The Genetics of BLOOPS
In this activity, you will be building “BLOOPS” based on genetic information that you
will gather and decode. “What are BLOOPS?” you ask. BLOOPS are friendly little
creatures that are excellent for studying genetics.
What is genetics? Genetics is the scientific study of how physical, biochemical, and
behavioral traits are transmitted from parents to offspring. The Augustinian monk
Gregor Johann Mendel formulated the basic principals of genetics. Between the
years 1856 and 1863, Mendel cultivated and tested over 28,000 pea plants, focusing
on seven pairs of characteristics or traits. Some of the seven traits were plant stem
height, flower color, seed color, and pod texture. He published his findings in 1866,
but his work was not appreciated at the time. Mendel died on January 6, 1884, long
before the significance of his work was realized and appreciated by other biologists
in the late 1920’s and early 30’s.
Mendel’s initial observations led him to coin two terms still used in present-day
genetics: dominant, for the trait that shows up in an offspring; and recessive, for a
trait that is hidden by a dominant gene. Mendel discovered that by crossing tall and
dwarf pea plants as parents, for example he got hybrid offspring that resembled the
tall parent rather than being a medium-height blend of both the tall and dwarf
parents. To explain this he conceived of hereditary units that he called “elemente,”
now called genes. Mendel stated that genes normally occur in pairs in most body
cells, but segregate during the formation of sex cells (eggs or sperm). When the egg
and sperm unite during fertilization, reforming a gene pair, the dominant gene (such
as tallness in the case of pea plants) masks the recessive gene.
Soon after Mendel’s work was rediscovered, scientists realized that the patterns of
inheritance he has described paralleled the action of chromosomes in dividing cells.
Based on this, geneticists hypothesized that chromosomes carry the Mendelian units
of inheritance. The union of gametes brings together two sets of chromosomes, one
set from each parent; therefore two genes called alleles usually represent each trait.
When the two alleles are identical, the individual is said to be homozygous
(purebred) for that particular trait. When the two alleles are different, the
individual is said to be heterozygous (hybrid) for the trait.
A distinction is made between the appearance, or outward characteristic, of an
organism and the alleles it carries. The observable, physical traits represent the
organism’s phenotype. The combination of genes is called the genotype. In
humans for example, the ability of a person to form pigment in the skin, hair, and
eyes depends on the presence of a dominant allele (A), whereas the lack of this
ability is caused by the recessive allele (a). As a result of the interaction of dominant
and recessive genes, individuals with the homozygous genotype (AA) and the
heterozygous genotype (Aa) produce normal pigmentation which is their
phenotype, while individuals with the homozygous genotype (aa) lack
pigmentation leading to the phenotype albinism. A single letter usually
designates alleles; the dominant allele is represented by the uppercase and
the recessive allele is represented by the lowercase letter.
If you know the genotype of the parents, it is possible to predict the likelihood of an
offspring inheriting a particular phenotype. Predicting the likelihood of an
offspring’s phenotype involves the concept of probability. Probability means the
chance that a given event will occur. Probability is usually expressed as a fraction,
percent, or ratio.
In genetics, the probability of a particular phenotype appearing in an offspring can
be determined by visualizing how the genotypes of the parents might interact to
generate the possible genotypes of the offspring. Such interactions are called
crosses. Punnett squares charts are often used to show the offspring genotypes
that are possible. R. C. Punnett, who devised the chart, was a British mathematician
and biologist.
Now, complete the Vocabulary Review sheet before you continue. After every
member of your lab group has completed the Vocabulary Review sheet, get a lab
sheet from Ms. Sullivan.
The Genetics of BLOOPS
OBJECTIVE: Determine the genotype and phenotype of the BLOOP.
 Eye color bead
 Antennae color bead
 Tail shape bead
 Wing bead
 BLOOP parts
1. Copy the following charts into your Science Notebook:
DATA TABLE 1: BLOOP Gene Information
Gold Eyes (DOMINANT)
Red Antennae (DOMINANT)
Straight Tail (DOMINANT)
Wings present (DOMINANT)
Silver Eyes (RECESSIVE)
Green Antennae (RECESSIVE)
Curly Tail (RECESSIVE)
Wings absent (RECESSIVE)
DATA TABLE 2: BLOOP Gene Information
Genes From the
Paternal Chromosome
(bead color and symbol)
Genes From the
Maternal Chromosome
(bead color and symbol)
Part One: Determining BLOOP’S Genotype:
2. Send one person to the “paternal genes” station. Without looking into the
bags, pick one bead from each of the four bags marked “paternal genes.”
3. Send one person to the “maternal genes” station. Without looking into the
bags, pick one bead from each of the four bags marked “maternal genes.”
4. Connect the four “paternal” beads in the following order to make a simple
BLOOP chromosome: eye color bead, antennae color bead, tail shape bead,
wing bead. This represents a chromosome that your BLOOP would inherit
from its father.
5. Connect the four “maternal” beads in the following order to make a simple
BLOOP chromosome: eye color bead, antennae color bead, tail shape bead,
wing bead. This represents a chromosome that your BLOOP would inherit
from its mother.
6. Place the two chromosomes side by side, making sure that the beads for each
trait line up next to each other. Refer to Table 1 to determine the genotype
for each of the four traits represented by the various bead color
7. In your notebook, fill in the first three columns of Table 2.
Part Two: Determining BLOOP’S Phenotype:
1. Based on the genotypes that you generated for each trait in Part One,
determine the corresponding phenotype for each trait. Keep in mind that
some traits are dominant and some traits are recessive. Fill in the
phenotype column in Table 2.
2. Based on the phenotype, obtain the appropriate parts for your BLOOP and
begin to assemble. When you have completed your BLOOP, raise your hand
to have your BLOOP checked.
Part Three: Punnett squares and probability:
Humans and BLOOPS follow the same basic rules of genetics. In BLOOPS, green
eyes are dominant, while red eyes are recessive. In humans, brown eyes are
dominant, while blue eyes are recessive. Juan and Tina have just gotten married.
They want to predict the eye color of their future children. Both Juan and Tina have
brown eyes and both are heterozygous for their brown eyes. Here’s how they can
predict their children’s eye color:
1. In your notebook, draw a box with 4 squares:
2. Using the letters “b” and “B” as the symbols for eye color, write Juan’s two
alleles (genes) for eye color across the top of the chart and Tina’s alleles
(genes) for eye color along the side of the chart. (See below)
3. Now fill in the four boxes with an allele from each parent. Each box should
contain two letters and shows the different combinations of genes that can
show up in their children.