Name: ____________________
Date: _______________
Period: ______
Baby Lab
Pre-Lab Discussion
Heredity is the passing on of traits, or characteristics, from parent to offspring. The units of
heredity are called genes. Genes are found on the chromosomes in a cell. The combinations of genes
for each trait occur by chance.
When one gene in a pair is stronger than the other gene, the trait of the weaker gene is masked,
or hidden. The “stronger” gene is the dominant gene, and the gene that is masked is the recessive
gene. Dominant genes are written as capital letters and recessive genes are written as lowercase
letters. If both genes in a gene pair are the same, the trait is said to be homozygous, or purebreeding. Sometimes genes are neither dominant nor recessive.
The genetic makeup of an individual is known as its genotype. The observable physical
characteristics of an individual that are the result of its genotype are known as its phenotype. In
humans, the sex of an individual is determined by the particular combination of the two sex
chromosomes. Individuals that have two X chromosomes (XX) are females, whereas those with an X
and a Y chromosome (XY) are males.
In this investigation, you will observe how the results of different gene combinations produce
certain traits.
Problem
How are traits inherited?
Procedure
1. Each partner must pick up one coin.
2. You will flip the coin and write down the genotype.
3. Using the parents’ genotypes, complete a Punnett square when asked, and also record the
genotype and phenotype ratios for each Punnett Square.
4. You now must now form your egg and sperm. For each chromosome, each parent will flip
their coin and if they get head it will be the dominant allele if they flip tails it will be recessive.
5. The alleles from each pair of chromosomes will be recorded in the data chart, recorded as the
baby’s genotype.
6. The decoding chart on page 2 indicates the phenotype of each gene. Use the chart to find the
phenotype produced by your pair of alleles and record it in the data chart as the baby’s
phenotype. Remember that a CAPITAL letter is dominant over a small letter [recessive] unless
the decoding chart indicates those traits are incomplete dominance.
7. Continue to flip the coin for each chromosome. After each flip, record your offspring’s new
genotypes and phenotypes in the table.
Human Baby Genome
Decoding of the Genes
Chromosome
Dominant Genes
Recessive Genes
Autosome #1
R. Round Face
H. [See Below]
r. Square Face
Autosome #2
G. Widow’s Peak
E. [See Below]
g. No Widow’s Peak
Autosome #3
A. Almond Eyes
L. Long Eyelashes
a. Round Eyes
l. Short Eyelashes
Autosome #4
N. [See Below]
Autosome #5
T. [See Below]
Austosome #6
F. Freckles
f. No Freckles
Autosome #7
B. [See Below]
D. Dimples
d. No dimples
Incomplete Dominance Traits
HH. Curly Hair
EE. Eye close together
NN. Large Nose
TT. Thick Lips
BB. Large Ears
Hh. Wavy Hair
Ee. Eyes medium distance
Nn. Medium Nose
Tt. Medium-sized Lips
Bb. Medium Ears
hh. Straight Hair
ee. Eyes far apart
nn. Small nose
tt. Thin lips
bb. Small ears
Data Tables:
Autosome #1
Genotype
of Mom
Phenotype of
Mom
Genotype
of Dad
Phenotype of
Dad
Genotype of
Baby
Phenotype of
Baby
Draw a Punnett Square for Shape of Face, and record the genotype and phenotype ratios possible for
the offspring:
EXAMPLE!!!
R
R
Genotype Ratio:
2RR : 2Rr
Phenotype Ratio:
4 round : 0 Square
R
RR
RR
r
Rr
Rr
Draw a Punnett Square for Texture of Hair (curly vs. wavy vs. curly), and record the genotype and
phenotype ratios possible for the offspring:
Autosome #2
Genotype
of Mom
Phenotype of
Mom
Genotype
of Dad
Phenotype of
Dad
Genotype of
Baby
Phenotype of
Baby
Draw a Punnett Square for Widow’s Peaks, and record the genotype and phenotype ratios possible for
the offspring:
Autosome #3
Genotype
of Mom
Phenotype of
Mom
Genotype
of Dad
Phenotype of
Dad
Genotype of
Baby
Phenotype of Baby
Draw a Punnett Square for Shape of Eyes, and record the genotype and phenotype ratios possible for
the offspring:
Autosome #4
Genotype
of Mom
Phenotype of
Mom
Genotype
of Dad
Phenotype of
Dad
Genotype of
Baby
Phenotype of Baby
Genotype
of Dad
Phenotype of
Dad
Genotype of
Baby
Phenotype of Baby
Autosome #5
Genotype
of Mom
Phenotype of
Mom
Draw a Punnett Square for Shape of Lips, and record the genotype and phenotype ratios possible for
the offspring:
Autosome #6
Genotype
of Mom
Phenotype of
Mom
Genotype
of Dad
Phenotype of
Dad
Genotype of
Baby
Phenotype of
Baby
Genotype
of Dad
Phenotype of
Dad
Genotype of
Baby
Phenotype of
Baby
Genotype
of Dad
Phenotype of
Dad
Genotype of
Baby
Phenotype of
Baby
Autosome #7
Genotype
of Mom
Phenotype of
Mom
Sex Chromosomes
Genotype
of Mom
Phenotype of
Mom
Draw a Punnett Square for the sex of a possible baby, and record the genotype and phenotype ratios
possible for the offspring:
Observations
Sex of offspring: ___________________
Drawing of offspring (draw head only):
Trait
Shape of
Face
Texture of
hair
Widow’s
Peak
Spacing of
eyes
Shape of
eyes
Length of
Eyelashes
Size of nose
Size of Lips
Freckles
Size of Ears
Dimples
Phenotype of
Baby
Name: ____________________________
Baby Lab Questions
Data Analysis and Conclusions
1. What is the probability (in percent) of “producing” a male offspring? A female offspring?
2. Every pair in your class had the same female and male chromosomes for your “parents.”
Would you expect the other pairs of students in your class to have an offspring similar to
yours? Explain your answer?
3. If a woman who is homozygous for almond-shaped eyes (AA) marries a man who is
heterozygous for almond-shaped eyes (Aa), what are the possible genotypes and phenotypes of
their children?
4. You worked with traits that are called “incomplete dominance.” By looking at what occurs
with the trait, what do you think that means? Provide evidence from the lab to support your
claim.
Critical Thinking and Application
5. Do you think that anyone in your class has all the same genetic traits that you have? Explain
your answer. (YOU, and not your baby!)
6. Do you think you would have some genetic traits similar to your grandparents? Explain your
answer. (YOU, and not your baby!)
Extra Credit
7. How might it be possible for you to show a trait when neither of your parents shows it?