1. Protein Synthesis Traits are determined by proteins (often enzymes) *Protein – 1 or more polypeptide chains *Polypeptide – chain of amino acids linked by peptide bonds *One gene – one polypeptide (sort of)

2. The “Central Dogma” of Biology DNA  RNA  Protein (replication) (transcription) (translation) *the concept is basically right but modern biology is leading to an understanding of much more complexity

3. RNA Differs from DNA: 1.Sugar is ribose (has an OH off the 2’ carbon) 2.Uracil replaces thymine 3.Single stranded (usually)

4. Types of RNA in protein synthesis 1.Messenger RNA (mRNA) -triplet codons, long strand 2.Transfer RNA (tRNA) -small (70-80 nucleotides) -about 45 different ones -carry amino acids to ribosome on board

5. 3.Ribosomal RNA (rRNA) -together with proteins it makes up ribosomes -assembled in nucleolus -large and small subunits come together  ribosomes

6. Transcription 1.Initiation – RNA polymerase attaches to DNA at promoter region (beginning of gene – 3’ end) - unzips DNA strands 2. Elongation – RNA polymerase links RNA nucleotides -mRNA strand made 5’  3’ 3. Termination – mRNA strand breaks off from DNA template

8. RNA Splicing mRNA is processed before it leaves nucleus -portions not necessary for polypeptide production are removed Intron – portion of gene that does not code for anything -removed by RNA splicing Exon – segments that contain the info

11. The Genetic Code Almost universal –strong evidence for common ancestry Must be triplet: –20 amino acids  need at least 20 base combos –4 bases (A,U,G,C) 4 2 = 16 (No good!) 4 3 = 64 combos (sufficient, and also allows for redundancy)

12. Translation * mRNA is read, code is translated into polypeptide 1. Initiation – all of the below come together at 5’ end of mRNA at “start codon” (AUG) –small ribosome subunit –Large ribosome subunit –tRNA carrying methionine

14. 2.Elongation -ribosome moves down mRNA a codon at a time -at each mRNA codon a tRNA (with complementary anticodon): -temporarily binds -leaves its amino acid behind -breaks off -the amino acids are linked as a polypeptide chain (by peptide bonds)

16. 3. Termination -upon reaching a stop codon -ribosome units, mRNA, polypeptide separate