Final answer:
The fundamental unit of heredity is the gene, which is a sequence of DNA on chromosomes that carries genetic information and can be replicated, expressed, or mutated. Gregor Mendel's work laid the foundation for our understanding of genetics and heredity. Alleles are variations of genes that contribute to the organism's phenotype, and the complete set of genes is called the genome.
Step-by-step explanation:
The fundamental unit of heredity, which carries information from one generation to the next, is the gene. Genes are the basic functional units of heredity that are capable of being replicated, expressed, or mutated. They are sequences of DNA located on chromosomes within the cell nucleus. The genetic code is a set of rules by which information encoded within genetic material (DNA or RNA sequences) is translated into proteins by living cells. The physical expression of these genes, upon being transcribed and translated, leads to the individual's phenotype, which is the composite of the organism's observable characteristics or traits.
The work of Gregor Mendel contributed significantly to our understanding of heredity. He discovered that traits are inherited according to specific laws, now known as Mendelian genetics. While not all traits follow these patterns strictly, Mendel's principles serve as a foundation for classical genetics.
Moreover, genes can exist in different forms called alleles, which are variations of the genetic sequence that may result in different traits being expressed. The complete set of genes within an organism is referred to as its genome, and during reproduction, genes are passed from parents to offspring, ensuring the continuity of genetic information across generations.