Transcript Gene Mutations

Gene Mutations
Mutations: a mistake made in
DNA
Gene Mutation
• Mutation that changes one gene
• The Rat Hid And The Cat Sat And Got Fat
• Substitute a letter in the sentence makes it
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•
•
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meaningless
The Pat Hid And The Cat Sat And Got Fat
Adding or deleting a letter is worse because ALL
words change
The Rat Hix Dan Dth Eca Tsa Tan Dgo Tfa T
The Rah Ida Ndt Hec Ats Atat Ndg Otf At
Consequences of mutations
• Amino acids make polypeptides which
makes proteins
• If one or more amino acids are wrong,
then the organism can’t build the correct
proteins
Gene Mutations: 2 types
• 1. Point mutations: mutation that occur at
one point in the sequence
• 2. Frameshift mutations: mutation that
shifts how all the codons are read
AGU CGG UGU AAG
•AGU CGG UUG UAA G
insertion
Frameshift Mutation
AGU CGG UGU AAG
•AGU CGG GUA AG
Deletion
Frameshift Mutation
AGU CGG UGU AAG
•AGU CGG UUU AAG
Substitution
Point Mutation
Chromosome Mutations
• Structure or number of chromosomes
change
Duplication
• Broken part can reattach to a sister
chromatid
• Normal chromosome
• ABCDE FGH
• Duplication of C and D
• ABCDCDE FGH
Deletion
• Normal chromosome
• ABCDE FGH
• Deletion of C and D
• ABE FGH
Inversion
• Broken part reattaches backwards
• Normal chromosome
• ABCDE FGH
• Inversion of B and C
• ACBDE FGH
Translocation
• Broken part attaches to ANOTHER
chromosome
• Normal chromosome
• ABCDE FGH
• CDM NOPQR
When do mutations occur?
• Mitosis
• Meiosis
Mitosis
• Occurs only in the individual and does
NOT get passed on to offspring
• Example: cancer
• Common reasons for mutations: UV
radiation from the sun, tanning booths, xrays, tobacco, asbestos, benzene,
chemical pesticides
Meiosis
• Mutations that are passed on to offspring
• Examples:
• Sickle cell disease: substitution
• Tay-Sachs: frameshift
• Down syndrome: chromosome mutation
on number 21