Twins: The Two Sets of Identical Twins
One of the most important things to understand identical twins are also known as monozygotic twins. They result from the fertilization of a single egg that splits in two. Identical twins share all of their genes and are always of the same sex. In contrast, fraternal, or dizygotic, twins result from the fertilization of two separate eggs during the same pregnancy. They share half of their genes, just like any other siblings. Fraternal twins can be of the same or different sexes.
The two sets of identical twins will not have identical children. If the two identical twins marry and have children then there resulting children will not be identical because the only way you can get identical is when a fertilized egg splits into two cells. Identical twins share the exact same genetic material, egg/sperm, and all (fraternal twins are conceived from a different egg/sperm). So in this case, the four “sets” of DNA are the same as only two sets. These twins are called monozygotic twins, which literally means they come from the same cell: ‘mono’ meaning one, and ‘zygotic’ meaning a fertilized cell. Since monozygotic twins developed from the same cell, they have identical DNA. Their children wouldn’t inherit traits from their parents because of a process called ‘genetic recombination: Genetic recombination occurs during a special type of cell division that forms egg or sperm cells, when the chromosomes swap their genes in a unique way, forming genetically unique eggs or sperm. In conclusion, the two identical twins who decide to have children will not be identical, they might be fraternal but not identical.
Genetic recombination would mix up the chromosomes, and all of your wife’s eggs would differ from each other. When one of the eggs from the woman comes into contact with one of the sperm from the man during fertilization it creates a very unique child. There are always scientific questions about this topic specifically like “Is there a possibility that the genes would recombine in the same way in an egg or sperm so that the identical twin pairs have identical children?.” The answer to this question is not really, according to Professor Rodney Scott, head of medical genetics at the University of Newcastle, there is “an infinite variety of genomes that you can come up with.” The likelihood that the genes will recombine identically is the same as that of parents having two children, at different times, which are identical, is a very small chance. Mitosis is a process where a single cell divides into two identical daughter cells and is also a process used to grow and then eventually replace worn-out cells. Meiosis is a process where a single cell divides twice to produce four cells containing half the original amount of genetic information and meiosis is responsible for making our sex cells or gametes. Mitosis and Meiosis both involve cell dividing to make new cells. This makes them both vital processes for the existence of living things that reproduce sexually. Alleles are one or two more versions of a gene. An individual inherits two alleles for each gene, one from each parent. If the two alleles are the same, the individual is homozygous for that gene. If the alleles are different, the individual is heterozygous. Though the term allele was originally used to describe variation among genes, it now also refers to variation among non-coding DNA sequences. Things to remember are that a zygote is the cell formed when two gametes fuse during fertilization. The DNA material from the two cells is combined in the resulting zygote. The cellular mechanisms present in the gametes also function in the zygote, but the newly fused DNA produces a different effect on the new cell. In single-celled organisms, the zygote becomes a fully functioning organism and can divide through mitosis to produce offspring. The organism can also produce gametes to reproduce sexually with other cells. At the same time, there there are more chances than not o them possibly being identical because identical twin pairs carry genes that mean they have a higher likelihood than non-twin couples of having children that are identical twins.
Punnett Squares are used in many ways and allow people to see what the possible genotypes of various offspring will be. They are really helpful in determining the possible genotypes of offspring and can be thought of as math multiplication tables. They can be used in every type of breeding, including single hybrid crosses, dihybrid crosses, trihybrid crosses, purebred crosses, and many others! Punnett Squares are one of the easiest ways to determine a specific trait someone will inherit from their parents is to use the Punnett Square. Then there are phenotypes which are traits essentially. In contrast, your phenotype is a description of your actual physical characteristics. This includes straightforward visible characteristics like your height and eye color, but also your overall health, your disease history, and even your behavior and general disposition. While all of this is true, it still doesn’t give an explanation that leads up to how identical twins come nearly the same. For some traits, two alleles can be co-dominant. That is to say, both are expressed in heterozygous individuals. An example of this is people who have an AB blood type for the ABO blood system. When they are tested, these individuals actually have the characteristics of both type A and type B blood. Their phenotype is not intermediate between the two. The traits of pod color and seed color are transmitted to the offspring independently of one another. Independent assortment is a basic principle of genetics developed by a monk named Gregor Mendel in the 1860s. Mendel formulated this principle after discovering another principle now known as Mendel's law of segregation. For any particular trait, the pair of alleles of each parent separately and only one allele passes from each parent on to an offspring. Which allele in a parent's pair of alleles is inherited is a matter of chance. We now know that this segregation of alleles occurs during the process of sex cell formation (i.e., meiosis) apparent blending can occur in the phenotype when there is incomplete dominance resulting in an intermediate expression of a trait in heterozygous individuals. For instance, in primroses, snapdragons, and four-o'clock, red or white flowers are homozygous while pink ones are heterozygous. The pink flowers result because the single 'red' allele is unable to code for the production of enough red pigment to make the petals dark red. Karyotypes are a picture of a person’s chromosomes. In order to get this picture, the chromosomes are isolated, stained, and examined under the microscope. Most often, this is done using the chromosomes in the white blood cells. A picture of the chromosomes is taken through the microscope. Then, the picture of the chromosomes is cut up and rearranged by the chromosome’s size. The chromosomes are lined up from largest to smallest. A trained cytogeneticist can look for missing or extra pieces of the chromosome.
