Phenotype Vs. Genotype Overview

Phenotype Definition

The word “phenotype” describes all the features that may be seen in an organism due to the interaction between its genotype and its environment.

• The word “pheno” means to “observe,” hence it is used to describe an organism’s observable traits, such as its height and color.
• An organism’s phenotype includes its shape, physical make-up and composition, growth and behavior, biological and physiological characteristics, and even the output of the organism.
• Phenotypes are employed to determine the variations in DNA sequences across people with different features like height.
• An organism’s genotype, or how its genome is expressed and interacts with its environment or environmental factors, determines its phenotype.
• The phenotype of an organism may be caused by one, both, or both of the factors.
• Due to morphological, physiological, and environmental changes brought on by aging, variation in phenotype is seen even within one person.
• Natural selection, when the ecosystem encourages the survival of fitter people over less fit ones, is based on a variety of phenotypes.
• Twins are an excellent example of this phenomenon since identical twins can have distinct phenotypes depending on the environment they are exposed to.
• Therefore, evolution via natural selection is impossible without phenotypic diversity.
• A change in phenotype might have effects regardless of an individual’s genetic makeup. This is illustrated by silent mutations, which do not affect the amino acid sequences but change the frequency of guanine-cytosine base pairs.
• This change modifies the G-C ratio in the genome, enhancing thermal stability and allowing the organism to thrive in high-temperature environments.
• Blood type, eye color, hair texture, inherited diseases in humans, pod size and leaf color, bird beaks, etc., are some instances of phenotypes presented by many species.

Genotype Definition

An individual’s genetic makeup, which consists of heritable genes, is referred to as the genotype in the study of genetics.

• The two alleles inherited for a particular gene are commonly known as an individual’s genotype.
• The dominant allele in a genotype is denoted by the letter B, while the recessive allele is denoted by the letter b.
• The expression of these genes defines a person’s phenotypes or physical characteristics.
• The phenotype, however, is influenced by a variety of variables, including inherited epigenetics and environmental influences, and is not only determined by genotype.
• Consequently, neither all individuals with a similar genotype nor others with similar appearances contain the same genotype.
• Numerous variables, like mutations that modify the incidence of base pairs or the structure of DNA sequences, affect the frequency of base pairs and have an impact on an organism’s genotype.
• However, an individual’s genotype does not include genes created by a somatic mutation, which is acquired as opposed to inherited. Additionally, the genotypes are unaffected by these alterations.
• The genotype’s genetic makeup affects how it is expressed in living things. Children will always inherit the dominant characteristics irrespective of the other allele when a dominant allele is present.
• Except for occasional heritable mutations, the genotype of a character is completely governed by the gene sequences.
• Thus, unless mutated, a person’s genotype does not change throughout their lifetime.
• Similar to how genotype is unaffected by phenotype, phenotypic changes in an individual do not result in any changes to genotype.
• Like phenotypes, genotypes cannot be seen from the outside. Instead, techniques like genotyping should be used.
• Genotyping is the method that determines a person’s genotype, and it has a range of applications, such as PCR, DNA sequencing, and restriction fragment length polymorphism (RFLP).
• Multiple species exhibit the genotypes TT, which is the homozygous allele for height; Tt, which is the heterozygous allele for height; and BB, which is the homozygous allele for eye color.

Examples of phenotype

Melanin production

• Specific genes govern human melanin synthesis; hence, changes in melanin synthesis are due to differences in genotype.
• Despite the fact that numerous genes affect how much melanin is dispersed all over the body, just one gene influences how much is created.
• Consequently, individuals with a specific genotype may develop albinism due to the lack of melanin production.
• Consequently, albinos exhibit skin that is usually white or pink in color.
• Due to the fact that albinism is a phenotype that a specific genotype may induce and contains a large gene pool, it is prevalent in several groups.
• Some animals may even have a high prevalence of albinism.

Mendels’ Peas

• Mendel investigated many pea phenotypes as part of his research.
• These characteristics served as the basis for nearly every one of his findings.
• In the case of the peas’ hue, green and yellow-colored peas were studied. He observed that crossing yellow and green peas yielded peas with equal proportions of each color. With considerable fluctuation between generations.
• He calculated the ratios of various traits in many generations using this information.
• A specific gene that codes for color produces the yellow hue in peas. The color of the pea turned green while this gene was absent.
• As a consequence, the color green is the recessive allele, while the color yellow is the dominant allele.

Examples of a genotype

Eye Color

• BB is the dominant genotype for brown eyes, a dominant heritable trait.
• In homozygous individuals, the genotype for eye color will be BB or bb.
• All other eye colors, including blue, green, and grey, are recessive traits that are exclusive to homozygous-recessive (bb) people.
• If the genotype is homozygous, the eye color genes on the two chromosomal sites should be identical.
• The phenotype of an individual, or the color of their eyes, is determined by their genotype for that attribute.

Curly hair

• The genotype for curly hair would be HH or Hh if the dominant trait for hair type is H and the recessive trait is H.
• This genotype encodes the protein responsible for curly hair.
• If the genotype is HH, the individual will have curly hair. However, if the genotype is heterozygous, the individual will have wavy hair between curly and straight hair.
• Given that straight hair is a recessive trait, the genotype hh would be required for the hair to be straight.
• The curly hair trait is completely dominant in individuals with the heterozygous situation.

References and Sources

• 2% – https://biodifferences.com/difference-between-phenotype-and-genotype.html
• 1% – https://www.britannica.com/science/phenotype
• 1% – https://www.biologyonline.com/dictionary/phenotype
• 1% – https://en.wikipedia.org/wiki/Phenotype
• 1% – https://en.wikipedia.org/wiki/Genotype
• 1% – https://byjus.com/biology/genotype-and-phenotype-difference/
• <1% – https://www.spectrumnews.org/news/genetics-identical-twins-not-so-similar/
• <1% – https://www.slideshare.net/SRMegh/silent-mutation-2
• <1% – https://www.researchgate.net/publication/329214501_Biparental_Inheritance_of_Mitochondrial_DNA_in_Humans
• <1% – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3563493/
• <1% – https://www.ncbi.nlm.nih.gov/books/NBK7908/
• <1% – https://quizlet.com/361810829/chapter-22-and-23-darwin-flash-cards/
• <1% – https://quizlet.com/359071278/genetics-ch-1-flash-cards/
• <1% – https://quizlet.com/25549586/genetics-flash-cards/
• <1% – https://quizlet.com/114950720/ch-15-ch-16-study-guide-flash-cards/
• <1% – https://curlybetty.wordpress.com/2011/05/10/curly-hair-genetics-heredity/
• <1% – https://biologywise.com/homozygous-vs-heterozygous