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Engineering Proteins EP2 Protein Synthesis
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Amino Acids
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Some of the 20 Naturally Occurring Amino Acids
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Amino Acids - Summary Zwitterions Acid / Base Chemistry (Buffers)
Optical Isomerism – chiral centre, CORN Peptide – Secondary Amides Naming dipeptides – NH2 on left Hydrolysis of peptides Condensation to form polypeptides and proteins
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Dipeptides
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Condensation
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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).
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Primary Structure
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Secondary Structure - Helix - Sheet
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Tertiary Structure – gyrase
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Quaternary Structure – Insulin Hexamer
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Insulin Hexamer
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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.
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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.
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1) Messenger RNA (mRNA)
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2) Transfer RNA (tRNA)
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3) Ribosomal RNA (rRNA)
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What is RNA? – ribonucleic acid
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Nucleic Acids
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mRNA triplet base codes (ppt)
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RNA Base Pairs
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A Permanent set of Instructions
DNA
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DNA – deoxyribonucleic acid
Codes for many mRNA molecules. The section of DNA coding for a particular protein is called a gene. Full set of genes = genome (humans 3.5 x 109 bases)
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Differences between RNA and DNA
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DNA Base Pairs
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DNA
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DNA
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How Cells Make Proteins
DNA mRNA Transcription
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Transcription
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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.
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How Cells Make Proteins
Protein Chain DNA mRNA Transcription Translation a.a. activation
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Amino Acid Activation
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Amino Acid Activation tRNA molecule forms an ester link with a specific amino acid; tRNA – amino acid complex moves to the Ribosome.
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Translation (ppt)
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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.
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How Cells Make Proteins
Protein Chain 3D Protein DNA mRNA Transcription Translation Folding a.a. activation
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Protein Synthesis
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How Cells Make Proteins
Protein Chain 3D Protein DNA mRNA Transcription Translation Folding a.a. activation
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