Participants Facilitator Virginia Carson Chris Tubbs Charlie Janson Devon Quick John Reiss Melissa RowlandGoldsmith Mark Wilson Learning goals Students will understand characteristics of evidence in science ID: 599059
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Slide1
Heredity Tidbit
Participants: Facilitator:
Virginia
Carson Chris
Tubbs
Charlie Janson
Devon Quick
John Reiss
Melissa Rowland-Goldsmith
Mark Wilson Slide2
Learning goals
Students will understand characteristics of evidence in science
Students will confidently choose and defend evidence-based positions
Students will understand the relationship between genotype and phenotypeSlide3
Context
Students have covered concepts of
Probability vs. frequency
Mutations
Genotype
PhenotypeSlide4
Learning outcomes
Students
will be able to interpret a graph relating
genotype to phenotype
Students
will be able to recognize and
interpret environmental
effects on phenotype/genotype relationships
Students will be able to apply the concepts of expressivity and penetrance to an example of population variation
Slide5
The phenotype of breast cancer
Background:
Normal BRCA is protective gene against breast cancer (codes for a tumor suppressing protein)
Some people have BRCA gene mutation that makes the protective protein non-functional (tumors not suppressed)
Several mutations of this gene identifiedSlide6
Clicker Question:
Do genes cause breast cancer?
Yes
NoSlide7
Look at my Frogs
The frogs in population A are genetically identical and look the same.
GROUP A
genotype A1/A1:Slide8
Look, more Frogs
The frogs in B are also genetically identical (to each other)
What might explain why some B frogs have spots and other do not? (shout out)
GROUP A
genotype A1/A1:
GROUP B
genotype A2/A2:Slide9
Oh wait, I have more Frogs
The frogs in C are genetically identical (to each other), but have variable numbers of spots
What is different about the pattern of variation in C compared to B? (talk with your neighbor)
GROUP A
genotype A1/A1:
GROUP B
genotype A2/A2:
GROUP C
Genotype A3/A3:Slide10
What caused all the variations?
http://www.herpnet.net/Iowa-Herpetology/index.php?option=com_content&task=view&id=29&Itemid=26Slide11
Scientific jargon
Complete
penetrance
Incomplete
penetrance
Complete
penetrance
, variable
expressivity
GROUP A
genotype A1/A1:
GROUP B
genotype A2/A2:
GROUP C
Genotype A3/A3:
1 – minute paper, then swapSlide12
Summary
Genotype is NOT always = Phenotype!
Environmental factors and chance events affect both
penetrance
and
expressivitySlide13
Clicker Question:
So, now what do you think, does a gene cause breast cancer?
Yes
NoSlide14
Incidence of breast cancer vs. age of women in USSlide15
Incidence of breast cancer vs. age of women in USSlide16
Incidence of breast cancer vs. age of women in US
What does this red line tell you? (shout out)Slide17
Clicker Question:
Using the graph, will everyone with the BRCA mutation develop breast cancer?
Yes
NoSlide18
Factors associated with Breast Cancer
You could do some research on this and list specific environmental effects, chance and genetics as making someone more susceptible to developing breast cancer, but simply having the gene mutation on BRCA does not mean one will always develop breast cancer.
The severity of breast cancer relates to expressivity. If one breast is affected or two or the ovaries as well – the more cancer, the more expressivity.Slide19
Clicker Question:
What do you think now?
Does a gene cause breast cancer?
Yes
No
Sometimes?Slide20
Breast Cancer Incidence
Q: which of these is true?
Most people with breast cancer have the BRCA1 mutation
B. BRCA1 mutation is 100%
penetrant
C. More than 50% of people with BRCA1 mutation will develop breast cancerSlide21
Putting it in a Bigger Context:
Breast cancer and BRCA1 incidence in US womenSlide22
After today
You should be more familiar with graphical representation of data
You should recognize that environment and genotype influence phenotype
You should be able to define and apply
the concepts of expressivity and penetrance to an example of population variation
Slide23
Summative assessment: Essay Question
Your sister has just met with a genetic counselor. The genetic counselor told her that she had the mutated form of the BRCA1 gene and provided her the accompanying graph.
Explain to your sister why this is not a death sentence.
How is this example relevant to the idea that genotype does not equal phenotype? Hint: use the words penetrance and expressivity. Slide24
Alternative graph that could be used, includes family history