244
CL N AS OT SR F OO OR M US E
4. Randomly align the homologous chromosome pairs to simulate alignment on the metaphase plate (as occurs in metaphase I). Simulate anaphase I by separating chromosome pairs. For each group of four sticks, two are pulled to each pole.
T
t
T
t
t
T
t
T
LB LB
LB LB
LB LB
10 10
10 10
10 10
10 10
PR E O V N IE LY W
LB LB
r
r
r
LB LB 2
r
r
LB LB
LB LB
2
2
r
r
2
2
r
LB LB
2
2
2
5. Telophase I: Two intermediate cells are formed. If you have been random in the previous step, each intermediate cell will contain a mixture of maternal and paternal chromosomes. This is the end of meiosis 1.
Now that meiosis 1 is completed, your cells need to undergo meiosis 2. Carry out prophase II, metaphase II, anaphase II, and telophase II. Remember, there is no crossing over in meiosis II. At the end of the process each intermediate cell will have produced two haploid gametes (below). Intermediate cell 2
t
Intermediate cell 1
t
T
T
r
r
r
Paternal chromosome
LB
r
LB 2
Haploid (N) gamete
10
Maternal chromosome
10
LB
Maternal chromosome
LB 2
LB 2
t
t
r
r
r
T
10
LB 2
LB 2
LB 10
LB 10
LB 2
N AS OT SR F OO OR M US E
LB 2
10
LB
LB
T
r
LB 2
LB LB 10 10
6. Pair up with the partner you chose at the beginning of the exercise to carry out fertilisation. Randomly select one sperm and one egg cell. The unsuccessful gametes can be removed from the table. Combine the chromosomes of the successful gametes. You have created a child! Fill in the following chart to describe your child's genotype and phenotype for tongue rolling and handedness.
Handedness Tongue rolling
Phenotype
Genotype
CL
Trait
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