Unit 5 Part 1: Is cancer in our genes?. Do Now.
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The function of the BRCA1 protein is to prevent our cells from becoming cancerous. If a cell is dividing too much, the BRCA1 protein can repair the cell so that it undergoes mitosis normally. A portion of the BRCA1 gene (the DNA with instructions on how to make the BRCA1 protein) is shown below.
What would happen if a person’s BRCA1 protein was not functional?
Amino Acid Sequence
Amino Acid Sequence
FACT:Many people with breast cancer have BRCA1 proteins that are the wrong shape or missing amino acids.
How does this happen?
Mutation A: ___________________________
Mutation B: ____________________________
Mutation C: ____________________________
Based on what you have learned thus far, create your own definition of what a “mutation” is
Mutation- a random change in the sequence of bases.
Insertions and deletions are often called “frameshift mutations” and are far more dangerous than substitution mutations. Why would an insertion or deletion be worse than a substitution?
Compare the beginning sequence of Theresa’s BRCA1 gene to the normal sequence below.
Theresa’s BRCA1 gene: TACTGAGTTACTACGA
Normal BRCA1 gene: TACTGAGTTACACGA
How would her mRNA codons be different than a normal person’s?
How would her amino acid sequence be different than a normal person’s?
State how the BRCA1 protein function would be altered as a result of this mutation.
Synthesize all of the information that you learned today to describe why so many people in Theresa’s family have breast cancer.
Sample data from a patient is shown below. Fill in the patient’s missing codon.
The patient’s BRCA1 protein is normal despite the fact that the BRCA1 gene has a mutation. Explain how this is possible in terms of the genetic code.