In simple words, genome is the complete heredity material of an organism. Genome contains all the information that an organism requires to function. In eukaryotes, genome resides inside the nucleus while in prokaryotes, genome floats in the cytoplasm. Furthermore, the genome consists mainly of coding and non-coding DNA. Also, genes are present in the genome, and it occupies a small percentage from the total genome. Even within the genes, introns which are non-coding sequences can be seen.
Intergenic regions, promoter sequences, enhancers and regulatory sequences are the other types of sequences present in the genome of an organism. In humans, genome represents the 46 chromosomes. It is totally a DNA genome. It contains more than 3 billion base pairs of DNA. Most of the living organisms have DNA genomes. But there are RNA genomes as well. Some viruses have RNA genomes.
Gene pool is a collection of genes of a population or a species. Thus, it is a mixture of genes of a group of organisms. It does not represent a single organism. In fact, gene pool represents a group of organisms and total alleles of that particular population. Here, the alleles are alternative forms of a gene. Furthermore, the gene pool accounts all possible forms of the genes within the population.
Therefore, we can define the term gene pool as an abstract collection of a total of all existing variants of every gene of the population.
Moreover, every allele has a frequency within the gene pool. Hence, allele frequency can be used as a measure of evolution as well. Besides, in the evolutionary line, it is necessary to increase the favourable allele frequencies in the gene pool while eliminating the unfavourable alleles from it.
Moreover, gene flow and genetic drift are two possible things that can take place in a gene pool. Here, gene flow refers to the transfer of a gene from one gene pool of a population to another gene pool of a different population of the same species. While, genetic drift refers to a change in gene pool of a population by chance.
However, from both mechanisms, genes can move in and out from the gene pool. In plant breeding and plant improvement, gene pool is an important concept since it guides breeders to select germplasm for the hybridization. Genes are important since they contain the genetic information to produce proteins.
Genomes of organisms contain these genes. Thus, Genome is the complete set of the DNA of an organism that comprises the genetic information of the organism. In contrast, the gene pool is the whole collection of alleles in a population. Therefore, gene pool comprises the genetic information of a population. Hence, this is the prime difference between genome and gene pool. This means that the gene pool of a population is dynamic and can change at any moment for a variety of reasons.
In addition, the rate of change within a gene pool can vary at different points in time. From the perspective of a geneticist, a population is a group of organisms of the same species that interbreed. This may mean that the group of organisms all live in the same area, or that they can travel over long distances to mate.
Over time, a population's gene pool may change. A variety of different factors can account for these changes, including migration of new individuals into the population, death of a large number of individuals within the population, or environmental factors that favor certain traits over others.
This page appears in the following eBook. Aa Aa Aa. What is variation in a gene pool? Figure 1: The concept of a gene pool includes multiple alleles in a group of organisms. Figure 2: Genetic variation within three butterfly species. Three different butterfly species top row show distinct wing colors and patterns.
When individuals from the same three species are born in a different season, they each show different wing color and pattern phenotypes bottom row. This is a reflection of the variation that exists in the gene pool. Arashnia levana butterfly top row left has orange wings with black, square-shaped patches and spots. An Arashnia levana butterfly born under different temperature and light conditions bottom row left has black wings with white stripes and splotches.
A Precis octavia butterfly top row middle has orange wings with black edging, small black spots and black toward the center. A Precis octavia butterfly born under different temperature and light conditions bottom row middle has dark and light blue wings with square-shaped orange markings. A bicyclus anynana butterfly top row right has brown wings: its two anterior wings each have a large, dark, brown circular marking.
The marking has a thin orange outline and a white dot in the center; it looks like an owl's eye. Several similar, but smaller markings are visible on the two posterior wings. The wings of a Bicuclus anynana butterfly born under different temperature and light conditions bottom row right are a lighter brown color than the individual shown in the top row.
Tropical butterflies provide an excellent example of genetic variation within species. In these butterflies, temperature and light can influence gene expression. Consequently, wing color and pattern can vary depending on the season during which a butterfly is born.
The top row of Figure 2 shows examples of three different butterfly species. The bottom row shows butterflies from the same three species, but these individuals were born under different temperature and light conditions than those in the top row. How can this happen? The differences in wing colors and patterns of butterflies of the same species reflect the underlying genetic variability within a population. Even though each butterfly within a species has the potential to develop the wide variety of colors and patterns shown above, its environment influences the phenotypic expression of its genetic characteristics.
The gene pool of each species, therefore, contains a collection of many different alleles whose phenotype may or may not be observable. Can gene pools vary within populations? The factors that affect the composition of the gene pool are shaped both by the physical environment and by time. Consequently, the definition of populations can be refined to include groups of organisms whose genetic makeup can change over time, and groups of organisms that tend to interbreed.
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