Gene Regulation Overview
The human body is an intricate, multi-stepped system that regulates itself through a process called homeostasis. An aspect of the human body that needs to be regulated is the expression of genes – whether expression is constant or only at certain times. The Human Genome Project (HGP) was a collaborative, international project that set out to sequence the whole human genome (National Human Genome Research Institute, 2015). It was completed in 2003 and approximately 99% of the human genome’s gene-containing regions are now known (National Human Genome Research Institute, 2015). It is now believed that there are 20 500 human genes within the genome and the locations of genes can now be located within the genome (National Human Genome Research Institute, 2015). These genes code for proteins that are needed in the body for a multitude of different purposes.
"It's a history book - a narrative of the journey of our species through time. It's a shop manual, with an incredibly detailed blueprint for building every human cell. And it's a transformative textbook of medicine, with insights that will give health care providers immense new powers to treat, prevent and cure disease." – Francis Collins, Director of NHGRI (2001)
Gene expression is both tissue and signal-specific and this is the central control for the properties of a cell as well as it’s response to environmental factors (Carlberg and Molnar, 2014). Because the human body is so multi-faceted, there is a lot of pre-knowledge that students need to know before they will understand how genes are regulated in both prokaryotes and eukaryotes. To ensure that students have this pre-knowledge, three units that should be taught are basic biochemistry, DNA structure and function and protein synthesis and genetic code, in this SNC4U course. Basic biochemistry will cover expectations B2.3, B3.2, B3.3, B3.4 and B3.5, the DNA structure and function unit will cover expectations D2.1, D2.4, D3.2, D3.3 and part of D3.5, and the unit on protein synthesis and genetic code covers expectations D2.2, D2.3, D3.1, D3.2 and D3.7. After students learn the concepts covered in these units, they will have a foundation to build upon with this unit about Controlling Gene Expression in Prokaryotes and Eukaryotes.
The following video is a very good overview of the significance of gene regulation within humans.
The control of genes is vital for proper function of cells within the body. Each cell carries DNA. Within eukaryotes it is found in the nucleus of the cell, but in prokaryotes, there is no nucleus, so it is just found freely in the cell. Every cell in a multi-cellular organism carries the same DNA, so some might wonder “How are cells in the body different from one another?” Gene regulation is crucial to ensure that cell differentiation occurs and the protein needed in certain cells are expressed when they are needed. A gut cell differs from a skin cell because of the genes that are expressed within each of those cells. Genes are expressed in some cells but not others based on the needs of that cell. The central dogma of microbiology indicates the flow of information from DNA to RNA to protein (Carlberg and Molnar, 2014), and this is true for both prokaryotes and eukaryotes. The product of transcription and translation within cells is proteins, which can be considered the workers of the cell. Proteins are responsible for metabolic control, transport of molecules, transduction of signals and a multitude of other processes (Carlberg and Molnar, 2014). Depending on whether the cell is a prokaryotic cell or a eukaryotic cell, the regulation that occurs is different – both mechanically and when the timing that regulation occurs.