Assignment 1 IntroductionChapter 1. Cat Coat Exercise
Genetics is concerned with the mechanisms whereby traits are passed from parent to offspring. Thesegenes code for a genotype which code for a specific trait. An allele is an alternate form of gene found atthe same gene location. A phenotype is the trait that you can observe. For example, a person’s phenotypewould be the particular hair color. The genotypes are the genes that code for the phenotype. Some genesare dominant, meaning that the gene is expressed in all offspring carrying that gene. Other genes arerecessive, and their effects are not expressed unless they occur together with the same recessive gene onthe 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 tothat 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 agood source for cat pictures). You will be describing the hair traits of your three cats. While there aremore genes that determine coat color than the five in this exercise, most animals can be described quitewell with these. If you want to learn more about cat coat genetics, there are many sources of informationon 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 Examples1. 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 ispossible for two short-hair cats to have a long-hair offspring (if the genotype of each parent was theheterozygous Ll), it is impossible for two long-haired cats to have a short-hair offspring (both genotypesare the homozygous recessive ll).
Genotype: LL or LlPhenotype: short hairGenotype: llPhenotype: 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 ishomozygous 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 Siamesecat further in this exercise on the C gene) and results in true albinism. Since the dominant form of thistrait masks all other cat coat genes, if a cat is totally white, you cannot determine the forms of thespotting, pigment density, or orange genes to follow.
Genotype: WW or WwPhenotype: All whiteGenotype: wwPhenotype: 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 canbe extensive in homozygous dominant cats (SS) such that the cat is mostly white, somewhat lessextensive in heterozygous ones (Ss), and absent in homozygous recessive cats (ss).
Homozygous dominant (SS)Genotype: SSPhenotype: Mostly whiteHeterozygous (Ss)Genotype: SsPhenotype: Large colored areasHomozygous recessive (ss)Genotype: ssPhenotype: No white
4.Pigment density (D)Cats have a gene that determines how much color pigment is present in the coat. Animals with thedominant phenotype (D) have darker fur than those with the recessive phenotype (d). Cats with DD or Ddhave black, brown, or orange coats; cats with dd have gray, tan, or cream coats.
Genotype: DD or DdPhenotype: Dark furGenotype: ddPhenotype: 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 isconsidered X-linked. This means there is a pattern of coloration that is unique to female cats- theheterozygous calico or tortoiseshell (Oo) which has a mix of orange-tinted and colorless hair. Cats withonly dominant alleles (OO females, or O- males) are orange or cream (no dark colors), while cats withonly 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 pigmentsHeterozygous phenotype(Oo)Genotype: Oo (F only)Phenotype: Orange and blackRecessive 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 fitneatly into the above five traits. The cat has white, tan, and black areas, along with blue eyes in manyindividuals in this breed. This is because Siamese cats have a dark coat gene mutation (cs) that is activeonly where the body temperature is lower (called temperature-sensitive albinism). These areas include theface, ears, legs, and tail. The gene is unable to function on the warmer body of the cat, which is muchlighter (and can be white). If you put this cat into a very warm environment at a very early age, the cat’sfur would be mostly white. The reason this breed also has blue eyes is that the gene involved (C) normallyresults 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 foundin all albino organisms (cc, right photo).Data CollectionCollect the data that you generated by looking at the 5 different hair genes in your three cats. Use thistable to generate class percentages for each trait. Since you cannot determine your cat’s phenotype (in thecase of an all-white cat), you might want to select a cat that is not all white.Table 1
Gene Dominantphenotype(allele)Recessivephenotype(allele)Cat 1phenotype andgenotype(alleles)Cat 2phenotype andgenotype(alleles)Cat 3phenotype andgenotype(alleles)Hair length Short(L)Long(l)White masking[If your cat is allwhite, stop here!]All white(W)[STOP]Some color(w)[Do nextthree]Piebald/White spottingPatches ofwhite (S)No whitepatches(s)Pigment density Dark-black,brown ororange(D)Light-gray,tan or cream(d)Orange/red furvariations(X-linked)Orange,cream(OO femaleor 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 OOASSIGNMENT 1After completing the table for your three cats, answer the questions in the Week 1/2 overview. They arereproduced 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 followingquestions.a. What was the genotype and phenotype of each cat that you found on Petfinder (threetotal)? Be sure to include all letter groups for genotype, and all phenotype descriptions. Ifpossible, it would be helpful if you copied and pasted the picture of each cat from thewebsite 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 thiscat 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 differentneurons involved in a reflex. [3 points]b. Explain the steps of a synaptic event, and how neurotransmitters might be removed fromthe cleft. [5 points]c. For three neurotransmitters of your choice, describe the symptoms that someone mightexhibit if that neurotransmitter is out of balance. Consult Table 2.2 if necessary [3 points]
The post Cat Coat Exercise Assignment Help-What was the genotype and phenotype of each cat that you found on Petfinder (three total)? .
Assignment status: Solved by our experts