AP Biology Meiosis, Fertilization and Reproduction Lab Exercise

This exercise simulates the segregation of alleles and their homologous chromosomes in the meiotic production of monoploid gametes and the return to the diploid state when the homologous chromosomes from a male and a female are recombined in the process of fertilization.  Over the Winter Holidays the students interviewed their families in an attempt to determine their genotypes for a number of different human traits.

CHROMOSOME PAIR	CHARACTERISTIC
1	Tongue Rolling
1	Face Shape
1	Skin Pigmentation
2	Mid Digital Hair
2	Chin Type
2	Skin Pigmentation
3	Chin Shape
3	Hair Color
4	Skin Pigmentation
4	Red Hair Color
5	Hair Color
5	Cleft Chin
6	Bent Little Finger
7	Hair Texture
8	Hair Line
9	Eyebrow Thickness
9	Forehead Freckles
10	Hair Color
10	Eyebrow Placement
11	Eye Color
11	Eye Placement
12	Eye Color
12	Eye Size
13	Eye Shape
14	Nose Shape
15	Eye Lash Size
16	Dimples
17	Mouth Width
18	Hair Color
18	Lip Thickness
19	Nose Size
20	PTC Tasting
21	Cheek Freckles
22	Ear Lobe
Sex Pair (Y chromosome)	Hairy Pinna
Sex Pair (X chromosome)	Red Green Colorblindness

 

This exercise allows the student to examine the following genetic concepts:

dominant and recessive alleles;

sex linkage;

gene linkage;

independent assortment of alleles as it occurs during meiosis and gametogenesis;

polygenic inheritance;

how one gene can influence the affect of another gene (epistasis);

genotype and phenotype;

recognize that this variation of genes results in the production of offspring with unique phenotypes.

 
The students achieve this by putting their alleles on paper representations of their chromosomes. Each half of the chromosome representation is one member of a homologous pair. When the chromosome is folded and dropped only one allele found on one member the pair is passed to the child via the gamete.

By combining their chromosomes with the chromosomes of a classmate the new individual that would be formed receives the two alleles need to express a trait.   By completing this exercise twice the students see how their traits might combine in the production of an offspring. As the students complete this exercise they should come to appreciate the richness of variation that occurs as a result of the recombination of alleles during fertilization.

Student chromosomes

Samantha and Erica are preparing to rejoin their homologous chromosomes.

Each student in a pair drops their chromosomes to form a gamete and then the bring the chromosomes from each pile together matching homologous pairs as they would reform after fertilization of an egg by a sperm. They then tabulate the alleles to determine the traits of the new individual.

Cyrus and Malika are lining u heir homologous pairs.

Nastaran and Gina do the same. As the class does not have equal numbers of boys and girls some pairs had to be formed with two students of the same gender. In their to trials they alternate using male/female homologous pairs.

Andrew and Argentina are lining up their chromosomes.