Is it possible to determine the genotype of an individual expressing a dominant phenotype?

There is no way to tell these genotypes apart visually, but there is a well-established experimental technique to determine the fly’s genetic makeup. Specifically, to detect the underlying genotype of an organism with a dominant phenotype, one must do a type of breeding analysis called a test cross.

How do you determine dominant phenotype?

Use the Hardy-Weinberg equilibrium.

1. Alleles: p+q=1.
2. p=frequency of the dominant allele.
3. p2=frequency of homozygous dominant genotype.
4. In your scenario, the dominant phenotype has a frequency of 0.19 .
5. This is misleading, since both the p2 and 2pq terms represent the dominant phenotype.
6. If q2=0.81 , we can determine q .

How do you tell if a genotype is dominant or recessive?

A dominant allele is denoted by a capital letter (A versus a). Since each parent provides one allele, the possible combinations are: AA, Aa, and aa. Offspring whose genotype is either AA or Aa will have the dominant trait expressed phenotypically, while aa individuals express the recessive trait.

How do you determine a person’s genotype?

An obvious way to figure out you genotype is to have a genetic test done. Companies like 23andMe can do this pretty inexpensively nowadays. For this to work, though, scientists have to have figured out the genetic difference that leads to a trait.

How do you determine the genotype of an individual?

A testcross can be used to determine the organism’s genotype. In a testcross, the individual with the unknown genotype is crossed with a homozygous recessive individual (Figure below). Consider the following example: Suppose you have a purple and white flower and purple color (P) is dominant to white (p).

How do you find the genotype of a heterozygous?

To find q, simply take the square root of 0.09 to get 0.3. Since p = 1 – 0.3, then p must equal 0.7. 2pq = 2 (0.7 x 0.3) = 0.42 = 42\% of the population are heterozygotes (carriers).

Which of the following is a heterozygous dominant genotype?

An organism with two dominant alleles for a trait is said to have a homozygous dominant genotype. Using the eye color example, this genotype is written BB. An organism with one dominant allele and one recessive allele is said to have a heterozygous genotype. In our example, this genotype is written Bb.

When the genotype consists of a dominant and a recessive allele?

An organism with one dominant allele and one recessive allele is said to have a heterozygous genotype. In our example, this genotype is written Bb. Finally, the genotype of an organism with two recessive alleles is called homozygous recessive.

How do you determine the genotype of a parent?

To construct a Punnett square, the genotypes of both parents must be known. One parent’s alleles are listed across the top of the table, and the other parent’s alleles are listed down the left hand side. The resulting offspring genotypes are produced at the intersection of the parent’s alleles.

How do you determine the genotype of an individual with dominant phenotype?

To determine the genotype of an individual that shows the dominant phenotype you would cross that individual with one that is? To determine the genotype of an individual that shows the dominant phenotype you would cross that individual with one that is homozygous recessive.

How do you know if a phenotype is heterozygous or recessive?

If both dominant alleles are present in a genotype (homozygous dominant) then the phenotype is “A” phenotype. If one dominant allele and one recessive allele are present (heterozygous dominant) then the phenotype is “A”. Finally, if both recessive alleles “a” are present (homozygous recessive) then the phenotype is “a”.

What is the genotype and phenotype of RR and RR?

Capitals are generally used to denote the dominant trait. In homozygous dominant individuals, genotype RR, the phenotype will be R. In homozygous recessive individuals, genotype rr, the phenotype will be r and in heterozygous individuals, genotype Rr, the phenotype will be R.

How does seselection act on phenotypes?

Selection acts on phenotypes because differential reproduction and survivorship depend on phenotype. If the phenotype affecting reproduction or survivorship is genetically based, then selection can winnow out genotypes indirectly by winnowing out phenotypes. Home Science Math and Arithmetic History