Download Mutations

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Mutations
Chapter 12-4
+What are mutations?
Any
change to the genetic code
Causes:
Usually
error when DNA is being
replicated during mitosis
environmental factors: UV rays, X-rays,
drugs
Gene
A
mutations:
change in a single gene
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What are mutations?
point
mutation : Change of 1 or a few
nucleotide bases, possibly changing the
amino acid coded for
Example: Substitutions: one nitrogen
base substituted for another
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Effects of substitutions
Some
substitutions result in coding for
same amino acid
Some
change amino acid but doesn’t
affect overall protein
Some
change 1 amino acid and
changes structure of entire protein
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Sickle Cell Anemia
Normal
hemoglobin
Sickle Cell
Hemoglobin
sickle cell video
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Frameshift mutation: Shift in the
reading frame that causes every
amino acid after the mutation to be
different.
(Caused by Insertions or deletions)
Deletion

Insertion
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Effects of Frameshift mutations
Good:
 disables
CCR5 HIV receptor which allows HIV
virus to attack Immune cells
 Mutations that allow evolution of species
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Negative Examples:
Causes
disorders:
Tay Sachs
Chron’s disease
Cystic Fibrosis
Cancer
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Cystic Fibrosis
A
mutation in the CFTR gene
 The
CFTR gene makes a protein that controls the
movement of salt and water in and out of your
body's cells.
 In people who have CF, the gene makes a
protein that doesn't work well.
70%
of cases caused by this mutation
ATCATCTTTGGTGTTTCC
lle lle Phe Gly Val Ser
ATCAT TGGTGTTTCC
lle lle
Gly Val Ser
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Results of Cystic Fibrosis
Thick
mucus is produced by the body
Mucus fills lungs causing lung
infections
Mucus
blocks pancreas which causes
digestive problems
Mucus
can block bile ducts in liver
causing liver failure.
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Cancer

results from a series of mutations
within a single cell

Often, a faulty, damaged, or missing
p53 gene is to blame

The p53 gene makes a protein that
stops cells from dividing

Without this protein, cells divide
unchecked and become tumors.
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Tay Sachs
 The
HEXA gene makes part of an enzyme called
beta-hexosaminidase A
 enzyme
helps break down a fatty substance called
GM2 ganglioside in nerve cells of brain
 Mutations
in the HEXA gene disrupt the activity of
beta-hexosaminidase A, preventing the breakdown of
the fatty substances.
 As
a result, the fatty substances accumulate to deadly
levels in the brain and spinal cord.
 The
buildup of GM2 ganglioside causes progressive
damage to the nerve cells
+What are mutations?
Chromosomal
mutations: may change
the location of genes and number of genes
4 Types:
1)
Deletion: Loss of part/all of chromosome
2)
Duplication: Segment is repeated
+ 3. Inversion- part of chromosome
becomes orientated in opposite direction
 4. Translocation-
part of one
chromosome breaks off and attaches to
another
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Intro to Cancer Biology video