Chapter 14 - How Genes Work (DNA to Protein)

DNA -----transcription---> RNA -----translation----> protein

Transcription

• DNA to RNA
• in the nucleus
• only one DNA strand is transcribed
• only a small portion of the DNA is transcribed (a gene)
• uses RNA polymerase
• all 3 types of RNA are made this way
• process
  1. DNA unwinds
  2. complementary base pairing by RNA nucleotides to template strand
  3. enzyme adds nucleotides one by one to the growing RNA strand
  4. RNA is released
  5. DNA re-winds
• 3 kinds of RNA
  1. mRNA
  2. rRNA
  3. tRNA

Translation

• mRNA to protein (rRNA and tRNA are also used)
• in the cytoplasm
• the mRNA genetic code is read in sets of 3 nucleotides (codon)
• each codon specifies only one amino acid, but there may be several codons specifying the same amino acid
• ribosomes read the RNA and assemble the protein from amino acids
• process of translation

More Information

Science Odyssey's DNA Workshop

© Carol L. Wymer, 2004