connected to the
rest of the DNA; sometimes it even reconnects
to another chromosome
•One section of DNA, sometimes an entire gene,
appears more than once

5. What is a Mutation?
•More or less chromosomes than 46
•Will only get passed on to offspring when
the sex cells contain the mutation
•Can be caused after birth by
environmental factors like radiation and
chemicals, which can alter a person’s
DNA, even in their sex cells, causing their
offspring to have disorders

6. Some Mutations Cause
Disorders…

7. Down’s Syndrome
• Offspring receives 3 copies of 21
st

chromosome
•90% of the time the extra chromosome
comes from the mother
•Affects 1 in 800 live births

8. Effects of Down’s Syndrome
•Different in each person
•Does not usually pass this onto children
•Common effects include
–Learning Disabilities
–Heart defects (can usually be corrected
with modern technology)

11. Turner’s Syndrome
•45 (instead of 46) chromosomes
•offspring are born with one X
chromosome (no Y; only one X)
•only affects women
•In about 80% of cases the X comes
from the mother and the father’s sperm
has no Y
•Affects 1 in 2500 live births

12. Effects of Turner’s Syndrome
• Sometimes a lack of ovarian
development
• Can have more masculine qualities
(stronger), although are female
•In some cases:
–Webbed neck
–Arms that turn in at the elbow
–Low hairline on the back of the head

15. Klinefelter’s Syndrome
• Offspring inherit a Y chromosome and two
X chromosomes
•Because there is a Y all offspring are male
•Sometimes the extra X comes from the egg
and sometimes it comes from the sperm
•Occurs in 1 out of every 500 – 1000 live
births

16. Effects of Klinefelter
Syndrome
•Sparse facial and body hair
•Underdeveloped muscles
•Wide hips
•Tall height
•Long legs & arms
•Higher-pitched voice

18. Albinism
•Caused by a recessive gene
•Causes genes to release unusual
amounts of melanin (chemical that
provides color)
•Affects 1 in 17,000 people
•People of all races are susceptible
•All animals are susceptible

19. Effects of Albinism
•Light skin
•Light hair
•Reddish or violet eyes (in some albinos)
•Lack of eye pigment leads to vision
problems
•Skin cancer – especially in third world
countries

28. There are MANY other
mutations…

29. Not all
Mutations
Are
Bad…

30. Mutations Can Be Neutral
•They may have little or no effect on the
survival of an organism or on its ability to
reproduce.
•They may result in the same kind of organism
- meaning that the change still tells the cell to
do what it should, so there is no difference.
•It is estimated that the average human has
50-100 mutations within their DNA - most (if
not all) are neutral or beneficial

31. Mutations Can Be Beneficial
•Bacterial resistance to antibiotics
•Insecticide resistance in bugs
•Rapid mutation rates in virus’s proteins
allowing them to adapt to new “hosts”

32. Mutations Can Be Beneficial
•In humans, it can be a different set of
circumstances… Here’s an example:
•Sickle-Cell Anemia is a genetic disorder in
which there is a defect in the structure of red
blood cells. This leads to fatigue and anemia
when not treated.
•However, it has been found that people who
are carriers for Sickle-Cell Anemia also has
some genetic protection against another
disease, malaria.

33. Mutations Can Be Beneficial
• In evolutionary studies, scientists have
connected the presence of a brain chemical
microcephalin (a proposed mutation) with the
human’s development of art, music, and
complex tool-making practices
•This same research indicates that the human
brain is still evolving and becoming more and
more capable of more complex tasks
•Some humans have been found to have
mutations that protect them from other
diseases, such as AIDS