Do Now The function of the BRCA1 protein is to prevent our cells from becoming cancerous. If a cell...
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Do Now Do Now 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. TAC TGA GTT ACA CGA Write out the sequence of mRNA that would be produced during transcription of the BRCA1 gene.
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Transcript of Do Now The function of the BRCA1 protein is to prevent our cells from becoming cancerous. If a cell...
Do NowDo Now 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.
• TAC TGA GTT ACA CGA• Write out the sequence of mRNA that would be produced
during transcription of the BRCA1 gene.
Use the genetic code chart to determine the amino acids that make up this portion of the BRCA1 protein.
What would happen if a person’s BRCA1 protein was not functional?
What is this diagram saying?
Nucleotide Sequence
Amino Acid Sequence
Protein Shape
Protein Function
What is this diagram saying?
Nucleotide Sequence
Amino Acid Sequence
Protein Shape
Protein Function
HIS LEU VALGLY
Protein Protein SHAPESHAPE determines determines FUNCTIONFUNCTION..
FACT:FACT: Many people with breast cancer have BRCA1 proteins that are the wrong shape or missing amino acids.
How does this happen?How does this happen?
Mutations!Mutations!
Mutation Type
Description Example DNA Sequence
Substitution One base is switched with another
Original : ATCTGGMutated : TTCTGG
Insertion A base is added to a sequence
Original :ATCTGGMutated:ATCTGGG
Deletion A base is removed from a sequence.
Original : ATCTGGMutated : ATCTG
3 Types of Mutations
Identify the Mutation
Mutation A: ___________________________
Mutation B: ____________________________
Mutation C: ____________________________
GTTACGAA
GTTACTGAA
GTACGAA
GTTATGAA
Based on what you have learned thus far, create your own
definition of what a “mutationmutation” is
Stop and JotStop and Jot
MutationMutation- a random change in the sequence of bases.
Word of the DayWord of the Day
Discussion QuestionDiscussion Question
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?
Cancer ConnectionCancer ConnectionCompare the beginning sequence of Theresa’s BRCA1 gene to the normal sequence below.
Theresa’s BRCA1 gene: TACTGAGTTACTACGA
Normal BRCA1 gene: TACTGAGTTACACGA
Cancer ConnectionCancer Connection
How would her mRNA codonsmRNA codons be different than a normal person’s?
How would her amino acid sequenceamino acid sequence be different than a normal person’s?
Cancer ConnectionCancer Connection
State how the BRCA1 protein functionprotein function would be altered as a result of this mutation.
Cancer ConnectionCancer Connection
Synthesize all of the information that you learned today to describe why so many people in Theresa’s family have breast cancer.
Cancer ConnectionCancer ConnectionSample data from a patient is shown below. Fill in the patient’s missing codon.
DNA Sequence
mRNA Sequence
A. AcidSequence
Protein Shape
Normal TAC TGA GTT ACA CGA
AUG ACU CAA UGU GCU
Met Thr Gln Cys Ala
Normal BRCA1
Patient TAC TGT GTT ACA CGA
AUG ____CAA UGU GCU
Met Thr Gln Cys Ala
NormalBRCA1
Cancer ConnectionCancer ConnectionThe 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.
