What is an allele? And how is a dominant trait is identified for example between tall and dwarf the dominant trait is tallness thats ok but how the dominant trait is identified please answer this briefly
What is an allele? And how is a dominant trait is identified for example between tall and dwarf the dominant trait is tallness thats ok but how the dominant trait is identified please answer this briefly
an allele is a variant form of a gene. Explained in greater detail, each gene resides at a specific locus (location on a chromosome) in two copies, one copy of the gene inherited from each parent. The copies, however, are not necessarily the same. When the copies of a gene differ from each other, they are known as alleles. A given gene may have multiple different alleles, though only two alleles are present at the gene’s locus in any individual.
A dominant trait is an inherited characteristic that appears in an offspring if it is contributed from a parent through a dominant allele. Traits, also known as phenotypes, may include features such as eye color, hair color, immunity or susceptibility to certain diseases and facial features such as dimples and freckles.
In sexually reproducing species, each individual has two pairs of chromosomes; humans have 23 pairs of chromosomes, and so 46 chromosomes in total. The chromosomes contain thousands of genes which code for the proteins that express and control all of the biochemical and physical features of an organism; this set of genes is an organism’s genotype.
Within each chromosome, there are two copies of each gene. Each chromosome carries the same gene in the same position (called a locus) so that they are paired. However, each locus may have two different versions of each gene: one received from the mother and one from the father. Each of the alternative versions of a gene is called an allele. Alleles come in two different forms: recessive(denoted as a small letter, e.g., a) and dominant (denoted as a capital letter, e.g., A).
If an individual carries the same two alleles for a gene, they are homozygous for that gene (aa or AA); this is the case whether the alleles are recessive or dominant. If the two alleles are different, the individual is heterozygous for the gene (Aa).
Assuming Mendelian Genetics, which is a simplified explanatory tool:
- A recessive trait will only be expressed if the offspring has two copies of the recessive allele that codes for the trait (recessive homozygous, aa).
- 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).
A dominant trait is an inherited characteristic that appears in an offspring if it is contributed from a parent through a dominant allele. Traits, also known as phenotypes, may include features such as eye color, hair color, immunity or susceptibility to certain diseases and facial features such as dimples and freckles.
In sexually reproducing species, each individual has two pairs of chromosomes; humans have 23 pairs of chromosomes, and so 46 chromosomes in total. The chromosomes contain thousands of genes which code for the proteins that express and control all of the biochemical and physical features of an organism; this set of genes is an organism’s genotype.
Within each chromosome, there are two copies of each gene. Each chromosome carries the same gene in the same position (called a locus) so that they are paired. However, each locus may have two different versions of each gene: one received from the mother and one from the father. Each of the alternative versions of a gene is called an allele. Alleles come in two different forms: recessive(denoted as a small letter, e.g., a) and dominant (denoted as a capital letter, e.g., A).
If an individual carries the same two alleles for a gene, they are homozygous for that gene (aa or AA); this is the case whether the alleles are recessive or dominant. If the two alleles are different, the individual is heterozygous for the gene (Aa).
Assuming Mendelian Genetics, which is a simplified explanatory tool:
- A recessive trait will only be expressed if the offspring has two copies of the recessive allele that codes for the trait (recessive homozygous, aa).
- 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).
