Essay --

Biology Information Flow The central dogma of biology is the information flow in cells from DNA to RNA to Proteins. Francis Crick was the first to describe it as the nature of information flow. The information passes in one direction from the DNA to an RNA copy of the gene, then that copy, directs the sequential assembly of amino acid chains that become protein. The DNA-to-RNA step is called transcription because an exact copy of DNA is produced. RNA-to-protein step is termed translation because it requires translation from the nucleic acid to protein. Transcription is the DNA’s direct synthesis of RNA by RNA polymerase. Since DNA is double stranded and RNA is single stranded, the principal of complementarity is used and only one of the two DNA strands needs to be copied. The copied strand is called the template strand and is complementary to the RNA transcription sequence. The one strand of the DNA that is not used is called the coding strand. RNA uses messenger RNA which is a direct synthesis of polypeptides. It carries DNA messages to the ribosomes for processing. Translation is more complex than transcription. Since the RNA has no complementarity it cannot be used as a direct template for a protein. The adapter molecule transfer RNA is used to interact with both RNA and amino acids. Translation occurs inside the ribosome and it requires participation from multiple kinds of RNA and proteins. Viruses called retroviruses were discovered during the formulation of the central dogma. This retrovirus comes from the environment and into the cell and back out through normal central dogma. The retro virus comes from the environment. First the viral enzyme reverse transcriptase takes the viral RNA genome and uses host nucleotides to co... ...lowing it to respond quickly to changes in their external environment by changing patterns quickly. Almost all the changes are reversible allowing the cell to adjust its enzyme levels in response to the environment changes. The gram-negative bacterium has pores on the outer membrane called porin. They are not like membrane transport, porins are large enough to allow passive diffusion. This is how the prolin amino acids outside of the cell in the environment could have entered. So once the abundance of proline is present in the gram-negative bacterium, it should bind to the repressor and then alter its confirmation so it now binds to DNA. The proline-repressor complex binds tightly to the operator, preventing RNA polymerase from initiating transcription. Work Cited Raven, Johnson, Mason, Losos, and Singer. Biology. 10th ed. N.p.: Mcgraw Hill Education, n.d. Print.