Alright buddy, this time we will discuss about Mendel’s Laws of Perversion, we will immediately enter into the discussion.
Mendel’s Laws of Deviance
Mendel’s law pseudo deviation is a form of cross that produces different ratios of individuals on the basis of the ratio according to Mendel’s law, although the principles of crossing still follow Mendel’s law. The difference in the ratio results occurs because there are several genes that influence each other in producing the phenotype (visible trait). The following are various types of pseudo-deviation of Mendell’s law.
Allele interaction is an event where the emergence of a phenotype (visible trait) which is influenced by interactions between dominant genes and interactions between recessive genes.
For example, in chickens, there are four types of wattles (comb), including (1) pea (pea or seed-shaped) with rrP genotype, (2) single with rrpp genotype, (3) rose (rose or tooth-shaped) with Rpp genotype, and (4) walnut (sumpel form) with RP- genotype.
If a cross between a rose with a rose and a pea breed is carried out, a new phenotype will be produced, namely a walnut with a walnut (sumpel). This new phenotype is generated due to the interaction of two pairs of dominant alleles. Look at the following crosses for more details.
If a cross between walnut-red chickens is carried out, the phenotype will be walnut, rose, pea, and single-winged chickens with a ratio of 9:3:3:1. Single-winged chickens occur due to the presence of two pairs of recessive alleles (less visible). For more details, see the table below.
Cryptometry is a condition where it seems as if the dominant gene is hidden if it stands alone and will only appear when it is together with other dominant genes, not alleles.
This event was discovered by Correns by crossing the red Linaria marocanna flower (Aabb), with the white Linaria maroccana flower (aaBB). The first offspring (F1) produced are purple flowers (AaBb) which are different from the colors of the flowers of the two parents (ie red and white). If the first offspring are crossed, the second offspring (F2) will be 9 purple: 3 red: 4 white. This can be understood by observing the following table.
The purple F1 offspring were obtained due to environmental changes. Linaria maroccana flowers will be red in an acidic environment due to the presence of anthocyanin pigments and an alkaline environment, this pigment will give a purple color. However, if there is no anthocyanin pigment in the plasma, either in an acidic or alkaline environment, then a white color is formed.
Polymery is a heterozygous cross of more than one different trait that stands alone, but affects the same part of an organism.
The polymerization event was introduced by Lars Frederik Nelson and Ehle. They conducted an experimental cross between red-seeded wheat and white-seeded wheat. Look at the following cross table.
Based on the cross table above, a cross between a red-seeded wheat and a white-seeded wheat resulted in a new phenotype (F1), namely the heterozygous offspring were pink in color when compared to the homozygous (red) parent. Therefore, red seeds are imperfectly dominant over white.
If the new phenotypes (F1) produced are crossed with each other, then the new phenotypes produced (F2 generation) are red-grained wheat and white-seeded wheat in a ratio of 3:1.
Epistasis-hypostasis is an event in which a dominant gene masks the expression of another dominant gene that is not its allele. One or a pair of masking genes is called epistasis while a pair of masked genes is called hypostasis. For example, a cross between black corn and yellow corn. Consider the following crossover.
P : HHkk x hhKK
(black) x (yellow)
From the results of these crosses, even though H and K are together and both are dominant. However, the trait that appears is black. In a sense, black acts as an epistasis (covering) against yellow. Yellow here is hypostatic (covered) by black.
Complementary is the interaction between dominant genes that are different, but complement each other to give rise to a phenotype (visible trait. For example, marriage between two people who are both deaf-mute. Consider the following table.
From the table, the first offspring (F1) from a marriage between two people who are both deaf-mute are normal. If the first offspring are crossed with each other, the resulting F2 generation or offspring is in accordance with the table above. Based on the table, the second offspring (F2) produced are normal and deaf-mute. The ratio of the F2 (second offspring) produced is normal: deaf mute is 9: 7.
To more easily understand the event of atavism, you try to remember again about the interaction of genes in the rooster’s wattle. When a chicken with rose and pea is crossed, it produces a walnut with a walnut. The wattle of the pea is said to disappear and a new trait emerges outside of its parent. Then, when another cross is carried out between chickens with walnut wattles, the offspring produced are chickens with four types of wattles, namely rose, pea, walnut, and single. In this event, wattle roses and peas reappear after disappearing in the first generation. The event of the reappearance of the first hereditary traits in the next generation after previously disappearing is referred to as the phenomenon of atavism.
Another example of atavism is the mating between fan-tailed pigeons, which will produce the first offspring in the form of a straight-tailed dove. Breeds of fan-tailed pigeons reappear after interbreeding with straight-tailed pigeons.
So, in principle atavism explains that a trait produced in the first generation will reappear in the next generation, although not in the second or third generation.
Thus the discussion this time about Mendel’s Laws of Perversion, hopefully useful for all friends J