4 Amino Acids - Summary Zwitterions Acid / Base Chemistry (Buffers) Optical Isomerism – chiral centre, CORNPeptide – Secondary AmidesNaming dipeptides – NH2 on leftHydrolysis of peptidesCondensation to form polypeptides and proteins
7 Protein Structure 4 levels of structure:- Primary Structure – Sequence of Amino Acids;Secondary Structure – Spatial arrangement of sections of primary Structure (e.g. helices);Tertiary Structure – Overall 3D Shape of protein;Quaternary Structure – Protein “Monomers” coordinated into tetramers (haemoglobin), or hexamers (insulin).
13 Building Proteins Cells adopt a similar approach – Protein Synthesis. Cells build proteins directly from L-Amino Acids.To synthesise a protein, a Chemist would need:-Instructions / knowledge of the primary structure;Supplies of pure amino acids;A method of forming peptide links.Cells adopt a similar approach – Protein Synthesis.
14 Protein synthesis – The role of RNA Messenger RNA - Temporary set of instructions for one protein molecule;2) Transfer RNA – collects amino acids;3) Ribosomal RNA – present in ribosomes, which catalyse the formation of peptide links between amino acids.
30 Transcription – in the nucleus 1) DNA double helix unwinds;2) hydrogen bonds break;3) free nucleotides hydrogen bond to the complementary exposed bases;4) Enzyme (RNA polymerase) links the hydrogen bonded nucleotides to form a strand of mRNA;5) mRNA is released and the DNA double helix is reformed.
31 How Cells Make Proteins Protein ChainDNAmRNATranscriptionTranslationa.a. activation
35 Translation - in the cytoplasm mRNA attaches to ribosome;Hydrogen bonding between complementary bases binds the correct tRNA anticodon to the 1st codon (set of 3 bases on mRNA);A 2nd tRNA – amino acid complex binds to the adjacent mRNA codon in the ribosome;Ribosome catalyses the formation of the peptide bond between amino acids;The tRNA is released once the amino acid is delivered;Ribosome moves along the mRNA chain to the end.
36 How Cells Make Proteins Protein Chain3D ProteinDNAmRNATranscriptionTranslationFoldinga.a. activation