Answer: Heredity is the transfer of characters (traits) from parents to offspring through genes.
Mechanism:
- Characters are controlled by genes, which are segments of DNA located on chromosomes. DNA carries information as a sequence of nucleotides.
- The genetic information in DNA is copied into mRNA (transcription), and mRNA is translated into specific proteins. These proteins produce the characters.
- Before cell division DNA replicates, and in sexual reproduction each parent passes one set of chromosomes to the offspring through gametes.
- If the nucleotide sequence of a gene changes (mutation), or new combinations of genes arise during gamete formation and fertilisation, the proteins and so the characters change. Such changes in germ cells are passed to the next generation, producing hereditary variation.