Is Genetic Makeup Same As Genotype

Part of the genetic makeup of a cell which determines one of its characteristics

The genotype of an organism is its complete gear up of genetic material.^[1] Genotype can also be used to refer to the alleles or variants an individual carries in a item factor or genetic location.^[ii] The number of alleles an private can accept in a specific gene depends on the number of copies of each chromosome found in that species, also referred to as ploidy. In diploid species like humans, two full sets of chromosomes are present, meaning each private has ii alleles for whatsoever given gene. If both alleles are the same, the genotype is referred to equally homozygous. If the alleles are different, the genotype is referred to as heterozygous.

Genotype contributes to phenotype, the observable traits and characteristics in an individual or organism.^[3] The degree to which genotype affects phenotype depends on the trait. For case, the petal color in a pea constitute is exclusively determined by genotype. The petals can exist majestic or white depending on the alleles present in the pea establish.^[4] Still, other traits are only partially influenced by genotype. These traits are often called complex traits because they are influenced by additional factors, such equally ecology and epigenetic factors. Not all individuals with the same genotype look or act the aforementioned way because appearance and behavior are modified by environmental and growing conditions. Likewise, not all organisms that look akin necessarily have the same genotype.

The term genotype was coined by the Danish botanist Wilhelm Johannsen in 1903.^[5]

Phenotype [edit]

Any given gene will usually cause an observable modify in an organism, known every bit the phenotype. The terms genotype and phenotype are distinct for at least 2 reasons:

To distinguish the source of an observer'southward knowledge (one can know most genotype by observing DNA; one can know nearly phenotype by observing outward appearance of an organism).
Genotype and phenotype are non always directly correlated. Some genes just limited a given phenotype in certain environmental conditions. Conversely, some phenotypes could exist the consequence of multiple genotypes. The genotype is commonly mixed upwardly with the phenotype which describes the cease effect of both the genetic and the environmental factors giving the observed expression (e.g. blue optics, pilus color, or various hereditary diseases).

A uncomplicated example to illustrate genotype as distinct from phenotype is the blossom colour in pea plants (run into Gregor Mendel). There are iii available genotypes, PP (homozygous ascendant ), Pp (heterozygous), and pp (homozygous recessive). All 3 have different genotypes just the first two have the same phenotype (purple) as distinct from the 3rd (white).

A more technical example to illustrate genotype is the unmarried-nucleotide polymorphism or SNP. A SNP occurs when corresponding sequences of DNA from different individuals differ at one Deoxyribonucleic acid base, for example where the sequence AAGCCTA changes to AAGCTTA.^[vi] This contains ii alleles : C and T. SNPs typically have three genotypes, denoted generically AA Aa and aa. In the instance above, the three genotypes would be CC, CT and TT. Other types of genetic marker, such as microsatellites, tin can accept more two alleles, and thus many different genotypes.

Penetrance is the proportion of individuals showing a specified genotype in their phenotype under a given set up of environmental conditions.^[vii]

Mendelian inheritance [edit]

Hither the relation between genotype and phenotype is illustrated, using a Punnett square, for the character of petal colour in a pea plant. The letters B and b represent alleles for colour and the pictures testify the resultant flowers. The diagram shows the cantankerous between two heterozygous parents where B represents the ascendant allele (purple) and b represents the recessive allele (white).

Traits that are determined exclusively by genotype are typically inherited in a Mendelian pattern. These laws of inheritance were described extensively past Gregor Mendel, who performed experiments with pea plants to determine how traits were passed on from generation to generation.^[eight] He studied phenotypes that were easily observed, such every bit plant height, petal colour, or seed shape.^[viii] He was able to observe that if he crossed two true-convenance plants with distinct phenotypes, all the offspring would have the aforementioned phenotype. For example, when he crossed a tall found with a brusk plant, all the resulting plants would be alpine. Yet, when he self-fertilized the plants that resulted, about 1/iv of the 2nd generation would be short. He concluded that some traits were dominant, such equally tall height, and others were recessive, like short superlative. Though Mendel was not aware at the time, each phenotype he studied was controlled by a single cistron with 2 alleles. In the case of found height, i allele acquired the plants to be tall, and the other acquired plants to be short. When the tall allele was present, the found would be tall, even if the plant was heterozygous. In order for the constitute to be short, it had to be homozygous for the recessive allele.^[8] ^[9]

Ane way this can be illustrated is using a Punnett square. In a Punnett square, the genotypes of the parents are placed on the outside. An uppercase alphabetic character is typically used to represent the dominant allele, and a lowercase letter is used to stand for the recessive allele. The possible genotypes of the offspring can so be determined past combining the parent genotypes.^[10] In the example on the right, both parents are heterozygous, with a genotype of Bb. The offspring can inherit a dominant allele from each parent, making them homozygous with a genotype of BB. The offspring tin inherit a dominant allele from one parent and a recessive allele from the other parent, making them heterozygous with a genotype of Bb. Finally, the offspring could inherit a recessive allele from each parent, making them homozygous with a genotype of bb. Plants with the BB and Bb genotypes will look the same, since the B allele is ascendant. The found with the bb genotype volition have the recessive trait.

These inheritance patterns can besides exist applied to hereditary diseases or conditions in humans or animals.^[11] ^[12] ^[13] Some conditions are inherited in an autosomal dominant design, meaning individuals with the condition typically have an affected parent as well. A classic pedigree for an autosomal ascendant condition shows affected individuals in every generation.^[11] ^[12] ^[13]

An case of a pedigree for an autosomal ascendant condition

Other conditions are inherited in an autosomal recessive pattern, where affected individuals practise non typically have an affected parent. Since each parent must take a copy of the recessive allele in club to take an affected offspring, the parents are referred to as carriers of the condition.^[xi] ^[12] ^[13] In autosomal conditions, the sex of the offspring does non play a function in their risk of existence affected. In sex-linked conditions, the sexual practice of the offspring affects their chances of having the condition. In humans, females inherit two X chromosomes, one from each parent, while males inherit an X chromosome from their female parent and a Y chromosome from their father. Ten-linked ascendant atmospheric condition tin can be distinguished from autosomal dominant conditions in pedigrees by the lack of transmission from fathers to sons, since affected fathers merely laissez passer their X chromosome to their daughters.^[xiii] ^[14] ^[xv] In X-linked recessive conditions, males are typically affected more commonly because they are hemizygous, with only one Ten chromosome. In females, the presence of a second X chromosome will forbid the status from actualization. Females are therefore carriers of the condition and can pass the trait on to their sons.^[13] ^[14] ^[15]

An instance of a pedigree for an autosomal recessive status

Mendelian patterns of inheritance can be complicated by additional factors. Some diseases show incomplete penetrance, pregnant not all individuals with the disease-causing allele develop signs or symptoms of the disease.^[thirteen] ^[xvi] ^[17] Penetrance can also be historic period-dependent, meaning signs or symptoms of disease are non visible until afterward in life. For case, Huntington disease is an autosomal dominant condition, but up to 25% of individuals with the affected genotype will non develop symptoms until after historic period 50.^[eighteen] Another factor that tin can complicate Mendelian inheritance patterns is variable expressivity, in which individuals with the same genotype testify different signs or symptoms of disease.^[13] ^[16] ^[17] For case, individuals with polydactyly tin can have a variable number of extra digits.^[xvi] ^[17]

Non-Mendelian inheritance [edit]

Many traits are not inherited in a Mendelian style, but accept more complex patterns of inheritance.

Incomplete dominance [edit]

For some traits, neither allele is completely ascendant. Heterozygotes oftentimes have an appearance somewhere in betwixt those of homozygotes.^[nineteen] ^[20] For example, a cross between true-breeding blood-red and white Mirabilis jalapa results in pinkish flowers.^[xx]

Codominance [edit]

Codominance refers to traits in which both alleles are expressed in the offspring in approximately equal amounts.^[21] A classic example is the ABO blood grouping system in humans, where both the A and B alleles are expressed when they are present. Individuals with the AB genotype have both A and B proteins expressed on their red blood cells.^[21] ^[22]

Epistasis [edit]

Epistasis is when the phenotype of i gene is affected by one or more other genes.^[23] This is often through some sort of masking effect of i gene on the other.^[24] For example, the "A" gene codes for hair colour, a ascendant "A" allele codes for chocolate-brown hair, and a recessive "a" allele codes for blonde hair, merely a separate "B" gene controls hair growth, and a recessive "b" allele causes baldness. If the private has the BB or Bb genotype, then they produce hair and the hair colour phenotype can exist observed, but if the individual has a bb genotype, and so the person is bald which masks the A gene entirely.

Polygenic traits [edit]

A polygenic trait is 1 whose phenotype is dependent on the additive furnishings of multiple genes. The contributions of each of these genes are typically small and add together upwardly to a final phenotype with a large amount of variation. A well studied case of this is the number of sensory bristles on a fly.^[25] These types of condiment effects is also the caption for the corporeality of variation in human middle color.

Genotyping [edit]

Genotyping refers to the method used to decide an individual'south genotype. In that location are a diverseness of techniques that can exist used to assess genotype. The genotyping method typically depends on what data is being sought. Many techniques initially require amplification of the DNA sample, which is unremarkably done using PCR.

Some techniques are designed to investigate specific SNPs or alleles in a particular cistron or set of genes, such as whether an individual is a carrier for a particular condition. This tin can be done via a variety of techniques, including allele specific oligonucleotide (ASO) probes or Dna sequencing.^[26] ^[27] Tools such as multiplex ligation-dependent probe amplification tin can also exist used to look for duplications or deletions of genes or gene sections.^[27] Other techniques are meant to assess a large number of SNPs across the genome, such as SNP arrays.^[26] ^[27] This type of technology is commonly used for genome-wide clan studies.

Large-scale techniques to appraise the entire genome are also available. This includes karyotyping to determine the number of chromosomes an individual has and chromosomal microarrays to assess for large duplications or deletions in the chromosome.^[26] ^[27] More detailed information can exist adamant using exome sequencing, which provides the specific sequence of all Deoxyribonucleic acid in the coding region of the genome, or whole genome sequencing, which sequences the entire genome including non-coding regions.^[26] ^[27]

Meet also [edit]

Endophenotype
Genotype–phenotype distinction
Nucleic acid sequence
Phenotype
Sequence (biology)

References [edit]

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^ Johannsen W (1903). "Om arvelighed i samfund og i rene linier". Oversigt Birdy over Det Kongelige Danske Videnskabernes Selskabs Forhandlingerm (in Danish). 3: 247–70. German ed. "Erblichkeit in Populationen und in reinen Linien" (in German). Jena: Gustav Fischer. 1903. Archived from the original on 2009-05-30. Retrieved 2017-07-19 . . Also run into his monograph Johannsen W (1905). Arvelighedslærens elementer equus caballus [The Elements of Heredity] (in Danish). Copenhagen. which was rewritten, enlarged and translated into German every bit Johannsen W (1905). Elemente der exakten Erblichkeitslehre (in German). Jena: Gustav Fischer. Archived from the original on 2009-05-30. Retrieved 2017-07-nineteen .
^ Vallente, R. U., PhD. (2020). Single Nucleotide Polymorphism. Salem Press Encyclopedia of Science.
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^ ^a ^b "4.iv.1: Inheritance patterns for 10-linked and Y-linked genes". Biology LibreTexts. 2020-06-24. Retrieved 2021-eleven-xv .
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^ "Genetic Dominance: Genotype-Phenotype Relationships | Learn Science at Scitable". www.nature.com . Retrieved 2021-11-15 .
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^ ^a ^b Xia, X. (2013), "Codominance", Brenner's Encyclopedia of Genetics, Elsevier, pp. 63–64, doi:10.1016/b978-0-12-374984-0.00278-3, ISBN978-0-08-096156-9 , retrieved 2021-11-15
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