The San Rhine article titled “Genetic update Conferences 2010-11” provides the recent definitions that have emerged in the field of molecular biology, the new era of human genetics, personal genome analysis and, the aspect of regenerative medicine and tissue engineering. This article in general provides the current definitions that have emerged in molecular biology and other changes in its related field. In molecular biology, the author provides common definitions of terms like genome, gene, gene control, phenotype, and genotype. The author goes ahead to provide the new things that occurred in molecular biology with specific consideration on DNA and RNA replication.
From this article, one can be able to understand the meaning of a genome to mean the sum total of the genetic information of an organism expressed nucleotide pairs. Nucleotides in this case are the four bases of DNA, adenine (A), thymine (T), guanine (G), and cytosine (C). The same bases are present in RNA only that thymine is replaced by uracil (U). In DNA, adenine pairs with thymine while guanine pairs up with cytosine. The same pairing occurs in RNA where adenine pairs withy uracil while cytosine pairs with guanine.
DNA is double stranded having a deoxyribose sugar while RNA is single stranded having ribose sugar. The arrangement of the bases in both DNA and RNA as the author puts it starts from the 5’ end to the 3’ end.
The author defines a gene as a sequence of DNA responsible for the production of a particular protein molecule through the process of transcription and translation. A coding DNA gene carries the code for protein production. They are about 20,000 in humans and 57,000 in apples. All these processes occur in the ribosome of the cell. The process of gene expression start in the promoter site of a DNA leading to the formation of a transcript at the 5’ end and a poly A tail ant the 3’ end.
A human genome has both coding and non-coding regions known as exons and introns respectively. Introns must be removed because they do not code for any protein. The author also brings out the aspect of alternative splicing where 95% of genes have the capacity to have their own genes spliced to produce one protein. Some human coding genes can be nested or bidirectional.
The author also brings about the aspect of gene control through the existence of activators and repressors. Activators attach themselves to the promoters to initiate a positive genetic control while repressor initiates a negative control in the same promoter site.
In this article, the author provides the classical definitions of phenotype and genotype. A phenotype as presented here is the observable trait of an organism exemplified by hair color, blood type and eye color among others. A genotype on the other hand, is the DNA sequence usually of two alleles responsible for the expression of a phenotype.
AA or AO for instance are the genotype for blood group A, a phenotype. BB and BO is the Genotype for blood group B. the author however, provides the new definition for a genotype to mean the entire DNA sequence of an individual’s genome. The new definition of a phenotype is also provided which encompasses the modification of a genotype into an epigenotype, then to an epigenome, which later determines the phenotype.
The author also provides a comparison of genetics and epigenetics. Imprinting as provided in the article is a distinct type of epigenetic modification of the DNA involving both maternal and paternal genes.
Such modifications generally occur because of methylation, acetylation, and other epigenetic errors. The author also provides some of the fundamental terms used with the super suffix –ome.
These include the epigenome, transcriptome, proteome, interactome, exome, and introme. Epigenome for instance is the sum total on and off modifications of the chromatin while a transcriptome is the sum total of human transcripts.
Proteome is the sum total of human proteins, interactome being the sum total of all protein in interactions used in cancer prognosis, while exomes are the sum of all DNA coding sequences.
In relation to new changes in molecular biology, the author uses the example of DNA replication, transcription, and RNA replication. In the discovery of human nature, we are able to understand the fact that RNA comes DNA and RNA with the help of polymerases.
Life is a property of plants and animals characterized by the ability to metabolize, adapt, and self reproduce. The author also presents new developments in the field of human genetics. The use of a karyotype has made it possible for the identification of a locus of a gene. The gene for Alzheimer’s for instance is located at 10q24.1.
Genetics has also played an extremely pivotal role in medicine in the diagnosis of diseases. They include diseases like Down’s Syndrome, Turner’s Syndrome, and Klinefelter’s syndrome among others.
This is possible when understands the karyotype for the responsible genes. Some are however, hard to diagnose for example sickle cell anemia and retinitis pigmentosa among others. This is done using the Punnett Square. Complex genetic traits as the author puts it are multifactorial, and they include diabetes type 2, bipolar disorders, alcohol dependency among others.
The author also mentions of autoimmune diseases like diabetes type 1, multiple sclerosis and Psoriasis all, which are common but complex. Such diseases result from a limited number of individuals with the variant DNA responsible for the disease. The multifactorial diseases have been seen to occur along certain family lines, are rare, and sometimes involve some environmental factors. The author also brings about the aspect of heritability as a proportion of the phenotype variations for particular traits resulting from genetic differences.
Some traits are continuously distributed within the population leading to a bell-shaped curve. These include height, blood pressure, IQ, and blood glucose among others. The concept of quantitative traits and polygenes raises many questions relating to their number, their location, their role, and how they are controlled. The need to answer the questions resulted in the largest scientific project known as Human Genome Project, which involved the cooperation of twenty countries. This project started in 1990 and sought to study the human DNA. Other studies include the Genome Wide Association Studies, Comparative Genomic Hybridization, Genomic Investigation of ANthropomorhic Traits, the Pet Project, and Human Microbiome Project.
As the author ends the article, he provides some of the recent books that one can use a personal evaluation in relation to this topic. “The Language of Life” by Dr. Francis Collins serves best to widen one’s knowledge. The knowledge of genetics has been applied in regenerative medicine and tissue engineering. This involves the use of human tissues to repair the damaged ones. The engineering aspect involves a lab production of human tissue and its subsequent transfer to the body to replace the dysfunctional one. Tissue and organ sourcing involves the consideration of blood group compatibility and the Rhesus factor.
This brings about the autograft (self-tissue), isograft (equal, from twins), allograft (from a different person), and xenograft (from a different species). A biocompatible material is never rejected. Rejections of tissues occur because of the immune response. The sources of such tissues could be embryonic stem cells, adult stem cells, or induced pluripotent cells. Examples of tissue engineering include human skin equivalent, urinary bladder, nose, ear, jaw, finger, cornea, teeth, ligament, kidney, liver, and even the heart. Other possible stem cells include prostrate, adult mammary, and that of the rat. There are also future hopes of having a successful therapy for diabetes type 1, hand transplant, ovary transplant, and face transplants among others.