Mutations
A mutation is a change of the DNA sequence within a
____________ of an organism resulting in the creation of a new
character or trait. In humans when parents pass their genes
down to their children, an average of 60 errors is introduced to
the genetic code. Out of the 6 billion letters of DNA (3 billion
base pairs) there are on average one new mutation in every 100
million letters of DNA.
A mutation can be harmful, helpful, or not be a factor to the
_____________________ of the organism.
Example: A mutation may cause an animal that usually has brown
fur to be born with white fur. It will be ________________ if the
white color makes it hard for the animal to hide from predators. An
example of a mutation that is helpful is when bright color patterns
appear on flower pedals. This makes the plant much more attract
for _____________________ insects.
Example of How a Mutation Occurs on the Gene
When a strand of DNA makes a _________________ of itself
during cell division, the Nucleotides or the base pairs can be
______________________ incorrectly, resulting in a mutated
gene. Nucleotides are the basic building block of nucleic acids,
such as DNA. For an example in a person with standard
pigmentation (skin color) the TYR gene appears as
ATCACTGTAG… In a person with albinism (__________ skin
pigmentation), it can be mistakenly copied as ACCATGTAG…
A
A
T
C
C
C
A
A
C
C
T
T
G
G
T
T
A
A
G
G
…
…
A second way a mutation can occur is when extra base pairs are
inserted into the ___________ sequence.
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A third way a mutation can occur is when ________ ________ are
removed from the original DNA sequence.
See examples on page 3(Human Genetic Disorders) and page 4
(Types of mutations that can occur).
Fortunately most mutations are _____________. Two common
methods of repair are when damaged base or bases are removed
and then replaced with the correct ones. An example is an incorrect
C is replaced by a T in the _________ pair. Another method is by
the use of special chemicals called enzymes. The purpose of an
enzyme in a cell is to allow the cell to carry out chemical reactions
very quickly. These reactions allow the cell to ________ things or
take things apart as needed.
Types of Mutations
Hereditary mutations are passed from parent to child. They are
present in the _____________ and ____________ cells of the
parent ( ______________ parents carry the gene for the mutation).
This type of mutation is present throughout a person’s life in
virtually every __________ in the body and is always passed on to
the next generation.
Mutations that occur only in an ________ or ____________ cell,
or those that occur just after fertilization, are called new (de novo)
mutations. These types of mutations ___________ be passed on to
the next generation.
Acquired (or somatic) mutations occur in the DNA of individual
cells at some time during a person’s ____________. These changes
can be caused by _________________________ factors such as
ultraviolet radiation from the sun, or can occur if a mistake is made
as DNA copies itself during cell __________________. These
types of acquired mutations _____________________ be passed
on to the next generation.
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