Gene Expression Begins 1. The central dogma of molecular biology states that in the cell, DNA is transcribed into RNA, which is translated into protein. A DNA gene sequence is transcribed into RNA, which is a single-stranded nucleic acid with ribose instead of deoxyribose and uracil instead of thymine . 5.Transcription proceeds 5' to 3' as RNA polymerase inserts complementary RNA bases opposite one template strand of the DNA double helix. Each three mRNA bases in a row specify a codon.
Ribosomes physically support the other participants in protein synthesis.
One end of a tRNA molecule is complementary to a particular mRNA codon, and the other end is bound to the amino acid that the mRNA codon specifies. As translation begins, mRNA, tRNA with bound amino acids, ribosomes, energy molecules, and protein factors assemble. In elongation, peptide bonds form between the two amino acids attached to the two aligned tRNA molecules, building up a polypeptide. When a stop codon is reached, protein synthesis halts. The synthesized protein folds up as translation proceeds.