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Mechanisms of Gene Expression 

One of the first as steps of understanding the connection between genetics and health is identifying the mechanisms of gene expression. By identifying genes whose variations are associated with different diseases, a better understanding of the linkage between genetics and health can be reached. 

Understanding the mechanisms of gene expression and how they are influenced by other genes, proteins, and the environment is becoming increasingly important. This knowledge aids in the development of preventive, diagnostic, and therapeutic strategies.

When genes are expressed, the chromosomal DNA must be transcribed into RNA. Then, the RNA is processed and transported and transferred into protein. The regulation of gene expression is an essential process in the cell. This process involves the organization of the chromosomal DNA into an appropriate higher-order chromatin structure. 

This process also involves the action of a host and particular protein factors. This can either promote or suppress the gene expression pathway. 

All organisms utilize networks of biochemical reactions and feedback signals to organize developmental pathways, cellular metabolism, and progression through the cell cycle. Feed-forward and feedback controls come from sets of pathways, which are dependent on earlier events. These lead to the overall coordination of the cell cycle and cellular metabolism. 

In these networks, gene expression is controlled by molecular signals that regulate when, where, and how often a given gene is transcribed. The molecular signals are typically stimulated by environmental influences or by signals from other cells that affect the gene expression of many genes through a single regulatory pathway. 

Complex branching networks of interactions are possible as a regulatory gene can act in combination with other signals to control many other genes.

Gene Expression and Regulation

By switching genes on or off when necessary, cells can respond to changes in the environment. This is evident with changes in diet and activity levels. Gene regulation is essential, since these responses can prevent resources from being wasted. 

Therefore, the variation in DNA sequences associated with the regulation of a gene’s expression are important for understanding gene-environment interactions at the molecular level. These variations will also affect whether an environmental signal transduced to the nucleus will successfully bind to the promoter sequence in the gene. This will either stimulate or repress gene expression. 

The combination of genomic technologies for SNP genotyping with high-density gene expression arrays in human studies has recently demonstrated the extent to which this type of molecular gene-environment interaction may happen.

Gene expression is also regulated by Combining Cells through post-transcriptional modification. This is done by allowing only a subset of the mRNAs to go on to translation or by restricting the translation of specific mRNAs to only when and where the product is needed.

It is much more difficult to study which genetic factors influence post-transcriptional control as they typically involve multiprotein complexes which are not easily retrieved or assayed from cells.

Gene expression is also regulated at other levels with cells through epigenetic mechanisms. This includes DNA folding, histone acetylation, and methylation or chemical modification of the nucleotide bases.These mechanisms are most likely influenced by genetic variations in the target genes as well as variations created in translated cellular regulatory proteins. 

It is also important to understand that gene regulation occurs during life at all levels of organismal development and aging. A common example of developmental control of gene expression is the distinctive expression of embryonic, fetal, and adult hemoglobin genes. Development signals tightly control the regulation of the epsilon, delta, gamma, alpha, and beta genes through DNA methylation. A large amount of genes are turned on and off through epigenetic regulation during development. 

The importance of regulation and gene expression has made genetics one of the fastest growing fields of study. One of the most popular areas of genetics is the study of the developmental consequences of environmental exposures on gene expression patterns and the impact of genetic variations on these developmental trajectories.

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