Similarities Between Allele and Locus 5. An allele is an alternative form of a gene. In simple words, alleles refer to different versions of a gene. There are often two alleles of one gene. But it can vary. More than two alleles may be present in genes. However, they located at the same location as the homologous chromosomes which calls locus.
The DNA sequence or the nucleotide sequence differs between alleles of the same gene due to mutations. This leads to different observable phenotypic traits as well as genetic disorders.
Humans often have two alleles at each genetic locus since they are diploid and acquire one homologous chromosome from each parent during fertilization. According to the Mendelian genetics, alleles can be either dominant allele or recessive allele depending on their associated traits.
A dominant allele can express its phenotypic trait even when the one allele is present. But to express the recessive phenotypic trait, both alleles should be recessive homozygous recessive at the locus. The dominant allele is the one which actually codes for the protein, while the recessive one does effectively nothing.
This is why certain characteristics may skip a generation. If you have one parent with blue eyes and one with brown, you will receive both alleles, so have the potential for either colour. However, you will only show one: the dominant variant. If you then have a child, you could pass on either of those alleles, regardless of which one is active, and so your child could end up with blue eyes from the blue eyes buried inside you. Loci from Latin locus meaning place are just positions on the DNA.
Locus is to some extent interchangeable with gene, though locus is less specific and doesn't imply that the location codes for an entire gene.
Different versions of the same gene are called alleles. Genes can have two or more possible alleles. Individual humans have two alleles, or versions, of every gene. Because humans have two gene variants for each gene, we are known as diploid organisms.
The greater the number of potential alleles, the more diversity in a given heritable trait. An incredible number of genes and gene forms underly human genetic diversity, and they are the reason why no two people are exactly alike. In a simplified model, we will assume that there is only one gene that encodes for eye color although there are multiple genes involved in most physical traits.
Blue, green, brown, and hazel eyes are each encoded by unique alleles of said gene. When humans procreate, the child receives 23 chromosomes long strands of DNA from each parent. Each matching chromosome pair contains the same set of genes, with unique genes located at certain spots known as the gene locus. This inheritance means that individuals have two gene copies for a given trait, one inherited from their mother and the other from their father.
These are known as maternal alleles and paternal alleles. Each pair of alleles represents the genotype of a specific gene. Genotypes are described as homozygous if there are two identical alleles at a particular locus and as heterozygous if the two alleles differ.
Alleles contribute to the organism's phenotype, which is the outward appearance of the organism. Some alleles are dominant or recessive.
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