2.2 DNA as carrier

DNA as carrier from genetic information passed to next generation

As a breeder you want to transfer the best genetic material you can get from the present to the next generation of animals. This genetic material is stored in the chromosomes in the nucleus of all cells of the animals that may be selected as parents for the next generation. This transfer process takes place with the transfer of chromosomes  containing the genes via the creation of sperm cells and oocytes in the gonads. The combination of a sperm cell and an oocyte into a zygote is the starting point of a new animal with a unique genetic composition. In the transfer of chromosomes from parents to offspring the meiosis plays an important role. It causes that the transfer is determined to some extend by laws, recognized by Mendel (see chapter 1) and to some extend by random processes. The laws connect genetically relatives, e.g. parents and their offspring: the parents each share for 50% the same chromosomes, the same DNA and thus the same genetic value with their offspring. Therefore phenotypic traits of parents, can be found in the phenotypic traits of their offspring, based on the genes they got from their parents. In conclusion: offspring and parents and more in general related animals share a part of their DNA; they have a genetic relationship.

Chromosomes as units of DNA

Body cells of mammals and birds have a nucleus where pairs of chromosomes (units of DNA) are found. Each species has a specific number of chromosomes as is illustrated in the table below:

Number of chromosome pairs for different species