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Gene Mutations
D.S.Q
Tuesday Feb. 23
• 1. Why do children
resemble their parents?
• 2. Why don’t all people
look alike?
Look Alike Survey
What are genes?
• Genes are a section in the chromosome that
has genetic information
• Chromosomes are made of proteins and
DNA, which is an organism’s genetic
material
Genes
• Genes are located on all
chromosomes, autosomes, as well as
sex chromosomes.
• Each organism has a pair of each
autosome, one inherited from the
mother, the other inherited from the
father.
• Each organism also has a pair of sex
chromosomes, one inherited from
each parent.
How is DNA structured?
• DNA is like a twisted zipper, called a double helix.
• It get’s its shape from the nucleotides, which is a
molecule made of a nitrogen base, a sugar and a
phosphate group.
Mutations
• A mutation is a change in a nucleotide
sequence of a gene
• Humans have 23 paired chromosomes (so a total of
46) and we contain 20,000-25,000 genes that are
copied during DNA replication. Mistakes can
happen during this process.
• Mutations can be triggered by exposure to
X-rays, ultraviolet light, radioactive materials
and some kinds of chemicals.
Mutations
• If a mutation occurs in a body cell,
such as a skin cell, the mutation will not
be passed on to the organism’s
offspring.
• But if a mutation occurs in a sex cell
(egg or sperm), the mutation can be
passed on to an offspring and affect
the offspring’s traits.
Types of Mutations
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There are 3 types of mutations.
1. Deletion mutation
2. Insertion mutation
3. Substitution mutation
Deletion Mutation
• One or more nitrogen bases
are left out of the DNA
sequence
Insertion Mutation
• One or more nitrogen bases
are added to the DNA
Substitution Mutation
• One nitrogen base is
replaced by a different
nitrogen base
Effects of Mutations
• Mutations can be harmful, helpful or neither.
• A mutation is harmful if it reduces the organism’s
chances for survival and reproduction
• How would these two alligators affect their
environment they live in?
How cancer begins?
• Scientists think that cancer begins
when something damages a portion of
the DNA in a chromosome. The
damage causes a mutation and the
cells to function abnormally.
• Cancer begins when mutations disrupt
the normal cell cycle, causing cells to
divide in an uncontrolled way.
How is cancer related to
mutations?
• Cancer is a disease in which cells grow and
divide uncontrollably, damaging the parts of
the body around them.
• Cancer can be either inherited through your
parents or grandparents or causes by
substances in the environment, such as
cigarettes or ultraviolet lights from the sun or
tanning beds
DSQ
Thursday
• 1. Why do doctors ask if you have a family history of certain
diseases?
• 2. What is a mutation?
• 3. Are gene mutations always harmful to organism?
• 1. Many diseases are the result of inherited traits. A doctor can
predict your risk of having genetically inheritable diseases
based on your family’s medical history.
• 2. A mutation is a permanent change to an organisms genetic
code. Mutations can occur for a variety of reasons and may
result in new structural features or different functional
behaviors in the affected offspring.
• 3. No, not all mutations are harmful. Some mutations, such as
mutations that lead to cancer, are harmful. But there are
beneficial mutations such as the ability to digest lactose,
higher than normal bone density, and superior color vision.
Questions for
Rearranging Proteins
• 1. After placing the letter D in the sentence,
it did not make any sense. What kind of
mutation occurred?
• 2. After removing the letter H from the
sentence, it did not make any sense. What
kind of mutation occurred?
• 3. After inserting the letter D between the B
and the I and rearranging the letters, the
sentence did not make any sense anymore.
What kind of mutation occurred?