mutations gene mutations change in the nucleotide sequence of a gene may only involve a single...
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MutatioMutationsns
Gene Mutations
• Change in the nucleotide sequence of a gene
• May only involve a single nucleotide
• May be due to copying errors, chemicals, viruses, etc.
Types of Gene Mutations
• Include:–Point Mutations–Substitutions– Insertions–Deletions–Frameshift
Point Mutation
• Change of a single nucleotide
• Includes the deletion, insertion, or substitution of ONE nucleotide in a gene
AP Biology
When do mutationsaffect the nextgeneration?
Mutations Point mutations
single base change base-pair
substitution silent mutation
no amino acid change redundancy in code
Missense mutation change amino acid
Nonsense mutation change to stop codon
AP Biology
Point mutation leads to Sickle cell anemiaWhat kind of mutation?
Missense!
Point Mutation
•Sickle Cell disease is the result of one nucleotide substitution
• Occurs in the hemoglobin gene
AP Biology
Sickle cell anemia Primarily Africans
recessive inheritance pattern strikes 1 out of 400 African Americans
hydrophilicamino acid
hydrophobic amino acid
Frameshift Mutation
• Inserting or deleting one or more nucleotides
• Changes the “reading frame” like changing a sentence
•Proteins built incorrectly
AP Biology
Mutations Frameshift
shift in the reading frame
changes everything “downstream”
insertions adding base(s)
deletions losing base(s)
Where would this mutation cause the most change:
beginning or end of gene?
Frameshift Mutation
• Original:–The fat cat ate the wee rat.
• Frame Shift (“a” added):– The fat caa tet hew eer at.
Amino Acid Sequence Changed
Gene Mutation Animation
AP Biology
Deletion leads to Cystic fibrosis
loss of oneamino acid
delta F508
Cystic fibrosis is a disease passed down through families that causes thick, sticky mucus to build up in the lungs, digestive tract, and other areas of the body.
AP Biology
Hemophilia Individuals blood does not clot
normally.
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