1. DNA Transcription & Protein Translation

2. DNA Transcription DNA must be copied to messenger RNA (mRNA) in the nucleus mRNA travels from nucleus to the ribosomes in cytoplasm Every set of three bases on mRNA is called a codon Remember RNA has uracil (U) instead of thymine (T), it has one strand and it contains the sugar ribose, not deoxyribose!

3. Transcription – Step I A C G T A T C G C G T A T G C A T A G C G C A T DNA Strands

4. Transcription – Step II A C G T A T C G C G T A U G C A U A G C G C A U One side of the DNA is Matched Up with a Complementary mRNA strand

5. Transcription – Step III mRNA leaves nucleus and goes to ribosomes U G C A U A G C G C A U A new complementary RNA strand is made for the other side of the DNA A C G U A U C G C G U A

6. Transcription Reminders The template strand is the DNA strand being copied The rRNA strand is the same as the DNA strand except Us have replaced Ts

7. Protein Translation Modified genetic code is “translated” into proteins tRNA matches the codons (set of 3 bases on the mRNA) with its own set of three bases (anticodon) Each piece of tRNA brings in an amino acid – 20 amino acids

8. tRNA in cytoplasm has a codon attached to an amino acid

9. tRNA structure 3-base code (triplet) is an “anticodon” Protein molecule Attached amino acid that is carried from cytoplasm to ribosomes

10. Protein Synthesis Start: Ribosome binds to mRNA at start codon (AUG) Elongation: – tRNA complexes bind to mRNA codon by forming complementary base pairs with the tRNA anticodon – The ribosome moves from codon to codon along the mRNA. – Amino acids are added one by one Release: release factor binds to the stop codon