Frequent question: What is always a difference between alleles?

A gene is a portion of DNA that determines a certain trait. An allele is a specific form of a gene. Genes are responsible for the expression of traits. Alleles are responsible for the variations in which a given trait can be expressed.

What is it called when the alleles are different?

If the alleles are different, the individual is heterozygous. Though the term allele was originally used to describe variation among genes, it now also refers to variation among non-coding DNA sequences.

What causes different alleles?

Genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism’s offspring).

What is the best definition of allele?

Allele, also called allelomorph, any one of two or more genes that may occur alternatively at a given site (locus) on a chromosome. Alleles may occur in pairs, or there may be multiple alleles affecting the expression (phenotype) of a particular trait.

What is gene example?

For example, if both of your parents have green eyes, you might inherit the trait for green eyes from them. Or if your mom has freckles, you might have freckles too because you inherited the trait for freckles. Genes aren’t just found in humans — all animals and plants have genes, too.

Is a gene or chromosome bigger?

From smallest to largest: nucleotide, gene, chromosome, genome. … A gene is therefore composed of many pairs of nucleotides. A chromosome is a long strand of DNA which is coiled up with various proteins. A chromosome contains many genes.

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