Genetics and Evolution

Report
Free Classroom Resources from
HHMI for Teaching Evolution,
Part 2
Megan Stine
stinem@hhmi.org
June 19, 2014
Evolution: Behind the Scenes
Evolving Switches, Evolving Bodies
• Film guides
• Virtual lab
• Classroom activities:
– Using Genetic Crosses to
Analyze a Stickleback
Trait
– Modeling the Regulatory
Switches of the Pitx1
Gene in Stickleback Fish
Evolving Switches, Evolving Bodies Film
• http://www.hhmi.org/biointeractive/makingfittest-evolving-switches-evolving-bodies
Which phenotype is dominant?
• Assumption: single-gene trait, 2 alleles, normal
dominance
• Cross between a marine stickleback and one from
Bear Paw Lake
• Parents are homozygous
• F is dominant, f is recessive
Predict the results of the crosses
1st generation
2nd generation
F
F
f
Ff
Ff
f
Ff
Ff
Pelvic spines present:absent =
1:0
0:1
F
f
F
FF
Ff
f
Ff
ff
Pelvic spines present:absent =
3:1
1:3
Sorting by Phenotype
With pelvic spines
Without pelvic spines
Do the data support your hypothesis?
• Sort the F1 cards:
– Fish with pelvic spines
– Fish without pelvic
spines
• Sort the F2 cards
• Ratio of fish with:without
pelvic spines in F1?
1:0
• Ratio of fish with:without
pelvic spines in F2?
3.4:1
Was our initial assumption correct? Is this a single-gene trait?
Was your hypothesis correct? Which phenotype is dominant?
Virtual Lab
Natural Selection in Humans
• Film guides
• Classroom resources:
– Nature of Science
– Mendelian Genetics,
Pedigrees, and Chisquare Analysis
– How Fibers Form
– Population Genetics
Natural Selection in Humans Film
• http://www.hhmi.org/biointeractive/makingfittest-natural-selection-humans
Mendelian Genetics Activity
•
•
•
•
•
Punnett squares
Pedigree analysis
Pedigree creation
Chi-square analysis
Data prediction
• Important notes:
– A is normal allele
– S is sickle cell allele
– AA has normal RBC
phenotype
– AS has sickle cell trait
– SS has sickle cell disease
Question #1: Intro Punnett
A
S
A
S
AA
AS
AS
SS
• Chance of normal RBC in
high and low oxygen?
• Chance of SCD?
• Chance of 3 children with
SCD?
• Chance of 2 children with
sickle cell trait and 1 with
SCD?
• Child without SCD, what
chance he/she has trait?
1/4
1/4
1/64
1/16
2/3
Question #6: Intro Pedigree
• Genotype of:
– 1st gen male?
– 2nd gen daughter?
– Individual #3?
AS
SS
AS
• If family moves to
lowlands of E. Africa, 4/5
males will have two
genetic advantages. What
are they?
Human Evolution Click & Learn
Teacher Guides
Holiday Lecture Series
BioInteractive.org
Coming in Fall 2014…
Thank you for your time and attention!
stinem@hhmi.org
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