Download Genetic Mutations

Human Inheritance
& Genetic Mutations
At the End of Today,
You Should Know:
1. Connect the terms gene, chromosome &
DNA.
2. Explain how humans get their traits.
Include two main sources.
3. Classify human traits into three groups.
4. Define mutation.
5. Describe harmful mutations.
6. Identify what makes a mutation neutral.
7. Provide examples of beneficial
mutations.
1. Living things are made of
cells, which are the smallest
structural and functional unit
of the organism. Here are
some examples…
Onion Cells
Cork Cells
Frog Blood Cells
Human Cheek Cell
• Inside the nucleus of most
cells are the chromosomes,
which are composed of DNA.
• Small sections of DNA are
called genes.
• These are the instructions for
absolutely everything that goes
on within the organism.
How is a chromosome like
a roll of toilet paper?
Random Fact…
If you took all the DNA from
each of the cells in your body
and stretched it out end to
end, it would be long enough
to reach from the earth to the
sun and back – about 60 times!
• The approximately
25,000 genes in each
of our cells is
responsible for
determining all of the
initial traits about a
human. Remember…
these genes came
from our parents.
• Once born, the
environment plays
just as a significant
role in shaping who
you are.
There are three kinds of traits:
1. Physical
2. Behavioral
3. Predisposition to Disease
We all inherit an initial set of
each, but the environment and
the choices we make can
change how these traits are
displayed.
What is a Mutation?
Definition:
A change in a gene or a
chromosome
The term mutation comes from the Latin
word for “change”
What is a Mutation?
• Abrupt changes in a single gene or a
region of a chromosome that may be
passed genetically.
• Mutations are the fuel for evolution and
are the basis for the variation in
population… we will be talking more
about this!
• Whether a mutation is harmful, helpful, or
neutral depends on the organism’s
environment.
Harmful Mutations
A mutation is considered harmful to the
organism if it impedes the organism’s ability
to…
Some
Mutations
Cause
Disorders…
One Wrong Letter
As you watch this video clip, please
think about…
• Taye-Sachs Disease is caused by a
mutation. One letter is incorrect in
the affected child’s DNA. It is a
recessive mutation. What does that
mean?
• What does it mean to be a carrier of a
disease?
8:57
Should We Screen for Cancer?
As you watch this video clip, please
think about…
• It is becoming more common (and
cheaper) to map your genome. Is
this something you’d be interested in
doing? Why or why not?
3:55
Not all
Mutations
Are Bad…
Mutations Can Be Neutral
• They may have little or no effect on the
survival of an organism or on its ability to
reproduce.
• Most mutations within the DNA are “covered”
or compensated for by other, normal genes.
• 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 50100 mutations within their DNA - most (if not
all) are neutral or beneficial.
Mutations Can Be Neutral
• Scientists can trace blue eyes to one person
who originally had the mutation.
• The same is true for people with red hair. That
trait is caused by a genetic mutation.
• Are these beneficial or harmful? Chances are
one would say… Not really either. They
would be considered neutral.
• Most neutral mutations aren’t even known to
the organism… Think of it as an email or a
text message with a typo. The meaning is still
understood, unless it is a MAJOR typo.
Neutral Mutations
A mutation is considered neutral to the
organism if it neither impedes nor benefits
the organism’s ability to…
Yes, There Are
Beneficial
Mutations
Mutations Can Be Beneficial
• Bacterial resistance to antibiotics (beneficial to
the bacteria, not to humans)
• Insecticide resistance in bugs (beneficial to
bugs, not to humans)
• Seedless watermelon (beneficial to humans,
difficult for the watermelon to reproduce)
• Ability to digest lactose… Did you know it is a
mutation that give humans the ability to digest
cow’s milk? Scientists think that this
originated from farmers who needed to drink
animal milk to survive (and reproduce)
Beneficial Mutations
A mutation is considered beneficial to the
organism if it benefits the organism’s ability
to…
Double Immunity
• Why is this segment titled,
“Double Immunity?”
• For which organism is this
mutation considered harmful?
• What might be done with the
knowledge of this mutation?
2:22
Sometimes There’s a
Trade-Off
• Sometimes you can get a beneficial
mutation that has a drawback.
• 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.
A Mutation Story
• Would this mutation be considered
harmful, neutral, or beneficial
• Defend your answer…
4:50
Check Yourself:
Can you answer…
1. Connect the terms gene, chromosome &
DNA.
2. Explain how humans get their traits.
Include two main sources.
3. Classify human traits into three groups.
4. Define mutation.
5. Describe harmful mutations.
6. Identify what makes a mutation neutral.
7. Provide examples of beneficial