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Engineering Proteins EP2 Protein Synthesis. Amino Acids.

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Presentation on theme: "Engineering Proteins EP2 Protein Synthesis. Amino Acids."— Presentation transcript:

1 Engineering Proteins EP2 Protein Synthesis

2 Amino Acids

3 Some of the 20 Naturally Occurring Amino Acids

4 Amino Acids - Summary Zwitterions Acid / Base Chemistry (Buffers) Optical Isomerism – chiral centre, CORN Peptide – Secondary Amides Naming dipeptides – NH 2 on left Hydrolysis of peptides Condensation to form polypeptides and proteins

5 Dipeptides

6 Condensation

7 Protein Structure 4 levels of structure:- oPrimary Structure – Sequence of Amino Acids ; oSecondary Structure – Spatial arrangement of sections of primary Structure (e.g. helices); oTertiary Structure – Overall 3D Shape of protein ; oQuaternary Structure – Protein “Monomers” coordinated into tetramers (haemoglobin), or hexamers (insulin).

8 Primary Structure

9 Secondary Structure  - Helix  - Sheet

10 Tertiary Structure – gyrase

11 Quaternary Structure – Insulin Hexamer

12 Insulin Hexamer

13 Building Proteins Cells build proteins directly from L-Amino Acids. To synthesise a protein, a Chemist would need:- 1)Instructions / knowledge of the primary structure; 2)Supplies of pure amino acids; 3)A method of forming peptide links. Cells adopt a similar approach – Protein Synthesis.

14 Protein synthesis – The role of RNA 1)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.

15 1) Messenger RNA (mRNA)

16 2) Transfer RNA (tRNA)

17 3) Ribosomal RNA (rRNA)

18 What is RNA? – ribonucleic acid

19 Nucleic Acids

20 mRNA triplet base codes (ppt)(ppt)

21 RNA Base Pairs

22 A Permanent set of Instructions DNA

23 DNA – deoxyribonucleic acid 1)Codes for many mRNA molecules. 2)The section of DNA coding for a particular protein is called a gene. 3)Full set of genes = genome (humans 3.5 x 10 9 bases)

24 Differences between RNA and DNA

25 DNA Base Pairs

26 DNA


28 How Cells Make Proteins DNAmRNA Transcription


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 DNAmRNA Protein Chain TranscriptionTranslation a.a. activation

32 Amino Acid Activation

33 1.tRNA molecule forms an ester link with a specific amino acid; 2.tRNA – amino acid complex moves to the Ribosome.

34 Translation (ppt)(ppt)

35 Translation - in the cytoplasm 1)mRNA attaches to ribosome; 2)Hydrogen bonding between complementary bases binds the correct tRNA anticodon to the 1 st codon (set of 3 bases on mRNA); 3)A 2 nd tRNA – amino acid complex binds to the adjacent mRNA codon in the ribosome; 4)Ribosome catalyses the formation of the peptide bond between amino acids; 5)The tRNA is released once the amino acid is delivered; 6)Ribosome moves along the mRNA chain to the end.

36 How Cells Make Proteins DNAmRNA Protein Chain 3D Protein TranscriptionTranslation a.a. activation Folding

37 Protein Synthesis

38 How Cells Make Proteins DNAmRNA Protein Chain 3D Protein TranscriptionTranslation a.a. activation Folding

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