The genetic makeup of an organism, represented by the combination of alleles an individual possesses for a particular gene or set of genes.

Here's a breakdown:

* Genetic makeup: This refers to the specific sequence of DNA an organism inherits from its parents.

* Alleles: These are alternative forms of a gene. For example, the gene for eye color might have alleles for blue eyes or brown eyes.

* Combination of alleles: An individual inherits one allele for each gene from each parent, resulting in a specific combination of alleles for that gene.

Example:

If we consider a gene for flower color with alleles for red (R) and white (r), an individual could have the following genotypes:

* RR: homozygous dominant (red flowers)

* rr: homozygous recessive (white flowers)

* Rr: heterozygous (red flowers)

Key points:

* Genotype is the underlying genetic code, whereas phenotype is the observable physical characteristic (e.g., flower color).

* Genotype determines phenotype, but the environment can also influence how a genotype is expressed.

* Genotype is an important concept in genetics, as it helps to understand how traits are inherited and expressed.