The brown allele is recessive.
Think: Blue = B, and brown = b
Your friend is Bb, or heterozygous for the gene. In heterozygotes, the expressed phenotype is the dominant gene, which in this case, apparently, is blue. Thus, because your friend does not have brown eyes, the brown allele must be recessive.
An allele that is masked by the dominant allele is called a recessive allele. When an individual has one dominant allele and one recessive allele, only the trait determined by the dominant allele will be expressed. The recessive allele will only be expressed if an individual has two copies of it (homozygous recessive).
Recessive allele disorders are just as they sound - they are disorders that are a result of a prevalent recessive allele in one's genetic makeup. A recessive allele disorder will rarely occur since it is dependent on the crossing of two heterozygous parent cells, but it can lead to interesting consequences. An example of a recessive allele disorder is hemophilia - the body's inability to clot blood - and it has affected much of the European royalty in history, such as Queen Victoria of Great Britain.
A dominant allele is a version of a gene that is expressed when present, masking the effects of a recessive allele when both are present in an individual. It is represented by a capital letter in genetics notation, such as "A" for a dominant allele and "a" for a recessive allele.
a dominant allele is basically the one stronger, more powerful. unlike the recessive allele, i.e if two people wanted to calculate the probability of them having a baby with brown eyes, theyd have to look at their alleles, if the father had brown eyes, XX (to show how brown eyes are stronger) and the mother had hazel eyes (xx) their chid is going to have (Xx) which in this case, the child will have brown eys, because X is more dominant(strong) than x (recessive)
Examples of dominant genes include brown eyes and attached earlobes, where the dominant allele will be expressed over its recessive counterpart. Recessive genes include blue eyes and detached earlobes, which will only be expressed when an individual has two copies of the recessive allele.
An allele that is masked by the dominant allele is called a recessive allele. When an individual has one dominant allele and one recessive allele, only the trait determined by the dominant allele will be expressed. The recessive allele will only be expressed if an individual has two copies of it (homozygous recessive).
Recessive allele disorders are just as they sound - they are disorders that are a result of a prevalent recessive allele in one's genetic makeup. A recessive allele disorder will rarely occur since it is dependent on the crossing of two heterozygous parent cells, but it can lead to interesting consequences. An example of a recessive allele disorder is hemophilia - the body's inability to clot blood - and it has affected much of the European royalty in history, such as Queen Victoria of Great Britain.
A dominant allele is a version of a gene that is expressed when present, masking the effects of a recessive allele when both are present in an individual. It is represented by a capital letter in genetics notation, such as "A" for a dominant allele and "a" for a recessive allele.
blue eyes blonde hair etc.. brown eyes and brown hair are dominant
dominant-appears in first generation recessive-seems to dissapear
A dominant allele is an allele where its phenotype will always be represented when the allele for that gene is present. A recessive allele can be masked by a dominant allele when a dominant and recessive allele are present for the same gene. A recessive allele will only present itself when two recessive alleles for a trait are present.
In this population, 20 out of 100 rabbits have white fur, indicating they are homozygous recessive (bb). The frequency of the recessive genotype (bb) is 0.20. Using the Hardy-Weinberg principle (p² + 2pq + q² = 1), we know q² = 0.20, so q (the frequency of the recessive allele) is the square root of 0.20, which is approximately 0.447. Thus, the allele frequency for the recessive allele is about 0.447.
a dominant allele is basically the one stronger, more powerful. unlike the recessive allele, i.e if two people wanted to calculate the probability of them having a baby with brown eyes, theyd have to look at their alleles, if the father had brown eyes, XX (to show how brown eyes are stronger) and the mother had hazel eyes (xx) their chid is going to have (Xx) which in this case, the child will have brown eys, because X is more dominant(strong) than x (recessive)
In diploid organisms (those with two copies of each gene carried on separate chromosomes), one of the copies of a given gene may differ from the other copy of the same gene on the twin chromosome. In some cases one version of the gene (the dominant allele) has the effect of 'masking' the activity of the other (the recessive allele); that is, the presence of the dominant allele negates the effect of the recessive allele on the organism's phenotype. There are many mechanisms which can cause this phenomena, and it depends on the particular genes involved, but a simple model is one where the recessive allele is a biochemically inactive version of the dominant allele. In this case the dominant allele would mask the effect of the recessive allele by providing an active version of the gene. The dominant phenotype would be the one which shows the downstream effects of this activity, and the recessive phenotype one which shows the downstream effects of a lack of activity. The dominant allele is said to 'mask' the recessive allele because only one copy is required to result in an elimination of the recessive phenotype, whereas all copies of the gene must be the recessive allele to result in the recessive phenotype.
Solid color in cats. Two brown tabby cats might produce a solid black kitten, if they both carry the recessive allele for solid color (which is called "non-agouti").
Examples of dominant genes include brown eyes and attached earlobes, where the dominant allele will be expressed over its recessive counterpart. Recessive genes include blue eyes and detached earlobes, which will only be expressed when an individual has two copies of the recessive allele.
In simple Mendelian genetics, there may be several alleles (variations) for a given trait. since organisms generally have two pairs of chromosomes, they have two alleles. A dominant allele is one that when it is present, always shows itself. A recessive allele only shows when there are two copies of the recessive allele. For example, suppose brown hair is dominant and black hair is recessive. If there are any copies of the brown hair allele, the person's hair will be brown. A person's hair will be black only if they have two copies of the black hair allele. In reality, genetics is much more complicated than simply dominant and recessive as many genes may influence one trait.