* Chromosomes: These are thread-like structures found in the nucleus of every cell. They are made up of DNA, which contains the genetic blueprint of an organism.
* Genes: Genes are segments of DNA that carry the instructions for building and maintaining an organism. Each gene holds the code for a specific protein, or a set of proteins, that determines a particular trait.
* Alleles: Genes come in different versions called alleles. These versions can influence the expression of a trait. For example, a gene for eye color might have alleles for brown, blue, or green eyes.
* Genotype: This refers to the combination of alleles an organism inherits from its parents.
* Phenotype: This refers to the observable characteristics of an organism, which are influenced by its genotype.
Here's a simplified example:
* Gene: Eye color gene
* Alleles: Brown eye allele (B), Blue eye allele (b)
* Genotypes: BB (brown eyes), Bb (brown eyes), bb (blue eyes)
* Phenotypes: Brown eyes, blue eyes
Therefore, the specific characteristics of an organism are determined by:
* The specific genes present on its chromosomes: Which genes an organism inherits dictates the proteins it can produce.
* The combination of alleles for each gene: The specific versions of the genes will influence how the traits are expressed.
It's important to note that the environment also plays a role in shaping an organism's characteristics. For example, diet and exercise can influence body size, even though the genes for height are present.
