Biology 12 Unit 3: Heredity Protein Synthesis Transcription Also called RNA synthesis Similar to DNA synthesis except only one strand is produced, and it is an RNA strand mRNA, tRNA, and rRNA are required in the cytoplasm to direct protein synthesis 1. RNA Polymerase uncoils and unzips the DNA 2. Free RNA nucleotides bond to complimentary bases (A with T, U with A, C with G, and G with C) 3. RNA polymerase elongates the growing RNA strand Regulatory genes control which genes will be transcribed. Structural genes code for mRNA. Transcription Clip 1 Clip 2Clip 1 Clip 2 Translation The DNA strand in the nucleus acted as the template for the RNA strands in transcription The strand not read is the complementary strand - it is similar to the mRNA strand that was transcribed The code on the mRNA is comprised of groupings of three base pairs called a codon tRNA has a complimentary anticodon The tRNA is also bonded to an amino acid Clip 1 Clip 2 Protein SynthesisSynthesis THE CODE Complimentary Base Pairing DNA strand 1 ATGGTA DNA strand 2 TACCAT mRNA strand UACCAU tRNA strand AUGGUA Amino Acids MetVal Control of Gene Expression Lac and Trip OperonsLacTrip Mutation Electromagnetic Radiation, Chemicals, Viruses Substitution Nonsense, Silent Frame-shift Insertion, Deletion, Gene Recombination Genetic engineering takes advantage of natures enzymes. Restrictive enzymes cut the DNA into fragments, DNA ligases can then sew the strands back together, possibly with extra DNA fragments inserted. Clip Polymerase Chain Reaction