Explain the concept of inheritance and its types with suitable example of each of them.
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Incomplete dominance: where heterozygotes have an intermediate phenotype in-between the two homozygous phenotypes. An example is petal color in four-o’clock flowers, where homozygotes are either white or red, and heterozygotes are pink. Each R allele contributes one ‘unit’ of petal color, while each r allele contributes no ‘units’ of petal color. So two R alleles results in a red, one R allele results in pink, and no R alleles results in white.
Co-dominance: where heterozygotes display each phenotype associated with each allele. An example is AB blood type in humans, where the A allele results in one specific type of sugar on a red blood cell, and B results in a different type of sugar on a red blood cell. Two A alleles results in only A-type sugars, two B alleles results in only B-type sugars, and the heterozygote has both A- and B-type sugars on the red blood cell. (Type O results in no sugar; we’ll discuss this more in class.) Though they seem similar at first glance, incomplete dominance and co-dominance are different from each other, and are based on the molecular phenomenon underlying the trait.
Quantitative traits: where the trait has a continuous phenotype controlled by additive alleles at multiple genes. This means that the trait is not controlled by just one gene with several alleles, but MULTIPLE genes (polygenic inheritance), each of which can have multiple alleles. An example is human height: we have differences in height down to fractions of an inch, rather than being either 4 ft, 5 ft, or 6ft tall. Each height allele at each gene controlling height contributes a ‘unit’ of height which is additive. Quantitative traits are in contrast to discrete traits where the trait has only a few possible phenotypes which fall into discrete classes (ie, peas are either round or wrinkly, and there are no in-between phenotypes).
Multiple allelism: where a particular gene has more than two alleles. An example is human blood type (described above) where the single gene controlling blood type can be have an A, B, or O allele.
Gene-by-gene interactions: where the phenotype associated with one allele depends on the allele(s) present at another gene. This is different from a quantitative trait where alleles at multiple genes are additive. The gene-by-gene inheritance pattern can also be called epistasis. The take home-message on gene-by-gene interactions is that this phenomenon alters the expected phenotypic ratios of a Mendelian dihybrid cross (9:3:3:1) to a different pattern.
Pleiotropy is the phenomenon where a single gene influences multiple, seemingly unrelated traits. For example, in the human disorder phenylketonuria (PKU), a single mutation in a single gene can cause intellectual disability, seizures, reduced skin pigmentation, hair color, “musty” smelling urine, and a predisposition to eczema.
Gene by environment interactions: where the environment plays a role in determining phenotypecontrolled by alleles. An example is human height (which is also an example of a quantitative trait) where childhood nutrition plays a role in an adult height. We have gotten taller as a species in the last 200 years (mostly) not because of changes in our alleles but due to access to better nutrition in much of the world.
. .......I hope this will help you......if it is make me brainliest
Co-dominance: where heterozygotes display each phenotype associated with each allele. An example is AB blood type in humans, where the A allele results in one specific type of sugar on a red blood cell, and B results in a different type of sugar on a red blood cell. Two A alleles results in only A-type sugars, two B alleles results in only B-type sugars, and the heterozygote has both A- and B-type sugars on the red blood cell. (Type O results in no sugar; we’ll discuss this more in class.) Though they seem similar at first glance, incomplete dominance and co-dominance are different from each other, and are based on the molecular phenomenon underlying the trait.
Quantitative traits: where the trait has a continuous phenotype controlled by additive alleles at multiple genes. This means that the trait is not controlled by just one gene with several alleles, but MULTIPLE genes (polygenic inheritance), each of which can have multiple alleles. An example is human height: we have differences in height down to fractions of an inch, rather than being either 4 ft, 5 ft, or 6ft tall. Each height allele at each gene controlling height contributes a ‘unit’ of height which is additive. Quantitative traits are in contrast to discrete traits where the trait has only a few possible phenotypes which fall into discrete classes (ie, peas are either round or wrinkly, and there are no in-between phenotypes).
Multiple allelism: where a particular gene has more than two alleles. An example is human blood type (described above) where the single gene controlling blood type can be have an A, B, or O allele.
Gene-by-gene interactions: where the phenotype associated with one allele depends on the allele(s) present at another gene. This is different from a quantitative trait where alleles at multiple genes are additive. The gene-by-gene inheritance pattern can also be called epistasis. The take home-message on gene-by-gene interactions is that this phenomenon alters the expected phenotypic ratios of a Mendelian dihybrid cross (9:3:3:1) to a different pattern.
Pleiotropy is the phenomenon where a single gene influences multiple, seemingly unrelated traits. For example, in the human disorder phenylketonuria (PKU), a single mutation in a single gene can cause intellectual disability, seizures, reduced skin pigmentation, hair color, “musty” smelling urine, and a predisposition to eczema.
Gene by environment interactions: where the environment plays a role in determining phenotypecontrolled by alleles. An example is human height (which is also an example of a quantitative trait) where childhood nutrition plays a role in an adult height. We have gotten taller as a species in the last 200 years (mostly) not because of changes in our alleles but due to access to better nutrition in much of the world.
. .......I hope this will help you......if it is make me brainliest
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