Download Meiosis and Fertilization

Genetics
State Standard:
H.1L.3 -- Explain and apply laws of heredity and their relationship
to the structure and function of DNA.
Score
5
Response
Excellent
4
Proficient
3
Adequate
2
Incorrect
1
Fails to complete
Reader / Writer Name
Timer /Materials Person
Group Scoring Rubric 1-4
Responses are clear, complete and demonstrate a thorough
understanding of the subject matter
Completes the assignment or experiment satisfactorily, but
the explanations have minor flaws
Begins the assignment and explanation satisfactorily; but
omits significant parts or fails to complete.
Assignment and its explanations are not accurate. Group
did not demonstrate understanding or authentic knowledge
Did not participate
Meiosis and Fertilization
Meiosis is the form of cell division that produces the special haploid cells called gametes. In
meiosis, chromosomes are randomly shuffled. As a result, the offspring of organisms that reproduce
sexually have a mixture of both parent’s genes. In humans, over 8 million genetically different
gametes are produced. This variety contributes to the adaptability, and therefore survival, of a species.
In this lab, you will simulate the random assortment of human genes and explore the variety of
genotypes and phenotypes that characterize the offspring.
Part A – Work with a partner. You will be simulating the random assortment of chromosomes during
meiosis. You also will be determining the possible genotype and phenotypes of the children resulting
from the union of hypothetical parents.
1. First, examine the drawings showing phenotypes for the 6 different traits. Note which traits are
dominant and which are recessive. Write your name over one of the Parent tables below. Record you
genotype and phenotype in the proper parent table. HINT: For the sake of the lab, assume that each
dominant trait is heterozygous.
2. For each chromosome, write your name, phenotype and gene (one letter) on each side. See
example.
Parent’s Name:
Parent’s Name:
Genotypes
Genotypes
Phenotypes
1.
1.
2.
2.
3.
3.
4.
4.
5.
5.
6.
6.
Phenotypes
Part B – Now you will simulate the random assortment of genes. You and your partner will have 3
children with a new combination of genes each time.
1. Cut along the dotted line surrounding each pair of chromosomes. Fold the pairs in half and
glue/tape them together.
2. Each parent should drop their chromosomes on the table (from about 1 meter high). Examine the
alleles facing up, these will be the genes the child inherits.
3. Name your child and record the genotype and phenotypes produced in the table for child 1.
4. Pick chromosomes up and repeat the procedure for child 2 and 3.
Child 1’s Name:
Genotypes
1.
Child 2’s Name:
Phenotypes
Genotypes
1.
Child 3’s Name:
Phenotypes
Genotypes
1.
2.
2.
2.
3.
3.
3.
4.
4.
4.
5.
5.
5.
6.
6.
6.
Phenotypes
1. Which step simulated the random assortment of genes that occurs during meiosis?
2. Which step simulated fertilization?
3. Identify each trait, if any, where both parents were homozygous recessive. Identify the genotype
and phenotype of the offspring. Is it possible for homozygous recessive parents to produce the
dominant phenotype?
4. Can genes be “hidden”? _____
Can traits be “hidden”? _____
5. Suppose both parents are Rr for the tongue-rolling trait. By random assortment and pairing, Predict
what traits their offspring could have if they have four children.
6. Genetic variation normally exists in a population. However, among cheetahs in eastern Africa there
is very little genetic variety. Almost the entire population has identical genes for each characteristic.
Explain why this could be a dangerous phenomenon for the population.