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Protein Synthesis. John Christmas Biology 101 Northern Virginia Community College. In prokaryotes, without a nucleus, mRNA produced by transcription from DNA is translated without further processing;
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Protein Synthesis John Christmas Biology 101 Northern Virginia Community College
In prokaryotes, without a nucleus, mRNA produced by transcription from DNA is translated without further processing; In eukaryotes, nucleus provides a compartment for transcription; pre-mRNA processed before leaving the nucleus. Roles of Transcription and Translation in Flow of Genetic Information
mRNA molecules are translated simultaneously by several ribosomes in clusters called polyribosomes, illustrated by the micrograph to the right; • Polyribosomes are found in both prokaryotic and eukaryotic cells.
Small ribosomal subunits bind to mRNA, with an initiator tRNA binding with the start codon; • The large ribosomal subunit arrives and complexes and the initiation of translation begins. Guanosine triphosphate (GTP) provides the energy.
Termination of Translation • When a ribosome reaches a termination codon on mRNA, a release factor is accepted rather than additional tRNA; • This hydrolyzes the bond of the amino acid at a tRNA binding site, the protein is freed from the ribosome, and the two ribosomal units and other components separate.
Messenger RNA (mRNA) is moved through a ribosome; There is translation of the mRNA into and amino acids sequence; Transfer RNA (tRNA) has an amino acid attached, and its anticodon bonds to a complementary codon on the mRNA. Basic Concept of Translation