Since the Austrian monk Gregor Mendel made breeding experiments by artificial selection with pea plants, understand how traits are transmitted from one generation to the next has been an important field of biology. Genetics is often used as a way to explain evolution , even if Charles Darwin didn’t know how it worked when he came up with the original Theory of Evolution. Over time, as society developed more technology, the marriage of evolution and genetics became apparent. Now, the field of Genetics is a very important part of the Modern Synthesis of the Theory of Evolution.
The Terms “Genotype” And “Phenotype”
To understand how genetics play a role in evolution, it is important to know the correct definitions of basic genetic terminology. Two of those terms that will be used repeatedly are genotype and phenotype . Although both terms have to do with the traits that individuals show, there are differences in their meanings.
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What Is A Genotype?
The word genotype comes from the Greek words “genos” which means “birth” and “typos” which means “mark”. While the whole word “genotype” does not exactly mean “birthmark” as we think of the phrase, it does have to do with the genetics that an individual is born with. A genotype is the actual genetic makeup or makeup of an organism.
Most genes are made up of two or more different alleles or forms of a trait. Two of those alleles join together to form the gene. That gene then expresses any dominant traits in the pair. It could also show a combination of those traits or show both traits equally, depending on the trait you are encoding. The combination of the two alleles is the genotype of an organism.
The genotype is often symbolized by two letters. A dominant allele would be symbolized by a capital letter, while the recessive allele would be represented by the same letter, but only in lowercase. For example, when Gregor Mendel did his experiments with pea plants, he saw that the flowers would be purple (the dominant trait) or white (the recessive trait). A purple-flowered pea plant may have the PP or Pp genotype. A white-flowered pea plant would have the pp genotype.
What Is A Phenotype?
The trait that is displayed due to coding in the genotype is called the phenotype . The phenotype is the actual physical characteristics that the organism displays. In pea plants, as in the example above, if the dominant allele for purple flowers is present in the genotype, then the phenotype would be purple. Even if the genotype had a purple allele and a recessive white allele, the phenotype would still be a purple flower. The dominant purple allele would mask the recessive white allele in this case.
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