Mutations
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Transcript of Mutations
![Page 1: Mutations](https://reader036.fdocuments.net/reader036/viewer/2022081900/58f041771a28ab25608b4585/html5/thumbnails/1.jpg)
Mutations
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Why are proteins so important?
• Proteins determine what a person’s traits (physical features) will be.
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Why do people have different traits?• People have different traits (like different eye color
and hair color) because they have different nucleotide sequences.
• Different nucleotide sequences result in different types of proteins, which results in different physical traits.
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What is a mutation?• When the DNA changes.• Changes in the nucleotide sequence can
change the amino acids, which changes the protein that is made, which changes a person’s physical traits.
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Processing Piece:
• These are examples of insertions:AAT ACATTAC TACA
• Try to come up with your own definition for an insertion.
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Processing Piece:
• These are examples of deletions:AAT ATTAC TC
• Try to come up with your own definition for an deletion.
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Processing Piece:
• These are examples of substitutions:AAT ACATTAC TACA
• Try to come up with your own definition for an substitution.
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What are insertions, deletions, and substitutions?
• Insertion: Extra bases (“letters”) are added to the nucleotide sequence.
Example: AAT AATC• Deletion: Bases are removed from the nucleotide
sequence.Example: AAT AT• Substitution: A base is replaced with another.Example: AAT ACT
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Processing Piece:
• These are examples of point mutations:AAT ACATTAC TACA
• These are NOT examples of point mutations:AAT AATAAT
AAT TTry to come up with a definition.
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Processing Piece:
• These are examples of missense mutations:Ser – leu –leu Ser – tyr – leuMet – ala - ser Ala – ala - ser
• These are NOT examples of missense mutations:Ser – leu –leu Ala – tyr – leu
Met – ala - ser Cyt – ana - serTry to come up with a definition.
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Processing Piece:
• These are examples of nonsense mutations:Ser – leu –leu Ser – stopMet – ala - ser Ala – stop
Try to come up with a definition.
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Processing Piece:
• These are examples of silent mutations:Ser Ser Ala Ala
Try to come up with a definition.
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What are point, missense, nonsense, and silent mutations?
• Point mutation: when a single base (“letter”) is inserted, deleted, or substituted.
• Missense mutation: When there is a substitution, and 1 amino acid changes.
• Nonsense mutation: When a mutation creates a stop codon in the gene, and the polypeptide chain is cut short.
• Silent mutation: When there is a substitution, but none of the amino acids change.
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Processing Piece:
• This is an example of frameshift mutations:AAT CAT TAT GAT ATC ATT ATG AT
Try to come up with a definition.
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What is a frameshift mutation?
• When 1 or 2 bases are inserted or deleted, and every codon after the mutation changes.
(Example: TAG TAG TAG becomes AGT AGT AG after the first A is deleted.)
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4) Original DNA: ATA AGG GAA CGA. • mRNA:
______________________________________• Amino acids:
______________________________________
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Original DNA: ATA AGG GAA CGA. 5) Now remove the T from the orginal DNA (from #4), and write the new DNA sequence below: • Mutated DNA:
_________________________________________________• Mutated mRNA:
_________________________________________________• Mutated amino acids:
_________________________________________________ • Was the mutation an insertion, deletion, or substitution?
_______________________________________________• Did the mutation cause a frameshift? _________ How do you
know?
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6) Now remove the C from the original DNA. Is this an insertion, deletion, or substitution? __________• Mutated DNA:
________________________________________• Mutated mRNA:
_________________________________________• Mutated amino acids:
________________________________________• Did this mutation cause a frameshift? _________
How do you know?
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Exit Ticket1) Are different physical traits caused by different
amounts of DNA, or by different nucleotide sequences?
2) Which will cause more changes to the amino acid sequence: Inserting one base in the middle of a gene, or inserting 3 bases at the beginning of a gene?
3) Why?