What does cloning mean and what is considered a human clone? What types of human cloning are there?
The act of producing a
genetically identical copy of a biological material, whether that is tissues,
cells, or organisms, can be described by the term ‘cloning’ ("Cloning").
The idea of human cloning first came into play when a sheep named Dolly was
successfully cloned ("Cloning Fact Sheet"). The government of Canada
defines a human clone as an embryo that contains chromosomes from a single
(dead or alive) human which was gained through the manipulation of reproductive
material ("Human Cloning"). However, human cloning does not
necessarily mean reproductive cloning. Another type of human cloning is
therapeutic cloning ("Cloning Fact Sheet").
Reproductive Cloning
In sexual reproduction, half the genes that the baby
receives are from the mother and the other half is from the father ("Human
Cloning and Genetic Modification"). However, reproductive cloning is
asexual reproduction. This means that all the genes that the baby receives are
from a single parent ("Human Cloning and Genetic Modification"). As a
result, the child will have the exact same genetic code as the gene donor and
become a clone of them ("Human Cloning and Genetic Modification"). The genetic code contains exactly 64 nucleotides that are in sequence of threes. These triplets are called codons; they code for amino acids (Giuseppe 240). In turn, chains of amino acids form proteins. Proteins are molecules that determine a person’s appearance and physical traits and direct cellular activity (Giuseppe 234).
The process of reproductive cloning has many steps. First a body cell, also known as a somatic cell, is removed from the person that is being cloned ("Cloning"). Then the DNA from the somatic cell has to be put in an egg cell that has already had its nucleus (which contains the DNA) removed ("Cloning"). DNA stands for deoxyribonucleic acid. It is double stranded and in the shape of a helix and is the source of an organism’s hereditary information and is mainly located in the nucleus (Giuseppe 206). Also, DNA is a polymer that is made up of nucleotides. Each nucleotide contains a nitrogenous base, a phosphate, and a deoxyribose sugar; adenine, guanine, cytosine, and thymine are the four nitrogenous bases that are found in DNA (Giuseppe 210). In reproductive cloning, DNA is extracted from the parent and inserted into an egg cell in order to pass on the hereditary information ("Cloning"). There are two ways that the DNA from the somatic cell can be put into the empty egg cell. One method is to use electricity to combine the somatic cell and egg cell into one ("Cloning"). The other method is to extract the DNA from the somatic cell and then have it be put in the egg cell ("Cloning"). Following that, the egg is put in a test-tube to grow into a young embryo. The embryo is then transferred into a surrogate mother ("Cloning"). When the baby is born, he/she will now be genetically identical to the person who donated the somatic cell ("Cloning"). |
Therapeutic Cloning
To understand therapeutic cloning, one must first understand stem cells. Stem cells are unspecialized cells that have the potential to become various cell types ("Stem Cell Basics"). Two features of the stem cell help separate it from other cells. One is that they can continually be renewed through cell division to repair other cells ("Stem Cell Basics"). The other feature is that they can be induced to become a specific cell that has a specialized role in the body; examples include brain and muscle cells ("Stem Cell Basics").
In therapeutic cloning, the purpose is to create embryonic stem cells that are compatible with the patient that needs it ("Cloning"). This can be done by creating a cloned embryo of the patient and then extracting the stem cells from the embryo ("Cloning"). Scientists can then induce these cells to become specialized for specific functions and grow into the tissue or organ that is wanted ("Human Cloning and Genetic Modification"). By using therapeutic cloning, stem cells from an embryonic clone of the patient can be injected to patient and will not be rejected as the DNA of the stem cells will match the patient’s DNA ("An Overview of Stem Cell Research"). If foreign embryonic stem cells were used, the patient could feel side effects and the cells may be rejected by the patient’s body ("An Overview of Stem Cell Research"). |