Download Baby Lab Instructions 1. Choosing Your Donor Bring a color

Baby Lab Instructions
1. Choosing Your Donor
Bring a color photograph or picture of your ideal gamete donor (for this project, your gamete donor
must be human and of the opposite gender!). Look in magazines, catalogs, on the internet, etc. Do not
choose a person that you personally know unless you have their permission. The photograph must be
small enough to fit inside a manila folder. The photograph must be in COLOR! The photograph must also
be appropriate!
2. Determining Phenotype
Use the Genetic Trait Guide to determine your phenotype. Record this information on the Parent
Generation Trait sheet provided. When you have determined your own phenotype, record the phenotype
of your donor. Pictures do not always show characteristics like, height. In those cases, you will have to
fill in the desired characteristic for your donor.
3. Determining Your Own Genotype
Starting with the section labeled “Simple Dominance,” determine your genotype for each trait listed
using the Genetic Trait Guide. This is one of the most important steps! Use information about your
phenotype, your parents’ phenotypes, and your siblings’ phenotypes. If you cannot determine your exact
genotype for a trait, but you know you are phenotypically dominant for the trait, choose the
heterozygous condition.
Eye and Hair Color: Polygenic Traits
For your genotype you need 2 alleles for each gene influencing color. You know that for the
recessive allele to be expressed in the phenotype, its genotype must be homozygous
recessive. For the dominant to show up, the genotype can be either homozygous dominant or
heterozygous. If you have the dominant phenotype you may choose either homozygous
dominant or heterozygous.
Example:
brown eyes - jj
could be
jj
OR
jj
K?
KK
Kk
G?
GG
Gg
S?
SS
Ss
blue eyes could be
OR
kk
kk
kk
gg
gg
gg
S?
SS
Ss
jj
jj
jj
? mark can either be a
dominant or recessive
allele.
4. Constructing Chromosomes
Use the colored sheets (pink and blue) of chromosomes provided to make a chromosome for each gene
that influences a trait for you and your donor. For the traits that involve several genes, you need to use
several chromosomes. Make certain that the sex-linked traits are placed on the X chromosomes. Because
there are several sex-linked traits, there will be several genes listed on each X chromosome. Remember
to use only one X chromosome for a male and 2 for each female. Too many or not enough X
chromosomes caused by nondisjunction lead to abnormal development!
Notice that the chromosomes come in pairs that are joined together. Meiosis has not occurred!
Therefore, the chromosome number is still diploid. To make the chromosomes, use the pink set if you
are a female, and the blue set if you are a male. Fill out one allele of each gene listed in your genotype
on one side of the chromosome in the space marked “gene.” Write the other allele for that gene on the
other chromosome in that space marked “gene.”
Example:
Dimples – Dd (1 trait, 1 gene, 2 alleles)
‘D’ goes on one chromosome in a pair
‘d’ goes on the other chromosome in that pair.
Eye color -- jj KK Gg ss (Hazel green) (1 trait, 4 genes, 8 alleles)
4 genes combine for eye color. Each one contains the alleles for each
of the 4 genes that influence eye color.
NOTE: Due to recent research we now know the actual location of some genes. For these genes (and traits),
you must use the specific chromosome indicate on the Genetic Trait Guide. Some chromosomes may have
more than one gene. In real life, chromosomes have many genes. Genes located on the same chromosomes
are called linked genes.
Continue to make chromosomes in this manor until you have assigned every allele in your genotype to
chromosome. Use the same method to construct a set of chromosomes for your donor. Use the pink set if
your donor is a female, and the blue set if your donor is a male.
5. Genetic Disorder Drawing
There is a possibility that genetic disorders run in previous generations. You will need to draw one slip of
paper from one container for your possible disorder and one slip of paper from another container for
possible disorder of your donor. There are also slips of papers that indicate no disorders present. Make sure
the two slips of paper get taped inside your folder.
NOTE (Sex-linked Disorders): Sex-linked alleles are those located on one sex chromosome but not the
other. In humans, most sex-linked alleles are located on the X chromosome (as they are in this lab). A male
(XY) only receives sex-linked alleles from his mother, since the Y chromosome is always inherited from the
father. A male therefore only needs one copy of a sex-linked recessive alleles to exhibit the trait. In
contrast, a female must inherit two copies of such recessive alleles, one from each parent, to exhibit a sexlinked trait.
When filling out the sex-linked disorders information on the chromosomes, you will need to write the
disorder genotype in addition to the genotype for baldness, since it is also sex-linked. Write your sex-linked
disorder information just under the baldness information on your parent trait sheet, to show that it is on the
same chromosome. When you code multiple sex-linked traits on your chromosomes, you will need to just
write one X, and put commas to separate the superscripts representing different sex-linked conditions
(example: Xb, c).
6. Preparing for Fertilization
Cut out each pair of chromosomes on the broken lines only. The chromosome number is still diploid. To
make gametes, you must reduce the chromosome number by ½. To do this, fold each pair of chromosomes
along the middle line so the genes are on the outside. The folded chromosome now represents a single
chromosome. The cells are now haploid gametes. Which gene will appear in the gamete? That is determined
only by probability, like tossing a coin. Gather all of your chromosomes and give them a toss in the air.
Record all the alleles that land face-up on the F1 Generation sheet Child #1. Collectively they represent the
alleles present in the gamete for you. (Note: Do not lose them. You will need your chromosomes again
later). Repeat this procedure using your donor’s chromosomes to determine the alleles present in their
gamete.
Fertilization – Simply combine the alleles from the two gametes to determine the genotype
of your child. Use the Genetic Trait Guide to determine the phenotype of your first child.
7. Second Child
Toss both sets of chromosomes again and repeat steps of fertilization. Record all the alleles that land faceup on the F1 Generation sheet Child #2. Congrats on your family!
8. Picture For The Paper
Now that you have the phenotypes in place for both children, the citizens of your community would love to
see them. Use the Face Template sheets provided to give us a peek at your lovely children. We are in the
age of color photographs, so colored pencils or markers are mandatory. Do your best—you will be graded on
effort!
9. Save Those Chromosomes!!
Place your chromosomes in a zip-lock bag. These will be turned in with all your paperwork at the end of the
unit.