With special thanks to Kathrin StangerHall and Jess Blum University of North Carolina Chapel Hill Jean DeSaix Kelly Hogan University of California Santa Barbra Rolf Christoffersen Stu Feinstein ID: 576858
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Mendel’s Mighty Missing Meiotic Mechanism
With special thanks toKathrin Stanger-HallandJess Blum
University of North Carolina, Chapel HillJean DeSaixKelly HoganUniversity of California, Santa BarbraRolf ChristoffersenStu FeinsteinKansas State UniversityEva HorneRobbie BearSlide2
Teachable Unit: Heredity
Topic: Connecting Meiosis with Mendelian InheritanceContext: Large Introductory Biology Course.
Assumed Basic Knowledge: Chromosome segregation into gametes during meiosis Mendelian inheritanceSlide3
Learning Goal
: How meiosis relates to the inheritance of alleles of two traits.Learning Outcome for Teachable Tidbit: Predict how the arrangement of chromosomes in meiosis I will determine the allele combinations in a
Punnett Square.Slide4Slide5
Tidbits
AaBb
aabb
A = active
a = passiveB = bigb = little
Active & Big
passive & littleSlide6
a
b
A
B
Gonad
Single cell
Tidbit Slide7
Each person = chromosome
Color indicates parental origin - pink = maternal origin - blue = paternal originLetter = allele
a
b
A
BSlide8
What is the relationship between the chromosome
carrying the “A” allele and the chromosome
carrying the “a”allele?Check your vocabulary…Homologs
Is a Tidbit gonad cell a diploid or a haploid cell and how do you know?
Diploid
vs.
Haploid
- same genes, can be different alleles
Two sets of all
chromsomes
. Example: AABB
One set of all chromosomes. Example: ABSlide9
You are all the directors of this show!
What needs to happen before we start our production of meiosis?Slide10
Check your vocabulary…
What is the relationship between the chromatid carrying the “a” allele and the other chromatid attached to it carrying the “a”allele
?Sister chromatidsHomologs - same genes, can be different alleles
- same genes, identical allelesSlide11
At metaphase I, how should the alleles be arranged on the metaphase plate?
A)
D)
B)
C)
A
A
a
a
B
B
b
b
B
B
b
b
A
A
a
a
A
A
a
a
B
B
b
b
b
b
B
B
A
A
a
aSlide12
At metaphase II, how should the alleles be arranged on the metaphase plate?
A)
D)
B)
C)
b
b
B
B
A
A
a
a
A
A
B
B
a
a
b
b
A
A
B
B
a
a
b
b
b
b
A
A
B
B
a
aSlide13
When the actors did this, why did we only get half of the expected types of gametes?Slide14
Gonad
A
A
a
a
B
B
b
b
b
b
B
B
A
A
a
a
b
b
B
B
A
A
a
a
A
A
a
a
B
B
b
bSlide15
How can we get all of the possible gamete types?
D)
B)
A
A
a
a
B
B
b
b
b
b
B
B
A
A
a
a
Homework:
Draw the two cells that would result from meiosis I for options B and D.
Then draw the outcome of meiosis II for both options