Intro(10mins)
Bacteria belongs to a group of organism that lacks cell nucleus and membrane bound organells. This group of organisms are termed as prokaryotes. Prokaryotes follows the central dogma of molecular biology first proposed by Francis Crick in 1958 to synthesize proteins from mRNA through a process called translation and the mRNA is being synthesized from the DNA by another process called Transcription. Temperature, nutrient availibity are some key factors that start the process of synthesizing proteins in response to these key factors. Example. This paper will provide an explanation as to how bacteria decode the genetic information to produce proteins.
Transription generates 3 kinds of RNA. Transfer RNA(tRNA) carries amino acid during protein synthesis, ribosomal RNA molecules come together to form ribosomes while mRNA bears the message for protein synthesis. In bacteria, mRNA often carries coding information of more than 1 gene therefore it is said to be polycistronic (DIAGRAM).
MRNA is synthesized under the direction of DNA by RNA polymerase. This polymerase in its core enzyme form has 5 subunits. A 6th subunit called the Sigma factor helps the core enzyme to recognise and bind to the promoter regions which are often found at -35 basepair and -10 basepair(also called Pribnow box) upstream of the transcription site. Upon binding, RNA polymerase unwinds the helical DNA and this open region becomes a open complex. There is a reason as to why the -10bp site is chosen. The hydrogen bonds between the nucleotides in the Pribnow box are weak and easily broken, forming the open complex. RNA polymerase progresses along the DNA unwound DNA strand and starts to synthesize mRNA in the 5` to 3` direction. MRNA synthesized is thus complementary and anti parallel to the template DNA.
Termination of transcription require a terminator. There are two kinds of terminator,