1. Look at Dannyã¢â‚¬â„¢s Pedigree Again. What Is the Genotype of His Mother?

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

The genotype of an organism is its complete prepare of genetic material.^[1] Genotype tin can besides be used to refer to the alleles or variants an individual carries in a particular gene or genetic location.^[2] The number of alleles an individual tin can accept in a specific gene depends on the number of copies of each chromosome found in that species, too referred to as ploidy. In diploid species like humans, two full sets of chromosomes are present, meaning each private has two alleles for any given cistron. If both alleles are the same, the genotype is referred to every bit homozygous. If the alleles are different, the genotype is referred to as heterozygous.

Genotype contributes to phenotype, the observable traits and characteristics in an private or organism.^[three] The degree to which genotype affects phenotype depends on the trait. For case, the petal color in a pea plant is exclusively determined by genotype. The petals can exist purple or white depending on the alleles present in the pea found.^[four] Yet, other traits are only partially influenced by genotype. These traits are often called circuitous traits because they are influenced by additional factors, such equally ecology and epigenetic factors. Non all individuals with the aforementioned genotype wait or deed the same way because appearance and behavior are modified past ecology and growing conditions. Likewise, not all organisms that look alike necessarily have the same genotype.

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

Phenotype [edit]

Any given cistron will unremarkably cause an appreciable change in an organism, known as the phenotype. The terms genotype and phenotype are distinct for at least two reasons:

• To distinguish the source of an observer'south knowledge (one tin can know virtually genotype past observing Dna; i can know near phenotype by observing outward advent of an organism).
• Genotype and phenotype are not e'er straight correlated. Some genes only express a given phenotype in certain environmental atmospheric condition. Conversely, some phenotypes could be the upshot of multiple genotypes. The genotype is ordinarily mixed upward with the phenotype which describes the end event of both the genetic and the environmental factors giving the observed expression (due east.thou. blue eyes, hair color, or various hereditary diseases).

A elementary example to illustrate genotype equally distinct from phenotype is the flower colour in pea plants (meet Gregor Mendel). At that place are three available genotypes, PP (homozygous dominant ), Pp (heterozygous), and pp (homozygous recessive). All iii take different genotypes but the first two have the same phenotype (purple) as distinct from the third (white).

A more technical example to illustrate genotype is the unmarried-nucleotide polymorphism or SNP. A SNP occurs when corresponding sequences of DNA from unlike individuals differ at ane DNA base, for example where the sequence AAGCCTA changes to AAGCTTA.^{[half dozen]} This contains two alleles : C and T. SNPs typically have three genotypes, denoted generically AA Aa and aa. In the example in a higher place, the three genotypes would be CC, CT and TT. Other types of genetic marking, such equally microsatellites, tin can have more two alleles, and thus many different genotypes.

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

Mendelian inheritance [edit]

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

Traits that are adamant exclusively by genotype are typically inherited in a Mendelian pattern. These laws of inheritance were described extensively by Gregor Mendel, who performed experiments with pea plants to determine how traits were passed on from generation to generation.^[8] He studied phenotypes that were hands observed, such as institute height, petal color, or seed shape.^[8] He was able to observe that if he crossed ii true-breeding plants with distinct phenotypes, all the offspring would have the same phenotype. For example, when he crossed a tall plant with a short establish, all the resulting plants would be tall. Notwithstanding, when he self-fertilized the plants that resulted, well-nigh 1/4 of the second generation would exist brusque. He concluded that some traits were ascendant, such as tall summit, and others were recessive, like short meridian. Though Mendel was not aware at the time, each phenotype he studied was controlled by a single cistron with two alleles. In the case of constitute height, 1 allele caused the plants to be alpine, and the other caused plants to exist short. When the tall allele was present, the institute would be tall, even if the plant was heterozygous. In order for the plant to be short, it had to be homozygous for the recessive allele.^{[8] [9]}

Ane way this tin exist illustrated is using a Punnett square. In a Punnett square, the genotypes of the parents are placed on the outside. An uppercase letter is typically used to correspond the dominant allele, and a lowercase letter of the alphabet is used to represent the recessive allele. The possible genotypes of the offspring can then exist determined by combining the parent genotypes.^[10] In the example on the correct, both parents are heterozygous, with a genotype of Bb. The offspring tin can inherit a ascendant allele from each parent, making them homozygous with a genotype of BB. The offspring can 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 aforementioned, since the B allele is ascendant. The plant with the bb genotype will have the recessive trait.

These inheritance patterns can also be applied to hereditary diseases or conditions in humans or animals.^{[xi] [12] [13]} Some atmospheric condition are inherited in an autosomal dominant pattern, significant individuals with the condition typically take an affected parent as well. A archetype pedigree for an autosomal dominant status shows affected individuals in every generation.^{[11] [12] [thirteen]}

An example of a pedigree for an autosomal dominant status

Other atmospheric condition are inherited in an autosomal recessive pattern, where affected individuals practise not typically have an affected parent. Since each parent must have a copy of the recessive allele in society to have an affected offspring, the parents are referred to as carriers of the condition.^{[11] [12] [thirteen]} In autosomal conditions, the sex of the offspring does not play a role in their risk of being affected. In sex activity-linked conditions, the sex of the offspring affects their chances of having the condition. In humans, females inherit two Ten chromosomes, 1 from each parent, while males inherit an X chromosome from their female parent and a Y chromosome from their father. X-linked ascendant conditions tin can exist distinguished from autosomal dominant conditions in pedigrees by the lack of transmission from fathers to sons, since affected fathers only pass their X chromosome to their daughters.^{[13] [14] [15]} In 10-linked recessive conditions, males are typically affected more commonly because they are hemizygous, with only one X chromosome. In females, the presence of a 2nd Ten chromosome will forbid the condition from actualization. Females are therefore carriers of the condition and can laissez passer the trait on to their sons.^{[13] [14] [15]}

An example of a full-blooded for an autosomal recessive condition

Mendelian patterns of inheritance can be complicated by additional factors. Some diseases show incomplete penetrance, meaning not all individuals with the disease-causing allele develop signs or symptoms of the disease.^{[13] [xvi] [17]} Penetrance can also exist age-dependent, meaning signs or symptoms of disease are not visible until afterwards in life. For example, Huntington disease is an autosomal dominant condition, but upwards to 25% of individuals with the affected genotype volition not develop symptoms until afterward age fifty.^[18] Another factor that can complicate Mendelian inheritance patterns is variable expressivity, in which individuals with the aforementioned genotype show different signs or symptoms of disease.^{[thirteen] [16] [17]} For example, individuals with polydactyly tin can take a variable number of extra digits.^{[xvi] [17]}

Non-Mendelian inheritance [edit]

Many traits are not inherited in a Mendelian mode, just have more complex patterns of inheritance.

Incomplete authority [edit]

For some traits, neither allele is completely dominant. Heterozygotes often have an appearance somewhere in between those of homozygotes.^{[nineteen] [20]} For example, a cross between true-convenance reddish and white Mirabilis jalapa results in pink flowers.^[20]

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 claret grouping system in humans, where both the A and B alleles are expressed when they are nowadays. Individuals with the AB genotype take both A and B proteins expressed on their ruby blood cells.^{[21] [22]}

Epistasis [edit]

Epistasis is when the phenotype of 1 gene is affected by one or more other genes.^[23] This is often through some sort of masking effect of one factor on the other.^[24] For example, the "A" gene codes for hair color, a dominant "A" allele codes for brownish hair, and a recessive "a" allele codes for blonde hair, just a divide "B" gene controls pilus growth, and a recessive "b" allele causes alopecia. If the individual has the BB or Bb genotype, then they produce hair and the hair colour phenotype can be observed, merely if the individual has a bb genotype, and then the person is bald which masks the A factor entirely.

Polygenic traits [edit]

A polygenic trait is one whose phenotype is dependent on the condiment furnishings of multiple genes. The contributions of each of these genes are typically small and add together up to a final phenotype with a large corporeality of variation. A well studied example of this is the number of sensory bristles on a wing.^[25] These types of condiment effects is as well the explanation for the amount of variation in homo centre color.

Genotyping [edit]

Genotyping refers to the method used to determine an individual's genotype. There are a diverseness of techniques that tin be used to appraise genotype. The genotyping method typically depends on what information is being sought. Many techniques initially require amplification of the Dna sample, which is commonly washed using PCR.

Some techniques are designed to investigate specific SNPs or alleles in a particular cistron or set up of genes, such as whether an individual is a carrier for a detail condition. This tin can be washed via a diversity of techniques, including allele specific oligonucleotide (ASO) probes or Deoxyribonucleic acid sequencing.^{[26] [27]} Tools such as multiplex ligation-dependent probe amplification tin can too exist used to expect for duplications or deletions of genes or gene sections.^[27] Other techniques are meant to assess a big number of SNPs across the genome, such as SNP arrays.^{[26] [27]} This type of technology is commonly used for genome-wide association studies.

Big-calibration techniques to assess the entire genome are also available. This includes karyotyping to decide 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 be determined using exome sequencing, which provides the specific sequence of all DNA in the coding region of the genome, or whole genome sequencing, which sequences the entire genome including non-coding regions.^{[26] [27]}

See also [edit]

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

References [edit]

1. ^ "What is genotype? What is phenotype? – pgEd". pged.org . Retrieved 2020-06-22 .
2. ^ "Genotype". Genome.gov . Retrieved 2021-eleven-09 .
3. ^ Pierce, Benjamin (2020). Genetics A Conceptual Approach. NY, New York: Macmillian. ISBN978-one-319-29714-five.
4. ^ Alberts B, Bray D, Hopkin K, Johnson A, Lewis J, Raff Thousand, Roberts K, Walter P (2014). Essential Jail cell Biology (4th ed.). New York, NY: Garland Scientific discipline. p. 659. ISBN978-0-8153-4454-iv.
5. ^ Johannsen W (1903). "Om arvelighed i samfund og i rene linier". Oversigt Birdy over Det Kongelige Danske Videnskabernes Selskabs Forhandlingerm (in Danish). three: 247–lxx. German ed. "Erblichkeit in Populationen und in reinen Linien" (in German). Jena: Gustav Fischer. 1903. Archived from the original on 2009-05-thirty. Retrieved 2017-07-19 . . As well see his monograph Johannsen W (1905). Arvelighedslærens elementer horse [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 2017-07-19 .
6. ^ Vallente, R. U., PhD. (2020). Single Nucleotide Polymorphism. Salem Press Encyclopedia of Science.
7. ^ Allaby, Michael, ed. (2009). A lexicon of zoology (3rd ed.). Oxford: Oxford University Press. ISBN9780199233410. OCLC 260204631.
8. ^ ^{a b c} "Gregor Mendel and the Principles of Inheritance | Learn Scientific discipline at Scitable". www.nature.com . Retrieved 2021-eleven-15 .
9. ^ "12.1 Mendel's Experiments and the Laws of Probability - Biology | OpenStax". openstax.org . Retrieved 2021-eleven-15 .
10. ^ "3.6: Punnett Squares". Biology LibreTexts. 2016-09-21. Retrieved 2021-11-15 .
11. ^ ^{a b c} Alliance, Genetic; Health, District of Columbia Department of (2010-02-17). Archetype Mendelian Genetics (Patterns of Inheritance). Genetic Alliance.
12. ^ ^{a b c} "Mendelian Inheritance". Genome.gov . Retrieved 2021-11-xv .
13. ^ ^{a b c d e f yard} Strachan, T. (2018). Human molecular genetics. Andrew P. Read (fifth ed.). New York: Garland Science. ISBN978-0-429-82747-1. OCLC 1083018958.
14. ^ ^{a b} Alliance, Genetic; Health, Commune of Columbia Department of (2010-02-17). Classic Mendelian Genetics (Patterns of Inheritance). Genetic Alliance.
15. ^ ^{a b} "4.4.1: Inheritance patterns for Ten-linked and Y-linked genes". Biological science LibreTexts. 2020-06-24. Retrieved 2021-11-15 .
16. ^ ^{a b c} "xiv.2: Penetrance and Expressivity". Biological science LibreTexts. 2021-01-xiii. Retrieved 2021-xi-19 .
17. ^ ^{a b c} "Phenotype Variability: Penetrance and Expressivity | Learn Science at Scitable". www.nature.com . Retrieved 2021-xi-19 .
18. ^ Caron, Nicholas Due south.; Wright, Galen EB; Hayden, Michael R. (1993), Adam, Margaret P.; Ardinger, Holly H.; Pagon, Roberta A.; Wallace, Stephanie E. (eds.), "Huntington Illness", GeneReviews®, Seattle (WA): University of Washington, Seattle, PMID 20301482, retrieved 2021-11-19
19. ^ "Genetic Authority: Genotype-Phenotype Relationships | Learn Science at Scitable". www.nature.com . Retrieved 2021-eleven-15 .
20. ^ ^{a b} Frizzell, M.A. (2013), "Incomplete Dominance", Brenner'south Encyclopedia of Genetics, Elsevier, pp. 58–60, doi:10.1016/b978-0-12-374984-0.00784-1, ISBN978-0-08-096156-9 , retrieved 2021-11-xv
21. ^ ^{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-nine , retrieved 2021-eleven-fifteen
22. ^ "Genetic Dominance: Genotype-Phenotype Relationships | Acquire Science at Scitable". www.nature.com . Retrieved 2021-11-15 .
23. ^ Gros, Pierre-Alexis; Nagard, Hervé Le; Tenaillon, Olivier (2009-05-01). "The Evolution of Epistasis and Its Links With Genetic Robustness, Complexity and Drift in a Phenotypic Model of Adaptation". Genetics. 182 (1): 277–293. doi:x.1534/genetics.108.099127. ISSN 0016-6731. PMC2674823. PMID 19279327.
24. ^ Rieger, Rigomar. (1976). Glossary of genetics and cytogenetics : classical and molecular. Michaelis, Arnd,, Dark-green, Melvin M. (quaternary completely rev. ed.). Berlin: Springer-Verlag. ISBN0-387-07668-9. OCLC 2202589.
25. ^ Mackay, T. F. (December 1995). "The genetic ground of quantitative variation: numbers of sensory bristles of Drosophila melanogaster as a model organization". Trends in Genetics. 11 (12): 464–470. doi:10.1016/s0168-9525(00)89154-four. ISSN 0168-9525. PMID 8533161.
26. ^ ^{a b c d} Jain, Kewal K. (2015), Jain, Kewal K. (ed.), "Molecular Diagnostics in Personalized Medicine", Textbook of Personalized Medicine, New York, NY: Springer, pp. 35–89, doi:10.1007/978-1-4939-2553-7_2, ISBN978-1-4939-2553-seven , retrieved 2021-11-19
27. ^ ^{a b c d e} Wallace, Stephanie E.; Edible bean, Lora JH (2020-06-18). Educational Materials — Genetic Testing: Current Approaches. University of Washington, Seattle.

External links [edit]

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Source: https://en.wikipedia.org/wiki/Genotype

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