1. End Show © Copyright Pearson Prentice Hall Slide 1 of 31 24.3 Amino Acids & Proteins – What are they and what do we need them for? Amino acids are the monomers for proteins.  Made of C, H, O, N and sometimes S  Nearly your whole outside (1/2 dry body wt). Hair, eyeballs, skin, nails. Collagen, hemoglobin, myoglobin. All enzymes are made of protein. Homeostasis (keep constant pH, T, gas/ion flow, metabolism, contract muscles…)

2. End Show Slide 2 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Amino Acids What do amino acids look like? Contain both an amino group (—NH 2 ) and a carboxylic acid group (—COOH) So, what is R?

3. End Show Slide 3 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > The Twenty amino acids Which side chains contain…? S? -OH? aromatic? Chiral? All same type exist on Earth! Curly hair?

4. End Show Slide 4 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Amino Acids Mostly all species on the planet use the same 20 a.a. No vertebrate can make all 20. Humans can synthesize 11, so then 9 a.a are essential to us. Your body cannot store protein! E. coli can!

5. End Show Slide 5 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Peptides A peptide bond is formed when a.a’s join together. How does this work? What type of reaction is this? Condensation! Polypeptide = many a.a linked together. 5000 – several million g/mol!!! Proteios = Greek for “first” dipeptide

6. End Show Slide 6 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Proteins a.a in a peptide chain (primary structure of a protein) If only 2 a.a. long, then 2 20 combos!! Linkage order is important: phe-asp or asp-phe ?? Nutrasweet – let’s draw it!

7. End Show Slide 7 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Proteins Secondary structure – folding of 1  Alpha helix (disc. by Linus Pauling late 1930’s) Beta sheet ( silk ) Hmmm…how do they stay folded?

8. End Show Slide 8 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Which is Which??? Alpha helix Beta sheet http://www.youtube.com/watch?v=wM2LWCTWlrE

9. End Show Slide 9 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Is there a tertiary structure? YES! (Folding & bending of 2  ) http://www.youtube.com/watch?v=lijQ3a8yUYQ There sometimes is quaternary structure too! (joining of polypeptides) Leads to specificity of protein! What holds them together?

10. End Show © Copyright Pearson Prentice Hall Amino Acids and Their Polymers > Slide 10 of 31 24.3 Proteins

11. End Show Slide 11 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Pretty quaternary structures

12. End Show Slide 12 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Proteins The Shape of Hemoglobin 574 a.a in length The Shape of Collagen

13. End Show Slide 13 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Proteins are fragile due to weak IMFs holding 2, 3, 4  together. Can be denatured. http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter2/animation__protein_denaturation.html http://www.youtube.com/watch?v=o2ju5ys3Cxc How? heat, pH changes, chemicals Ex: Grilling burgers, scrambling eggs, making cheese/tofu (“coagulated protein food products”)

14. END OF SHOW