Genes
Recessive
Mendel
Dominant
Alleles
Genotype
Homozygous
Heterozygous
Phenotype
Genotype is the genetic code of an organism, that can be represented as, for example, XX Xx or xx. Genotypes are expressed as Phenotypes.
Example: The genotype for heterozygous brown eyes could be represented by the genotype 'Bb' (B= brown eyes, b= blue eyes)
Example: The allele for brown eyes and brown hair are dominant.
A dominant allele is always expressed if it is within the genotype. It can be found in heterozygous (Xx) and homozygous (XX) gene pairs.
Heterozygous phenotypes have a genotype with different alleles.
Example: Heterozygous brown have the genotype Bb, because those two alleles are different.
Example: A flower can have a dominant allele for pink petals, while another flower can have a recessive allele for yellow petals.
An allele is a variant form of a gene
Example: A person's genotype is Bb (heterozygous brown eyes). Because brown eyes are a dominant trait, that person's phenotype will be brown eyes.
Phenotype is the physical you have based on your genotype. Sometimes recessive alleles in your genotype aren't represented in your phenotypes as they are typically hidden traits.
Example: A well-known recessive trait is blue eyes and blonde hair.
A recessive allele won't be expressed in your phenotype unless your genotype is, for example, xx. A recessive allele is typically hidden behind a dominant allele.
Examples: Homozygous genotypes are "XX" and "xx". A homozygous phenotype would be blue eyes.
Homozygous genotypes are ones that have the same alleles.
Gregor Mendel was an Austrian monk, who discovered the basics of heredity.
Example: A way Mendel studied heredity was by observing pea plants.