What type of allele will be expressed if both dominant and recessive alleles are present for a given trait?

A dominant phenotype will be expressed when at least one allele of its associated type is present, whereas a recessive phenotype will only be expressed when both alleles are of its associated type. However, there are exceptions to the way heterozygotes express themselves in the phenotype.

When both dominant and recessive alleles are present?

If both of the alleles you inherited from your parents are the same, the genotype is homozygous. However, if you have one dominant and one recessive allele, the genotype is heterozygous.

What trait dominant or recessive will be expressed if an organism has one dominant allele and one recessive allele?

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.

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What is it called when two genes are recessive or dominant?


= Codominance is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent. If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked.

Can a recessive allele be expressed?

When a trait is recessive, an individual must have two copies of a recessive allele to express the trait. Recessive alleles are denoted by a lowercase letter (a versus A). … Let (S) represent the dominant allele, and (s) represent the recessive allele. Only (ss) individuals will express a smooth chin.

Why are dominant alleles expressed over recessive?

The simplest situation of dominant and recessive alleles is if one allele makes a broken protein. When this happens, the working protein is usually dominant. The broken protein doesn’t do anything, so the working protein wins out. … If both copies of your MC1R gene code for broken proteins, then you’ll have red hair.

What happens when you have one dominant and one recessive allele?

When an organism is heterozygous at a specific locus and carries one dominant and one recessive allele, the organism will express the dominant phenotype. Alleles can also refer to minor DNA sequence variations between alleles that do not necessarily influence the gene’s phenotype.

Which allele is dominant?

If the alleles of a gene are different, one allele will be expressed; it is the dominant gene. The effect of the other allele, called recessive, is masked.

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Why is a dominant allele called dominant?

A dominant allele is called dominant because it masks the recessive trait and is expressed in the phenotype of a heterozygous organism. Only a single allele is sufficient to express the trait.

What do we call to an individual with one dominant and one recessive allele?

For a recessive allele to produce a recessive phenotype, the individual must have two copies, one from each parent. An individual with one dominant and one recessive allele for a gene will have the dominant phenotype.

What will be the phenotype and genotype of an organism when both genes are dominant?

Recessive alleles only express their phenotype if an organism carries two identical copies of the recessive allele, meaning it is homozygous for the recessive allele. This means that the genotype of an organism with a dominant phenotype may be either homozygous or heterozygous for the dominant allele.

When is a dominant trait expressed?

A dominant trait will always be expressed in the offspring if the dominant allele is present, even if there is only one copy of it (heterozygous or dominant homozygous, Aa or AA).

Are both dominant and recessive alleles transcribed?

Both dominant and recessive alleles are transcribed and translated. Even when they are in a heterozygous state (e.g., there is both a dominant and recessive allele present), they are both transcribed and translated. The proteins that are encoded by recessive alleles are nonfunctional.

How are dominant alleles shown?

Dominant alleles show their effect even if the individual only has one copy of the allele (also known as being heterozygous?). For example, the allele for brown eyes is dominant, therefore you only need one copy of the ‘brown eye’ allele to have brown eyes (although, with two copies you will still have brown eyes).

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