1. Genetic Origin:
A cloned animal is genetically identical to the donor cell providing its nucleus. This means the cloned animal carries the exact same genetic information as the original donor. In contrast, sexually produced animals inherit genetic material from both parents through the fusion of gametes (egg and sperm), leading to genetic diversity and mixing of traits.
2. Mitochondrial DNA (mtDNA):
During SCNT, the recipient's egg's cytoplasm, including its mitochondria, is usually used. This results in the cloned animal having the mitochondrial DNA of the egg donor and not the donor of the somatic cell nucleus. However, in some cases, methods have been developed to preserve the somatic cell's mitochondrial DNA, which means the cloned animal may have mtDNA from both the egg donor and the donor of the somatic cell nucleus. Sexually reproduced animals, on the other hand, inherit mtDNA exclusively from the mother, as it is found only in the egg.
3. Epigenetic Modifications:
Epigenetic modifications are chemical changes to the DNA that affect gene expression without altering the DNA sequence itself. SCNT can lead to changes in epigenetic patterns when the somatic cell nucleus is reprogrammed to behave like an embryonic nucleus. This can result in differences in gene expression and, potentially, phenotypic variations between cloned animals and their genetic counterparts produced by sexual reproduction. Epigenetic modifications can also be influenced by factors such as the age and type of the donor cell, as well as the recipient egg's environment.
4. Developmental Abnormalities:
In some cases, cloned animals may experience developmental abnormalities or health issues due to reprogramming challenges or disruptions during the cloning process. These abnormalities can range from minor physical defects to major health complications, including increased susceptibility to certain diseases or reduced fertility.
It's important to note that the technology and techniques used in cloning are constantly advancing, and researchers continue to optimize the process to minimize these differences and ensure the well-being and health of cloned animals.