Yellow color in labs is caused by variations in a different gene: MC1R. This gene controls the production of the melanocortin 1 receptor protein. MC1R is located on chromosome 5 in dogs Schmutz, Melanocytes make two forms of melanin, eumelanin and pheomelanin. Eumelanin also protects skin from damage caused by ultraviolet UV radiation in sunlight. Because pheomelanin does not protect skin from UV radiation, people with more pheomelanin have an increased risk of skin damage caused by sun exposure.
The melanocortin 1 receptor controls which type of melanin is produced by melanocytes. When the receptor is activated, it triggers a series of chemical reactions inside melanocytes that stimulate these cells to make eumelanin.
If the receptor is not activated or is blocked, melanocytes make pheomelanin instead of eumelanin.
This means that if the receptor is working correctly and is turned on, dark pigment will be produced. If the receptor is not functional or is not turned on, light pigment will be produced. Schmutz et.
They determined that black and brown dogs all have one allele of MC1R, while yellow and red dogs have a different allele. The allele that leads to yellow or red color has a premature stop codon which results in a shorter-than-normal protein.
This protein would be predicted to not function correctly. Remember that when the melanocortin 1 receptor is not functioning correctly, light pheomelanin pigment is produced and not dark eumelanin. Dogs that are homozygous for the functioning allele of MC1R which would cause eumelanin to be produced are dark in color.
Dogs that are homozygous for the non-functioning allele which would cause pheomelanin to be produced are light in color. Dogs that are heterozygous are dark in color. What does this tell you about which allele is dominant? Dogs that have the genotype EE or Ee will produce eumelanin and be dark.
Since all of the puppies resulting from this cross were black, we would predict that the first Punnett square shows the cross. However, it is possible that the second Punnett square is correct. It would be comparable to flipping a coin 4 times and getting 4 heads in a row.
Getting 4 heads in a row is less likely, but definitely possible. It is very important to note here that yellow dogs still have the TYRP1 gene, even though they are not black or brown!
Certain genetic variations are most common in people with red hair, fair skin, freckles, and an increased sensitivity to sun exposure. OpenStax, Biology. OpenStax CNX. Anim Genet. Mammalian Genome 13, Figure 1: This yellow lab is producing light-colored pheomelanin instead of dark-colored eumelanin.
Credit: Djmirko ; from Wikimedia.The allele combinations along the top and sides become labels for rows and columns within the square. Complete the genotypes in the square by filling it in with the alleles from each parent. Since all allele combinations are equally likely to occur, a Punnett Square predicts the probability of a cross producing each genotype. Number of traits in cross:.
A single trait Punnett Square tracks two alleles for each parent. The square has two rows and two columns. Adding more traits increases the size of the Punnett Square. Assuming that all traits exhibit independent assortment, the number of allele combinations an individual can produce is two raised to the power of the number of traits.
If the genes for the two traits are on the same chromosome, alleles for each trait will always appear in the same combinations ignoring recombination. With one row or column for each allele combination, the total number of boxes in a Punnett Square equals the number of rows times the number of columns.
Multi-trait Punnett Squares are large. A three trait square has 64 boxes. A four trait square has boxes. The genotype in each box is equally likely to be produced from a cross. A two-trait Punnett Square has 16 boxes. The probability of a cross producing a genotype in any box is 1 in If one of the parents is a homozygote for one or more traits, the Punnett Square still contains the same number of boxes, but the total number of unique allele combinations is 2 raised to the power of the number of traits for which the parent is heterozygous.
A commonly discussed Punnett Square is the dihybrid cross. A dihybrid cross tracks two traits. This means that both parents have recessive alleles, but exhibit the dominant phenotype. The phenotype ratio predicted for dihybrid cross is Of the sixteen possible allele combinations:. A simpler pattern arises when one of the parents is homozygous for all traits.
In this case, the alleles contributed by the heterozygous parent drives all of the variability. A two trait cross between a heterozygous and a homozygous individual generates four phenotypes, each of which are equally likely to occur. More complicated patterns can be examined. In an extreme case when more than two alleles exists for each trait and the parents do not possess same alleles, the total number of genotypes equals the number of boxes in the Punnett Square.Dog breeders carefully choose which dogs to breed from based on a number of different characteristics, such as the way it looks, its general health, its temperament, etc.
The process of passing characteristics from parent to offspring is known as inheritance, but how are these traits determined? How a dog looks and behaves is determined by a combination of the environment it lives in, the environment it has grown up in and its genetics.
A dog's genome the sum of its genetic material can be thought of as a cook book which is split into chapters containing recipes. These recipes are the dog's genes and the letters that makes up each recipe is the DNA. Just like a recipe can be used to make a dish of food, a gene can be used to make a protein. Proteins are the building blocks for ever organism and make up bones, teeth, hair, muscle, etc.
Genes are therefore vital in producing proteins which impact on a dogs characteristics. Each dog has two copies of every gene, one of which it inherited from its mother and one from its father. These two genes may be the same or they may be slightly different. Different versions of the same gene are called alleles and can cause variation in the protein that is produced, or where, when and how much of the protein is produced. When a dog has two copies of the same allele they are said to be homozygous.
When the two alleles they have are different, they are known as heterozygous. When a sperm and egg come together to form a new set of DNA, the two halves combine, so that each puppy has two copies of every gene, one inherited from its mother and one from its father.
The combination of alleles a dog has is known as the genotype. The physical characteristics a dog has in known as its phenotype. Alleles can be said to be either recessive or dominant. A recessive allele is only expressed influences the characteristics of the dog if both alleles are the same. A dominant allele on the other hand is always expressed, even if it is accompanied by a different allele.
A genetic diagram or punnett square can be used to show how dominant and recessive alleles work. Letters are used to symbolise the genotype the alleles a dog has. A capital letter represents a dominant allele and a small letter represents a recessive allele.
The example below shows a made up punnett square for coat colour with the B representing a dominant allele for brown fur and the b representing a recessive allele for blonde or yellow fur. In the example below both parents have a genotype of Bb. Since the B is dominant, then any offspring that has a Bb or BB will be brown, while offspring that has two copies of the recessive b will be yellow.
A blending of phenotypes can sometimes occur when an individual has two different alleles. Using the example in the punnett square, an individual with BB would still have brown fur, an individual with bb would still have yellow fur, but an individual with a B and a b would have a coat colour somewhere between the two.
For some characteristics two alleles can both be expressed at the same time. A good example of this is the blood type AB in humans. Individuals with type AB blood produce both type A and type B blood. These are traits that have more than two possible alleles. A dog will still only have two copies of each gene, one from each parent, but there will be a variety of possible alleles within the population.
A good example of this is once again blood type in humans, where there are three possible alleles, i Ai B or i. An individual can therefore be i A i Bi A i, i B i or ii. Having more than two alleles increases the possibilities of the phenotypic characteristics in a population. These genes influence the degree to which other genes control their characteristics. Sometimes the effect of one gene can mask the expression of another unrelated gene. Coat colour in Labrador retrievers is a good example of this.
A black coat colour allele B in Labradors is dominant, while a brown coat chocolate allele b is recessive. Despite this, a second gene found in a different area of DNA can override these and create a yellow coat.All dogs, as well as every other type of animal and plant living on Earth, are made up of living cells. Each one of these microscopic "building blocks of life" contains a specific set of "biochemical blueprints" called chromosomes.
These complex molecules not only make it possible for cells to repair and reproduce themselves, but they also "instruct" the cell what it's function is. For example, whether a cell is supposed to be part of an organ like the heart, or part of your skinor if it's role is to grow a hair on top of your head. Chromosomes themselves are made up of small building blocks called geneseach of which is responsible for influencing a single function, or traitin that cell.
When paired along the two strands of a chromosome, genes act in one of two ways. One way genes can act is in an "additive" manner i. The second way paired genes act is when one gene is dominant and the second gene is recessive : only the trait of the dominant gene is carried out, or expressedin or by the cell.
The recessive gene's trait is masked by that of the dominant gene, but is still present on the chromosome. This creates an opportunity for each gene along corresponding chromosome strands to be paired up with a corresponding gene that has a different trait variation from what it was paired with before, possibly causing the resulting offspring to have many different trait-characteristics from its parents. By the same token, an offspring's chromosomes may end up being nearly identical to one or both of the parents'.
People found out long, long ago that many traits Below is an example of a Punnett Square that was created to determine the coat color outcome in the litter of puppies produced if two cocker spaniels with black hair are bred. This breeding, or "crossing", can thus be represented mathematically by the equation Bb x Bbsince each parent dog is black B but has buff b in its recent background.
The Punnett Square is used to predict the outcome of this gene crossing by placing one of the female parent's two gene letters in the pink box above each of the two columns of the Punnett Square table, and then placing each of the male parent's gene letters in the blue box to the left of each of the two rows of the table.
Next, starting with the first row of the table, pair the letter which corresponds for that row B with the letter that corresponds with each column, and fill in each new gene pair of letters in the corresponding box for each row-column match up. Repeat this step for the second row which corresponds with the letter b. Genuine cockapoos originate from the breeding or "crossing" of a n American Cocker Spaniel of pure lineage with a French Poodle of pure lineage. Let's use what we learned above, and assign the capital letters CC to represent the gene pair for C ocker Spaniel and the capital letters PP to represent the gene pair for P oodle.
A litter of puppies produced by this "cross" is quite accurately predicted by the Punnett Square :. Although first-generation Cockapoos exhibit a "most favorable combination" of the traits characteristic of their parental breeds, they still retain those alleles variations from their parents which were not expressed in their generation. This " prediction " is proven to be true when two unrelated first-generation Cockapoos CP are bred.
Again, the Punnett Square statistical test yields a very accurate estimate of the litter composition :. Applying the three "unique" gene pairs i. When a "pure" Cocker Spaniel and a "pure" Poodle are successfully bred, the entire litter of puppies produced is composed of first-generation Cockapoos CP. They grow to become adults whose physical appearance and other traits "shares" characteristics from both parental breeds. The Punnett Square test cannothowever, take into account the selective breeding methods being used by the Cockapoo breeders truly involved in attempting to establish this "hybrid" as a recognized breed.Monohybrid Punnett Square Problems.
Incomplete dominance. Dihybrid Punnett Squares Problems. Purple flowers are dominant to white flowers. Using the allele "p", write the genotype for a white flower.Genetics of Dog Breeding
A long tailed dog L and a short tailed S dog mate to produce all medium length tailed puppies. What is the genotype of the medium length tailed puppy?
Unattached earlobes U are dominant to attached earlobes and tongue rolling T is dominant to not being able to roll tongue. The wife is homozygous dominant for unattached earlobes and heterozygous for tongue rollling. The husband has attached earlobes and is homozygous dominant for tongue rolling. Write the parents genotypes?
Tall stems are dominant to short stems. The offspring are all short stemmed. Using the allele "t", what are the genotypes of the parents? You can set the timer to 2 minutes! What is the term for the combination of alleles that parents pass to their offspring?
Using the allele "t", write the possible genotypes to represent tall stems. Long tailed dogs L and short tailed S dogs create medium length tailed puppies. What if two parents are heterozygous? What are the chances in percent that they will have a short tailed puppy? Tall stems T are dominant to short stems and round seeds R are dominant to wrinkled seeds. One parent is heterozygous for tall stems and has wrinkled seeds. What are the 4 gamete combinations for this parent. The parent's genotype is Ttrr.
Use foil or a small punnett square to get the four gamete combinations which are: Tr, Tr, tr, and tr. Long hair is dominant to short hair in cats. One parent has short hair. Using the allele "h", what is the genotype of the other parent? If one parent has short hair hhthen the other parent must be HH to always have kids that have long hair. Round seeds are dominant to wrinkled seeds. If two heterozygous round seeded plants cross, what is the probability in percent that they would have wrinkled seeded offspring?
What are the possible genotypes for offspring who has a long tailed parent and a medium length tailed parent? In rabbits, grey fur G is dominant to white fur g and black eyes B are dominant to red eyes b. One parent is GgBb and the other parent is ggBb. What is the probability in fractions that they will produce offspring that have grey fur and black eyes?Materials: Dice with evenly distributed capital and lowercase letters based on the selected traits Ee, Gg, Tt, Bb, Ll, NnDraw a dog worksheet, Punnett square practice worksheet, Punnett Square vocab worksheet, pen or pencil, color markers, large poster paper, dry erase boards for student use substitute sheet protectors for student use if dry erase boards are not availabledry erase markers, index cards with genetic terms or examples of traits, student response cards.
Use this as your introduction to traits and how animals, like people, are similar in some ways but very different in others. Tell students we are going to learn more about traits in animals and how that relates to the jobs that involve caring for and dealing with animals.
Try to guess why or how the teacher divided the class. Write their hair color, eye color, and hand dominance on an index card.
Punnett Square Calculator
Other than farmers and ranchers, careers related to veterinary care are the most popular career choice. There is also a big difference in education required for the two different professions, though.
Veterinarians are required to go to graduate school beyond their undergraduate degree, which requires admission to a graduate program and an additional four years of education. You will leave with a D. On the other hand, veterinary assistants require little if any formal education beyond a high school diploma. But before we do that, we need to figure out how animals get their individual characteristics and learn a few important terms that veterinarians, animal scientists, and others who work with animals use.
Using the completed Punnett square in the handout draw on the big dry erase board so students can followexplain the vocab terms on the sheet. To assess student understanding, play a quick game of Genetics Bingo.
Call out one definition of the genetics vocabulary words at a time. Provide the teacher and the class feedback on types of jobs involving animals they might know about. Suggest responsibilities of those jobs. Play Genetics Bingo. Cross out the correct genetic term on your bingo card, matching it up with the definition the teacher gives. Try to match four terms vertically, horizontally, or diagonally. Explain your selections based on what you crossed off your card.
Guided Practice Exploration : Tell students you are now going to practice crossing parental traits for a dog using a Punnett square. Give each student a Punnett square practice worksheet. Begin by telling them we need to know which traits the mother of the dog has and which traits the father of the dog has. For this example, the big B will represent black hair and the little b will represent brown hair. Roll the first pair to determine the hair color of the mother.A kennel owner has a male dog that she wants to use for breeding purposes if possible.
The dog can hear, so the owner knows his genotype is either DD or Dd. This can be tested by breeding the dog to a deaf female dd. If you knew the genotypes of he offspring, you could tell what the male's genotype is. If any of the offspring are homozygous recessive ddthen you'd know for sure that the male is Dd. How could you tell?
Because if the dog's genotype was DD and you bred it to the same female it would be:. Another way, although a little more less conventional, is that an animal with a recessive gene and a dominant gene tends not to carry that trait as well as an animal with a DD.
For example, maybe the dog is not so adept at hearing. Two hearing dogs could produce deaf offspring if each of the dogs carry the recessive "d. Which would be:. Pam M. Draw the Punnett squares to illustrate these two possible crosses. How could you tell the genotype of this male dog? Also, using Punnett square sshow how two hearing dogs could produce deaf offspring.
Answer Save. Note: Only the female dog, carries the recessive allele. Good Luck. What do you think of the answers? You can sign in to give your opinion on the answer.