The Process of Gene Expression

Molecular genetics is the study how genes change overtime and the structure and function of genes at the molecular level. Evolutionary biologists had to make inferences based off of phenotypic observations before molecular genetics was established. We can use molecular genetics to prove evolution by how our genes and traits do change overtime due to diseases inherited from our parents, the environment we live in, both the actual living environment and the nutritional standpoint, and the lifestyle habits can affect our genes, which alter the future of evolutionary change. Darwin’s definition of theory is stated as the change in the genetic structure of population, frequently used to refer to the appearance of new species. Changes allow the organisms to better adapt to the environment, which in turn will help them survive and produce more offspring.

Transcription is the formation of an RNA strand from a DNA template within the nucleus of a cell. There are four nucleotides of DNA. These are adenine, cytosine, guanine and thymine. These nucleotides are transcribed to form messenger ribonucleic acid (mRNA) consisting of nucleotides made of adenine, cytosine, guanine and uracil. This transcription from DNA to mRNA happens by an RNA polymerase II. This newly created mRNA is read in the 5' to 3' direction in sets of 3. These sets are called codons. Each mRNA also has a cap and end. On the 5 prime side is a methylated guanine triphosphate and on the 3 prime is a poly A tail. Messenger RNA then moves to the cells cytoplasm and through the cells ribosomes for translation. Messenger RNA is matched to molecules of transfer RNA (tRNA) in the ribosomes to create amino acids. These amino acids subsequently form an amino acid chain. (Osuri, 2003) A visual representation of this can been viewed in figure 3.

1) DNA programs protein production in the cytoplasm by transferring its coded information to a molecule called RNA (mRNA). The RNA then carries the order to build this type of protein from the nucleus to the cytoplasm.

Since DNA has the instructions for making protein we usually wonder how is it able to make ribosomes if DNA is stored within the nucleus. This is when a handy tool comes in called transcription and copies the DNA into mRNA so it can be reached outside of the cell.

RNA processing: In eukaryotic cells, introns, non-coding regions of RNA, are removed and a tail and a cap is added to RNA to help its movement.

Transcription is a process in which genetic information from DNA is encoded onto messenger RNA, by unwinding the DNA and splicing exons and introns and coding them onto the mRNA so the DNA itself is not used directly. Translation is a process by which ribosomes reads the mRNA to determine the amino acid sequence of the protein.

It provides a base triplet, a sequence of three bases on one of the strands of DNA, that code for one amino acid. The sequence of base triplets on DNA molecules determines the order of the amino acids on the protein chain. In the first phase of transcription, the first process of protein synthesis that occurs in the nucleolus, a portion of a DNA molecule unwinds and serves as a template. Free nucleotides floating in the nucleoplasm pair up with their complimentary bases on the DNA strand.

The next two questions, “Why study bacterial gene regulation?” and “What are the basics of gene expression?” were addressed next in the seminar. Fascinatingly, a bacterial cell knows how to respond based on their environment. For example, they recognize and respond differently when in water than in a human. The average bacterial cell has close to 1000 genes, this is significantly more genetic information that they can use at any given time. These genes are stored in the DNA and each individual gene provides the information to make an individual product. So, how is a gene expressed? The first step in this process is called transcription. During transcription, the information encoded in the DNA is copied by RNA Polymerase to make mRNA. The next step is referred to as translation. During translation, the information in the mRNA is “translated” to make a protein using the ribosome. These steps basically turn genes “on and off” in a bacterial cell in response to a change in their environment. How does this happen? According to Dr. Henkin in her 2008

The central dogma of molecular biology states that DNA passes genetic information to RNA through a process called transcription and RNA uses the genetic information to code for proteins through a process called translation. Effects of cell differentiation can be seen at many points throughout this process, including in the proteins produced following translation. Differences in these proteins produced can be analyzed by looking at the enzymatic activity of the proteins. Analyzing enzymatic activity in proteins can be helpful in many situations, such as when analyzing how to fight certain diseases scientists could analyze the proteins that the diseased cells produce and then use that information to make medicines that can destroy those proteins to prevent the diseased

One of the fundamental discoveries of the 20th century was that DNA was the genetic code’s physical structure (Watson & Crick, 1953) and, since then, many studies have disclosed the complicated pattern of regulation and expression of genes, which involve RNA synthesis and its subsequent translation into proteins.

Transcription is where DNA is transcribed into RNA which then can be pass to the ribosome’s to act as a template for protein synthesis. Before transcription can begin DNA must unwind and the two halves of the molecule much come apart so exposing the base sequence. This process begins when a region of a two DNA strands is unzipped by enzyme called RNA polymerase attaches to the DNA molecule at the imitation site.

The formation of a protein begins in the genes, which contain the basic building information for all parts of living organisms. There are four DNA nucleotides that make up genes: A, T, C, and G. A codon is any arrangement of three of these nucleotides. Each triplet of nucleotides codes for one amino acid. First transcription will begin in the nucleus where mRNA will transcribe the DNA template. During both transcription and translation, there are three steps. The first step in transcription is initiation where RNA polymerase separates a DNA strand and binds RNA nucleotides to the DNA. RNA nucleotides are the same as DNA ones except that U replaces the T. The second is just the elongation of the mRNA. The third step of transcription is termination. This occurs when RNA polymerase reads a codon region and the mRNA separates from the

DNA and RNA form the basic unit of the living system. They are termed as the genome. Eukaryotic and prokaryotic genome undergoes two primary processes, transcription and translation. In transcription process, the protein nucleotides called exons gets converted into mRNA whereas, in the translation process, mRNA translated to proteins. In the human genome, 90% of the gene is junk DNA. Whole genome sequencing has revealed new aspects of gene expression, their role in living. Recent researchers have shown that there are some nonprotein coding RNAs are there which affects transcription, translation, post-translational modification and also affects the stability of the genome. Ther are two types of non-coding RNAs: one is regulatory

6. Correlation of genetic expression with clinicopathological variables, and prognosis in oscc among south Indian population – Wnt genes as possible biomarkers

In 2013, this system started being used (and is still widely used today) for adding and changing sequences of targeted genes (4), process also known as genome editing. The genome can be cut any location by guiding properly RNAs into a cell and also delivering Cas9 protein. In theory, it could be possible to build RNA-guided gene drives with the use of CRISPR to alter the genetic code of entire populations (5).