1. DNA transcribes RNA RNA translates to protein
Protein Translation
DNA transcribes RNA
RNA translates to protein

2. Today’s Objectives
Investigate and understand common mechanisms of protein synthesis.

3. Transcription DNA must be copied to messenger RNA (mRNA)
mRNA goes from nucleus to the ribosomes in cytoplasm
mRNA complements known as codons
Only 3 nucleotide “letters” long
Remember RNA has uracil (U) instead of thymine (T)!
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Transcription

4. Transcription Reminders
The template strand is the DNA strand being copied
Transcription Reminders

5. Modified genetic code is “translated” into proteins
Codon code is specific, but redundant!
20 amino acids
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Protein Translation

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

7. Protein Synthesis Overview
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1. The DNA unzips 2.The mRNA reads the code off the DNA; transcription 3.mRNA moves out of the nucleus into the cytoplasm and attaches to the ribosome
4. Start: Ribosome binds to mRNA at start codon (AUG)
5. 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
6. Release: release factor binds to the stop codon