Cat Coat Exercise Assignment Help-What was the genotype and phenotype of each cat that you found on Petfinder (three total)?

Assignment 1
Introduction
Chapter 1. Cat Coat Exercise

Genetics is concerned with the mechanisms whereby traits are passed from parent to offspring. These
genes code for a genotype which code for a specific trait. An allele is an alternate form of gene found at
the same gene location. A phenotype is the trait that you can observe. For example, a person’s phenotype
would be the particular hair color. The genotypes are the genes that code for the phenotype. Some genes
are dominant, meaning that the gene is expressed in all offspring carrying that gene. Other genes are
recessive, and their effects are not expressed unless they occur together with the same recessive gene on
the other chromosome. An individual is homozygous for a trait if the two alleles are identical (GG or gg),
and heterozygous if the two alleles are different (Gg).
If you have ever had a cat, you might have noticed that the color, patterning, and shading was unique to
that pet. Despite the large number of breeds of cats in the world, from Abyssinian to York Chocolate,
there are five major genes that determine the overall color, pattern, and length of hair on domestic cats
(Felis catus).
Either look at a picture of your own cats, or find three on a pet adoption website (www.petfinder.com is a
good source for cat pictures). You will be describing the hair traits of your three cats. While there are
more genes that determine coat color than the five in this exercise, most animals can be described quite
well with these. If you want to learn more about cat coat genetics, there are many sources of information
on the web and at your local library.
Note: All pictures of cats were taken from a local search on http://www.petfinder.com.
Genes and Examples
1. Hair length (L)
The L gene in cats determines the overall length of each strand of hair in the cat. A dominant allele (L)
results in a short-haired cat coat, while a recessive allele (l) results in a long cat coat. Therefore, while it is
possible for two short-hair cats to have a long-hair offspring (if the genotype of each parent was the
heterozygous Ll), it is impossible for two long-haired cats to have a short-hair offspring (both genotypes
are the homozygous recessive ll).

Genotype: LL or Ll
Phenotype: short hair
Genotype: ll
Phenotype: long hair

2. White masking (W)
This gene controls the expression of color pigments in the cat fur. If the dominant allele (W) is present,
even in the presence of the recessive allele, the cat is completely white with no color anywhere on the cat
(this is not an albino cat- just one with white fur). If there is any colored fur on the cat, then it is
homozygous recessive (ww). A cat with the dominant phenotype (white) will have yellow or blue eyes
(and can have both, like the cat below). If a cat has pink eyes, this is due to a different gene (see Siamese
cat further in this exercise on the C gene) and results in true albinism. Since the dominant form of this
trait masks all other cat coat genes, if a cat is totally white, you cannot determine the forms of the
spotting, pigment density, or orange genes to follow.

Genotype: WW or Ww
Phenotype: All white
Genotype: ww
Phenotype: Some colored fur

3. White-spotting/Piebald (S)
Some cats have spots of white on their fur, with the rest of their coats being normal color. These spots can
be extensive in homozygous dominant cats (SS) such that the cat is mostly white, somewhat less
extensive in heterozygous ones (Ss), and absent in homozygous recessive cats (ss).

Homozygous dominant (SS)
Genotype: SS
Phenotype: Mostly white
Heterozygous (Ss)
Genotype: Ss
Phenotype: Large colored areas
Homozygous recessive (ss)
Genotype: ss
Phenotype: No white

4.
Pigment density (D)
Cats have a gene that determines how much color pigment is present in the coat. Animals with the
dominant phenotype (D) have darker fur than those with the recessive phenotype (d). Cats with DD or Dd
have black, brown, or orange coats; cats with dd have gray, tan, or cream coats.

Genotype: DD or Dd
Phenotype: Dark fur
Genotype: dd
Phenotype: Light fur

5. Orange pigments (O)
Unlike the previous four genes, this one is found on the X chromosome in cats, and therefore this trait is
considered X-linked. This means there is a pattern of coloration that is unique to female cats- the
heterozygous calico or tortoiseshell (Oo) which has a mix of orange-tinted and colorless hair. Cats with
only dominant alleles (OO females, or O- males) are orange or cream (no dark colors), while cats with
only recessive alleles (oo females or o- males) have black or gray coats (no orange).

Dominant phenotype (OO or O-)
Genotype: OO (F), O- (M)
Phenotype: Orange pigments
Heterozygous phenotype(Oo)
Genotype: Oo (F only)
Phenotype: Orange and black
Recessive phenotype(oo or o-)
Genotype: oo (F) or o- (M)
Phenotype: Black or gray

Side notes: The interesting case of the Siamese cat and temperature-sensitive albinism.

Temperature sensitive albinism (cscs) True albino cat (cccc)

You might have wondered why the Siamese cat has its distinctive coloration pattern, which doesn’t fit
neatly into the above five traits. The cat has white, tan, and black areas, along with blue eyes in many
individuals in this breed. This is because Siamese cats have a dark coat gene mutation (cs) that is active
only where the body temperature is lower (called temperature-sensitive albinism). These areas include the
face, ears, legs, and tail. The gene is unable to function on the warmer body of the cat, which is much
lighter (and can be white). If you put this cat into a very warm environment at a very early age, the cat’s
fur would be mostly white. The reason this breed also has blue eyes is that the gene involved (C) normally
results in the production of refractory pigments in the iris (causing what is called Rayleigh scattering,
which also is what causes the sky to look blue). True albino cats have the distinctive pink eye color found
in all albino organisms (cc, right photo).
Data Collection
Collect the data that you generated by looking at the 5 different hair genes in your three cats. Use this
table to generate class percentages for each trait. Since you cannot determine your cat’s phenotype (in the
case of an all-white cat), you might want to select a cat that is not all white.
Table 1

Gene Dominant
phenotype
(allele)
Recessive
phenotype
(allele)
Cat 1
phenotype and
genotype
(alleles)
Cat 2
phenotype and
genotype
(alleles)
Cat 3
phenotype and
genotype
(alleles)
Hair length Short
(L)
Long
(l)
White masking
[If your cat is all
white, stop here!]
All white
(W)
[STOP]
Some color
(w)
[Do next
three]
Piebald/
White spotting
Patches of
white (S)
No white
patches
(s)
Pigment density Dark-black,
brown or
orange
(D)
Light-gray,
tan or cream
(d)
Orange/red fur
variations
(X-linked)
Orange,
cream
(OO female
or O- male)
Calico,
tortoiseshell
(Oo female)
Black or gray
(oo female)
(o- male)

Note- when reporting genotypes for homework, be sure to include ALL traits together, as follows:
• Phenotype: short hair, some color, patches of white, light orange and tan cream female
• Genotype: L? ww S? dd OO
ASSIGNMENT 1
After completing the table for your three cats, answer the questions in the Week 1/2 overview. They are
reproduced below. NOTE- you DO NOT need to submit the filled in table with your homework.
1. Download the Assignment1_Ch1_CatCoatExercise.pdf handout and answer the following
questions.
a. What was the genotype and phenotype of each cat that you found on Petfinder (three
total)? Be sure to include all letter groups for genotype, and all phenotype descriptions. If
possible, it would be helpful if you copied and pasted the picture of each cat from the
website into your submission. [6 points]
b. If a cat is all white, why are you unable to give a genotype past white masking? [1 points]
c. You see a cat that is calico (coat contains black, white, and orange fur). What sex must this
cat be, and why? [2 points]
2. Answer the following questions, in your own words:
a. Briefly (in 3 sentences or less), name and describe the functions of the three different
neurons involved in a reflex. [3 points]
b. Explain the steps of a synaptic event, and how neurotransmitters might be removed from
the cleft. [5 points]
c. For three neurotransmitters of your choice, describe the symptoms that someone might
exhibit if that neurotransmitter is out of balance. Consult Table 2.2 if necessary [3 points]