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Is it possible for 2 homozygous recessive individuals to have a homozygous dominant child?
Wiki User
∙ 13y ago
No, homozygous recessive indivuals MUST have two of the reccessive gene (bb), the possible combinations are bb,bb,bb,bb thus only a recessive trait is possible
Wiki User
∙ 13y ago
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What is the probability that a recessive trait will appear?
It depends on the genotype of the parents, but assuming there is an equal chance of being dominant homozygous, recessive homozygous or heterozgous and there are only two possible genes, there is a 1 in 4 chance that the recessive trait will appear.
Where did the ratio 9331 come from include what each of these four numbers mean?
The 9/3/3/1 ration is the ratio of phenotypes that are the result of a dihybrid cross. Consider two genes, A and B, that reside on different chromosomes (so that they independently assort). Assume each gene has two alleles. For A, A is dominant and a is recessive, while for the B gene, B is dominant and b is recessive. Now consider a cross between two individuals that are heterozygous for both genes (this is called a dihybrid cross): AaBb X AaBb There are only 4 possible gametes that each individual can produce (in equal proportion): AB Ab aB ab So if we cross the two we get 16 combinations. This will result in 9 possible genotypes: AABB AABb AAbb AaBB AaBb Aabb aaBB aaBb aabb However, there are only 4 possible phenotypes (with proportion in parentheses): Dominant A and B (9/16) (AABB, AABb, AaBB, AaBb) Dominant A, Recessive B (3/16) (AAbb, Aabb) Recessive A, Dominant B (3/16) (aaBB, aaBb) Recessive A, Recessive B (1/16) (aabb)
A homozygous dominant black bear is mated with a recessive brown bear what phenotype will probably result in the offspring of the two bears?
Phenotype: Black Bear x Brown Bear Genotype: BB x bb Possible gametes: B B b b Possible B B crosses: b Bb Bb b Bb Bb Phenotype of offspring: Only Black bears
What is a pun net square?
Wikipedia says:The Punnett square is a diagram that is used to predict an outcome of a particular cross or breeding experiment. It is named after Reginald C. Punnett, who devised the approach. The diagram is used by biologists to determine the probability of an offspring having a particular genotype. The Punnett square is a tabular summary of possible combinations of maternal alleles with paternal alleles.[1] These tables can be used to examine the genotypic outcome probabilities of the offspring of a single trait (allele), or when crossing multiple traits from the parents. The Punnett Square is a visual representation of Mendelian inheritance. It is important to understand the terms "heterozygous", "homozygous", "double heterozygote" (or homozygote), "dominant allele" and "recessive allele" when using the Punnett square method. For multiple traits, using the "forked-line method" is typically much easier than the Punnett square. Phenotypes may be predicted with at least better-than-chance accuracy using a Punnett square, but the phenotype that may appear in the presence of a given genotype can in some instances be influenced by many other factors, as when polygenic inheritance and/or epigenetics are at work.
Can you complete the following Punnett Squares Thorny spine (T) is dominant to smooth spine (t) and pink spots (P) is dominant to blue spots (p) in brain eating slugs. There are four squares.?
On the left side of the square put the T as the first row, t as the second row. On the top put P as the first column and p as the second column. In the squares the first square is TP and next one is Tp. Lower left is tP and lower right is tp. This means the possible outcomes are Thorny pink, thorny blue, smooth pink and smooth blue. This is from parents that are heterogeneous. If parents were both homogeneous dominant the rows and columns would both have capital letters and only capital letters inside the square. What the Punnet square is trying to do is show all the possible combinations with two choices.
What are the three different combinations of alleles?
If the gene for a trait has two alleles, one dominant (D) and one recessive (d) there are three possible combinations in the genotype: DD (homozygous dominant) Dd (heterozygous) dd (homozygous recessive)
What gene is masked if it is paired with a dominant gene?
The different forms of a gene are called alleles. In Mendelian genetics, a gene has a dominant allele and a recessive allele. The dominant allele masks the recessive allele if present. So there are two possible dominant genotypes: homozygous dominant, in which both dominant alleles are present; and heterozygous, in which one allele is dominant and the other allele is recessive. The only way to express a recessive trait is to have the homozygous recessive genotype.
What is the probability that a recessive trait will appear?
It depends on the genotype of the parents, but assuming there is an equal chance of being dominant homozygous, recessive homozygous or heterozgous and there are only two possible genes, there is a 1 in 4 chance that the recessive trait will appear.
What is a genotype and 3 possible genotypes?
Homozygous dominant (Ex:AA) Heterozygous (Ex:Aa) Homozygous recessive (Ex:aa)
When an individual have two identical alleles for the same trait it is called?
Having two similar alleles for a trait is called being homozygous. It is possible to be homozygous for a dominant or recessive trait.
What is phenotype of Rr?
It is Dominant. R is the dominant and r is the recessive. The dominate trait shadows the recessive trait. It is Dominant. R is the dominant and r is the recessive. The dominate trait shadows the recessive trait. Is dominant. dominant can be RR or Rr. but when its recessive its rr.
How did Mendel know the the tall pea plants in the first generation had a hidden factor for shortness?
By "test cross" you can know whether it homozygous dominant or heterozygous dominant...in homozygous both alleles code for the dominant trait, in heterozygous one allele is recessive (what you called a "hidden factor"). To perform the test cross, cross a homozygous recessive with the first generation. Lets suppose tall pea tree in the first generation is hetrozygous dominant (Xx) and has alleles X (dominant) and x (recessive). When we cross it with homozygous recessive (xx) X x x :Xx xx x :Xx xx we get half offspring showing dominant trait (Xx) and half showing recessive (xx). If the first generation was homozygous (which is not possible) the result would be X X x: Xx Xx x: Xx Xx all the offspring showing dominant trait and it doesn't really happen when we cross the first generation with homozygous recessive. It means that the genotype of first generation is heterozygous (has a hidden factor or a recessive allele x). Note:You must know what the recessive and dominant allele means...In presence of a dominant allele, recessice character is not expressed but it is present is heterozygous. If both alleles are recessive (homozygous recessive) then the recessive trait is expressed. If both the alleles are dominant (homozygous dominant) obviusly the dominant trait is showed by the individual.
What is an example of two heterozygous parents?
The possible genotypes of parents who are heterozygous would be found using a punnet square. The outcome would be 50 percent heterozygous dominant, 25 percent homozygous dominant, and 25 percent homozygous recessive.
Predict what genotype the children will have if one parent is homozygous recessive for earlobes and homozygous dominant for hairline (eeWW) and the other parent is homozygous dominant for unattached earlobes and homozygous recessive for hairline (EEww )?
The only possible outcome is EeWw, which will express the dominant genes but carry the recessive ones. They get one chromosome from each parent, but since the parents all have matching chromsomes in this case then it doesn't matter which one they get. Since one parent has EE, E is the only one that can be passed on. Since the other has ee, they can only pass on e. Therefore, the child can only possible have Ee, as they get one from each parent.
What are the possible offspring outcome if parent one Tt crosses with parent to tt?
A heterozygous cross.Tt X TtOne homozygous dominant--TTTwo heterozygous dominant---TtOne homozygous recessive--ttAll on a statistical average outcome.
What are the possible genotypes for dwarfism?
There are many types of dwarfism. Acondroplastic dwarfism is a dominant trait. Living individuals are heterozygous for the trait as a homozygous dominant individuals have substantial skeletal anomalies that result in death in infancy.
How do geneticists normally tell whether an organism exhibiting a dominant phenotype is homozygous or heterozygous?
They perform a test cross. A test cross takes the unknown genotype and crosses it with a known homozygous recessive. If the F1 generation is all dominant, then they know the organism was a homozygous recessive. If recessive offspring appear, then the organism was a heterozygote. As an example, consider a gene with two alleles, A and a, with Adominant. Now consider the test cross. The unknown genotype can only be one of two possibilities: AA (homozgous dominant) Aa (heterozygous) In a test cross,the unknown genotype is crossed with a known homozygous recessive. Since there are only two possible unknown genotypes, there can be only two possible results. First, consider the case of the unknown genotype being a homozygous dominant. The cross looks like this: AA X aa Remember that a homozygote for an allele can only produce one kind of gamete. In this case the homozygous dominant can only produce gametes with the allele A in them, while the homozygous recessive can only produce gametes with the recessive allele a in them. This means the F1 offspring can only be ONE genotype; Aa. Therefore, all of the offspring would have the dominant phenotype. Now consider the other possible cross, where the unknown genotype is heterozygous: AaX aa Remember that a heterozygote can produce two types of gametes. In this case, the unknown would produce gametes with the dominant allele A or the recessive allele a. The homozygous recessive would still only produce one kind gamete, with the recessive a allele. Therefore, we expect to see only two genotypes in the F1, Aa and aa, in equal proportions. In either case, only one test cross is needed to tell one immediately the nature of the unknown genotype. If all of the F1 are of the dominant phenotype, then the unknown genotype must be homozygous dominant; if a mixture of phenotypes appears in equal proportion, then the unknown genotype must be a heterozygote.
