.One pursuit of scientists in the field of biology is determining the common inheritance of all living things. Many problems exist in this pursuit. Among them are the following, according to Alberts et al.:
These three factors amongst others compromise scientists’ ability to determine the common inheritance of all living things. In fact, two of the major factors of evolution for prokaryotes are lineage-specific gene loss and horizontal gene transfer (Alberts et al. 2014).
Because of the many difficulties associated with the enterprise of determining the common inheritance of all living things, scientists have concluded that it appears that only a small proportion of ancestral gene families has been retained universally in a form that is recognizable. Specifically, only 63 gene families appear to be truly universal (represented in all of the genomes analyzed) out of 4,873 protein-coding gene families in which the genomes of 50 species of bacteria, 13 archaea, and 3 unicellular eukaryotes were compared. The universal families noted here were involved in translation and transcription systems, primarily (Alberts et al. 2014).
However, a broader view holds that an ancestral gene set can be better approximated by looking at the gene families that have representatives in multiple different species from all three major domains, but not necessarily in all species of all domains. When looking at things this way, there are 264 ancient conserved families. Scientists have been able to assign each family a function in terms of general biochemical activity. Scientists have discovered, through this, that the largest number of shared gene families are involved in translation and in amino acid metabolism and transport (Alberts et al. 2014).
Bear in mind, with all of this, that all of this information merely comprises a rough sketch of the common inheritance of all modern life. By no means is all of this precise. Hopefully, with advancements in biological technologies and techniques for examination, a more concrete view of this topic can be constructed with time (Alberts et al. 2014).
In this quick and simple post, I will just touch on one important topic. When deducing family relationships between genes, scientists also uncover more about a gene’s function. Determining the sequence of a gene allows scientists in many cases to determine the function of a gene. Nowadays, computer databases exist wherein gene sequences are logged and stored. With just a few steps, a scientist can find genes related to a particular gene, with the use of such databases. With ongoing research over time, the function of many genes have already been determined experimentally, and this information is often widely available. Gene sequence determines gene function, so when the function of one homolog is known, a guess can often be made at the function of another gene when the gene is similar to a known homolog. With the power of technology, more and more of the biology of an organism is becoming discoverable (Alberts et al. 2014).
Amongst topics in biology in which transmission of genetic material from parent to progeny is discussed is sexual reproduction. We may all have an understanding of the vertical transfer of genetic information from parent to offspring that occurs with sexual reproduction, but it is worth noting that horizontal gene transfer also occurs with sexual reproduction. The horizontal gene transfer occurs between the separate cell lineages of the mother and the father. As you might have learned already, this genetic exchange typically only occurs between members of the same species, i.e. humans to humans, dogs to dogs, etc. In this type of gene transfer, the result is individuals who are more closely related to one set of relatives with respect to some genes, and the same for another set of relatives with respect to other genes (Alberts et al. 2014).
Sexual production is common in many organisms across history. Even bacteria engage in a form of sexual reproduction from time to time, of course with members of their own species. Sexual reproduction is extremely common among eukaryotes. However, like most things, it is not universal. Scientific knowledge has it that natural selection has favored organisms that engage in sexual reproduction. However, as of right now, evolutionary theorists have not agreed on what the precise selective advantage is for those organisms (Alberts et al. 2014).
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