Metabolism and Energy Transformations in Body Cells - Renata Armenakovna Petrosova 2004

Template Synthesis Reactions. Transcription

The Genetic information for a protein is encoded as a nucleotide sequence within the DNA located in the Cell Nucleus, whereas actual Protein Synthesis takes place on Ribosomes in the Cytoplasm. Consequently, protein synthesis requires a carrier Structure to transport instructions from the DNA to the assembly site. This role is fulfilled by Messenger RNA (mRNA), which transfers genetic data from a specific DNA Gene to the ribosomes where protein synthesis occurs.

In addition to an information carrier, other molecules are essential to deliver Amino Acids to the synthesis site and determine their precise positions within the polypeptide chain. These molecules are Transfer RNAs (tRNAs), which facilitate amino acid encoding and delivery. Furthermore, because ribosomes—the sites of protein synthesis—are structurally composed of Ribosomal RNAs, yet another type of RNA is required, namely ribosomal RNA (rRNA).

Genetic information is expressed through three primary types of reactions: RNA Synthesis, protein synthesis, and METABOLISM/36.html">DNA Replication. In each of these processes, the information encoded in a linear nucleotide sequence is used to generate another linear sequence, consisting of either NUCLEOTIDES (in RNA or DNA molecules) or amino acids (in protein molecules). It has been experimentally proven that DNA serves as the template for the synthesis of all Nucleic Acids. These biosynthetic reactions are known as template-directed synthesis. Unlike many other cellular processes, the relative simplicity and unidimensional nature of template reactions have allowed researchers to thoroughly examine and understand their underlying mechanisms.