Concept explainers
Write a one-sentence definition of the term "genotype." Do the same for "
Genome encompasses all the information essential for the survival of that organism. Genes are composed of DNA containing instructions either for coding a specific protein or to perform a specific function. Heritable modification in the nucleotide sequence of the genome that is passed from parent to next generation (progeny cells) is regarded as mutation. Such mutations may result in altering the characteristics of that organism. A virus or cell resulting from the wild-type that is carrying a modified DNA is regarded as the mutant.
Explanation of Solution
Genotype represents the entire set of genetic material (nucleotide sequence) of an organism.
Phenotype represents the noticeable properties of an organism.
A modification in the genotype of an organism do not always contribute to a change in its phenotype. Such alterations in the genotype might be due to point mutations. In general, point mutations do not necessarily alter the amino acid sequence (primary structure) of a protein. For example, the amino acid valine is encoded by the codon GUU and any change in the third nucleotide base also codes for valine. Thus, the product of the gene is not altered.
Upon placing an organism in a completely different environment, modifications in the phenotype occur and it is not often accompanied by a change in genotype. This modification in the phenotype could occur either due to the variations in the abiotic factors or genetic expression altering the gene product. For example, Serratia marcescens at 37° C – unpigmented; at 25° C – pigmented.
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Chapter 10 Solutions
Brock Biology of Microorganisms (14th Edition)
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