In both prokaryotes and eukaryotes, transcription occurs in three main stages: initiation, elongation, and termination. The prokaryotes, which include bacteria and archaea, lack membrane-bound nuclei and other organelles, and transcription occurs in the cytoplasm of the cell. With the genes bound in the nucleus, transcription occurs in the nucleus of the cell and the mRNA transcript must be transported to the cytoplasm. Transcription: from DNA to mRNAīoth prokaryotes and eukaryotes perform fundamentally the same process of transcription, with the important difference of the membrane-bound nucleus in eukaryotes. However, as we shall see in the next module, the translation to protein is still systematic, such that nucleotides 1 to 3 correspond to amino acid 1, nucleotides 4 to 6 correspond to amino acid 2, and so on. The translation to protein is more complex because groups of three mRNA nucleotides correspond to one amino acid of the protein sequence.
The copying of DNA to mRNA is relatively straightforward, with one nucleotide being added to the mRNA strand for every complementary nucleotide read in the DNA strand. Figure 9.14 The central dogma states that DNA encodes RNA, which in turn encodes protein. The flow of genetic information in cells from DNA to mRNA to protein is described by the central dogma ( Figure 9.14), which states that genes specify the sequences of mRNAs, which in turn specify the sequences of proteins. The Central Dogma: DNA Encodes RNA RNA Encodes Protein This module discusses the details of transcription. Through the processes of transcription and translation, a protein is built with a specific sequence of amino acids that was originally encoded in the DNA.
#TRANSCRIBE BIOLOGY CODE#
The mRNA then provides the code to form a protein by a process called translation. To do this, the DNA is “read” or transcribed into an mRNA molecule. In both prokaryotes and eukaryotes, the second function of DNA (the first was replication) is to provide the information needed to construct the proteins necessary so that the cell can perform all of its functions. Describe how eukaryotic mRNA is processed.
Explain the main steps of transcription.By the end of this section, you will be able to:
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