I. Dominance, Allelic Series, and Epistasis

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BIO208 Pedigree Analysis and Allelic Series Name ______

I. Dominance, Allelic Series, and Epistasis

COAT COLORATION AND PATTERNING GENES IN CATS

LOCUSGENOTYPESNOTES

WW-wwThe whole coat is white.

all white not all whiteWhite is not the same as

albino which is recessive

BB-bb

blackbrownEumelanin pigment

(seal)(chocolate)

CC-cscscscs = Coat color with points full color Siamese Mask on face, legs, tail

DD-ddwith B- = blue (gray)

intense colordilute colorwith bb = lilac

with Oo = cream

AA-aa

agouti (tabby)non-agouti

(solid color)

SS-ss

White spottingno white spottingCat has patches of white

(absence of color) that mask the true color

OXOXoO is x-linked

orangenon-orange

XOXO(orange female)

O is epistatic over other color genesXO Xo(torti females)

except whiteXo Xo (non-orange female)

XO Y (orange male)

Xo Y (non-orange male)

BIO 208 Genetics2007

Challenge 1

Complete the following table.

GenotypeSexPhenotype

wwBBCCDDaaXo Xo______

wwbbcscsDDaaXo Y ______

wwBBCCDDAAXo Xo______

wwbbCCddaaXo Y ______

Challenge 2

Mate a chocolate,(Dd) Siamese, tabby, (AA) female with a lilac, solid color, male homozygous for all trait. What are the genotypes and phenotypes of the progeny and what proportions are expected? (do not include the O gene)

Challenge 3

A female lilac of genotype ww bb CC dd aa produced a litter of four kittens:

1 black kitten, 1 blue kitten, 1 brown tabby, 1 lilac tabby

1. What were the genotype and the phenotype of the father?

1. Could these parents produce a lilac (same phenotype as the mother?) Show your work.

II. Pedigree Analysis

Pedigree Symbols

1. A man who haspointed ears came to the attention of a geneticist. The human geneticist does a pedigree analysis and finds thefollowing:

In this family, pointy ears prove to be an inherited trait due to a single genetic locus. The man's one sister also haspointed ears, but his mother, father, his brother, and othe sisterhavenormal ears. The man and his normal-eared wife are first cousins and have seven children, including four boys and three girls. Two girls and two boys havepointy ears, the two boys are identical twins.

(a) Draw the pedigree

(b) How might pointy ears be inherited? Explain.

1. Asparagus officinalis(asparagus)is a member of the lily family and popular vegetable to grow and eat. A pungent urinary odor produced within a few hours of eating asparagus has been shown to be due to sulphur-containing metabolic breakdown products, or S-methyl thioesters . The smell cannot be noticed in raw or cooked asparagus. The odor is often described as that of boiled cabbage or ammonia.

About 40% of the population can detect S-methyl thioesters . Interestingly all people produce the thioesters, it is the ability to smell them that is inherited. Those who are able to detect the odor in their own urine can smell it in the urine of anyone who has eaten asparagus.Asparagus is also low in fat, cholesterol, and sodium, but rich in fiber, potassium, thiamine, vitamins A, C, and B6, and glutathione, a powerful antioxidant - so keep eating.

Pedigree of the ability to detect S-methyl thioesters

(a)Is the ability to detect S-methyl thioesters inherited as a dominant, or as a recessive, trait? How do you know (which individuals inform you about the inheritance)?

(b)Label the genotypes of all individuals on the pedigree

(c)Explain how individuals III,1 and III, 6 could have a non-smeller child

1. Alkaptonuria is a rare genetic disease in which the body doesnot have enough of the enzyme homogentisic acid oxidase (HGAO). Because normal amounts of the HGAO enzyme are missing, homogentisic acid (HGA) is not used and builds up in the body. Some is eliminated in the urine and if left standing for several hours will turn brownish black. The rest of the pigmented material is deposited in body tissues where it is toxic. Patients with alkaptonuria are usually not aware of the disease until about age 40 when symptoms are present.Dark staining of the diapers sometimes can indicate the disease in infants, but usually no symptoms are present until much later in life. Alkaptonuria affects many body systems:

• Skeletal –knees and hips most affected. Deposits of pigment cause brittle cartilage
• Cardiovascular - The aortic and mitral heart valves are most affected. Pigment (orchronotic) deposits also can lead to the formation of atherosclerotic plaques
• Genitourinary- Pigment deposits can form stones in the prostate.
• Respiratory- Pigment deposits in the cartilage of the larynx, trachea, and bronchi.
• Ocular - Vision is not usually affected, but there is pigmentation in the white part of the
• Cutaneous (skin)-Skin takes on blue-black speckled discoloration. Sweat stains clothes brown.

Diets low in protein--especially in phe and tyr--help reduce levels of HGA, thereby lessening amount of pigment deposited in body tissues. There is no cure. However, patients may have a normal life span and die of causes comparable to those of general population. The gene for alkaptonuria (ALK) is on human chromosome 9 and is linked to gene encoding the ABO blood group. A pedigree of a family with the disease is shown below, affected individuals indicated in black. In addition, the blood type of family members is given.

The 2 alleles at the ALK locus are denoted ALK+ and ALK-. The 3 alleles at the ABO blood group locus will be denoted IA,IB (co-dominant) and i (recessive to IA and IB).

(a) What is the genotype of individual 1 at the ALK and ABO loci?

(b) What is the genotype of individual 2 at the ALK and ABO loci?

(c) What is the genotype of individual 3 at the ALK and ABO loci?

(d) Individuals 3 and 4 are expecting their fifth child. A physician draws a prenatal blood sample. What is the probability that the child will have alkaptonuriaAND type B blood? Explain your answer.

FELINE GENETICS, COLORS & PATTERNS

THE SOLID COLORS

Non-agouti, or self-colored cats can also be called "solid" cats. When the cat's body and fur are entirely one color, with no flecks of another color, we can refer to them as "solid" colored cats. Solid cats come in seven colors: black, chocolate, cinnamon, white, blue, lavender and fawn. Only the first four colors listed are the true solid colors, and the latter three are referred to as "dilute colors", which means that they are lighter versions of the solid. Blue is the dilute of black; lavender is the dilute of chocolate, fawn is the dilute of cinnamon.

• BLACK: With black cats, the hairs are solid black from base to tip.

• CHOCOLATE: Brown, or chocolate, is often seen as a base color, but rarely as a solid color cat (except in breeds like the Burmese).

• WHITE: White is actually the ABSENCE of color, at least in cats, and is similar to an albino animal. White cats often have blue eyes, and blue-eyed white cats may be deaf in many cases. Occasionally, a white cat may have one green eye and one blue eye. These cats are often deaf in the ear which corresponds to the blue eye. The white cat cannot make the pigment which causes the coat color. White is sometimes referred to as "dominant white", as the white coloration gene masks or covers up all other colors! Underneath each and every white cat is a different color cat with all the genes necessary for other coat colors and patterns; however, the white gene has suppressed them (dominated them).

THE DILUTE COLORS

• BLUE: Blue cats are dilute examples of black cats, and are sometimes (erroneously) referred to as "grey" cats.

• LAVENDAR: You will hear lavender sometimes referred to as "lilac". The lavender cat is a frosty grey-brown that actually does have a lavender tint in certain lights.

THE TABBY COLORS

The cream tabby starts with cream-colored spots or stripes with a much paler shade of cream in between. The color of the cream tabby is determined by the darker markings, not by the lighter color between them.

The red tabbies are most often a deep, rich orange; however, some mixed-breed cats can actually be more of a faded "marmalade" or "ginger" color. The red tabby color can range from light peach to the wild, bright orange of Garfield the Cat. Cream -- the dilute of red -- has a peach hue.

The brown tabby is actually a solid black cat -- except, of course, for the lighter color in between the black stripes, which in this case is brown.

The blue tabby has a blue-grey color between the stripes or spots of dark, slate-blue markings.

The ticked tabby's color is determined, instead, by the darkest color of the tipping. Markings, not the "base" color, determine the coat color of ticked tabbies.

THE TABBY PATTERNS

"Tabby" actually refers to the pattern of a cat, and is less about the stripes on the cat than about the stripes that may appear on each individual hair on the cat. If you look closely at the light colored hairs on a spotted or striped cat, you will see a mottled or even a freckled appearance (ticking) which form the yellow bands of color between the spots or stripes. When you look at the hairs in the darker areas of the spots or stripes on the cat, this ticking appears to be absent All tabbies can be identified by the single "M" marking on their foreheads. There are four tabby patterns: Ticked, Mackerel, Classic and Spotted.

TICKED TABBY The ticked tabby is covered with individually banded hairs. The coat of a ticked tabby will appear to shimmer or glow, as the underlying coat is a different color than the darker tip on each individual hair.

MACKEREL TABBY:The mackerel tabby is covered with thin stripes and rings, which reminded someone of the striped pattern of mackerel fish, which is where the name came from. This is the cat with the familiar tiger cat coat pattern.

CLASSIC TABBY:Persians, Maine Coons, American Shorthairs...these are just a few popular breeds that are classic tabbies. This classic pattern has wide bands of dark color forming large rosettes or bull's-eyes on the cat's sides, and also a common marking known as a butterfly marking on the shoulder area. The pattern is dramatic and very popular. Outside of North America, you will hear this pattern referred to as "Blotched".

CALICOS, TORTOISESHELLS & TORBIES

The basic story of the tortoiseshell and calico patterns has to do with the nature of the red color gene. To be identified as tortoiseshell or calico, the cat must show both red and one of the three non-red colors (black, chocolate/brown or cinnamon). The most common tortoiseshell or calico combination is black and red. A calico cat will have a substantial amount of white, and red and black will form distinct patches. On a tortoiseshell cat, the red and black swirl together, with few if any patches. When the tortoiseshell (sometimes called "tortie") and tabby markings are mixed, you will have a torbie, also known as a patched tabby .

THE POINTED PATTERN

The pointed pattern refers to the pattern wherein the extremeties of the cat are a different (i.e., darker) color than the rest of the animal. The Siamese Cat is usually considered the probable origin or ALL the pointed cats in the United States. What are the "points"? The face, legs and tail. There are four basic Siamese colors: Seal (basically, black); Chocolate, Blue, and Lilac. Red, cream, tortoiseshell and lynx point can also occur in the pointed pattern.

In the lynx point cat, the cat has tabby markings (often mackerel tabby) on the face, tail and legs, and the distinctive "M" on the forehead. In most other pointed cats, the colored points are solid. In fact, Burmese, which are bred to appear solid color in appearance, are actually color points. Tonkinese cats, which have one of the Siamese-type color point genes and one of the Burmese-type color point genes, can give us the lovely mink color, which is created with wonderful, very mild shades of color pointing.