2. Lipids A. Classified based on solubility (like dissolves like) 1. insoluble in polar solvents 2. soluble in nonpolar solvents 3. lipids are hydrophobic

3. B. Triglycerides (fats and oils) 1. contain fatty acids a. -COOH functional group at end of a carbon chain b. always have an even number of carbons c. can be saturated (with H) d. can be unsaturated have C=C double bonds polyunsaturated

4. B. Triglycerides (cont.) 2. contain glycerol a. is a 3-carbon alcohol b. has 3 -OH functional groups

5. C. Triglyceride synthesis 1. -COOH groups react with -OH groups form covalent bonds

6. 2. fats:solid at room temperature 3. oils:liquid at room temperature usually saturated mostly unsaturated from plants

7. 4. the greater the unsaturation, the lower the melting point (more likely to be liquid at room temp.)

8. D. Phospholipids 1. one fatty acid replaced with a -PO 4 functional group 2. has both hydrophobic and hydrophilic portions (amphiphilic/amphipathic)

9. E. Steroids 1. all have basic 4 carbon ring structure 2. differences are in functional groups and their locations 3. cholesterol is the precursor for animal steroids

10. Protein A. Polymer of amino acids 1. 20 naturally occurring amino acids - eight of these are “essential” in humans

11. 2. three components a. amino group b. carboxyl group c. R group accounts for the 20 different amino acids

13. B. Amino acids are linked together by peptide bonds. Polymers > 100 amino acids long may be considered proteins

14. C. Size glucose =C 6 H 12 O 6 hemoglobin =C 2952 H 4664 O 832 N 812 S 8 Fe 4

15. Figure 3.14A–D Protein structure (layer 1) Levels of Protein Structure Gly Thr Gly Glu SerLys Cys Pro LeuMet Val Lys Val Leu Asp Ala Val Arg Gly Ser Pro Ala Ile Asn Val Ala Val His Val Amino acids Phe Arg

16. Figure 3.14A–D Protein structure (layer 2)

17. Figure 3.14A–D Protein structure (layer 3) most tertiary structures are either globular or fibrous

18. Figure 3.14A–D Protein structure (layer 4) Levels of Protein Structure Gly Thr Gly Glu SerLys Cys Pro LeuMet Val Lys Val Leu Asp Ala Val Arg Gly Ser Pro Ala Ile Asn Val Ala Val His Val C N O C C N H O C C H Hydrogen bond O C N H C C O N H O C C N H C N O C C N H O C C N H C O C H N H C O H C R H N Alpha helix Amino acids C N H C C H H O N R C C O N H O C C N H C C O N H O C C N H C O C N H O C C N H C O O C C N H C C O N H C C O N H C C O N H C C O N H C C O N H C C O N H C C O H N C Pleated sheet Polypeptide (single subunit of transthyretin) Transthyretin, with four identical polypeptide subunits Phe Arg

19. examples having quaternary structure: hemoglobin, collagen

20. Biological Functions of Proteins Enzymes Structural molecules Regulatory molecules Transport Protection Movement Also: (globular) (fibrous)

21. A given type of protein will have a unique amino acid sequence. A protein typically has only a single function in nature.

22. Shape of a protein determines which molecules can bind to it. The 3-D shape of a protein determines its function. Change shape  Change function

24. Protein Denaturation Unfolding of proteins due to chemicals, changes in pH and/or increased temperature

25. Protein Denaturation Irreversibly denatured proteins cannot refold and are formed by extreme pH or temperature changes

26. Hydrolysis “Breakdown” to individual amino acids Breakage of peptide bonds Gly Thr Gly Glu SerLys Cys Pro LeuMet Val Lys Val Leu Asp Ala Val Arg Gly Ser Pro Ala Ile Asn Val Ala Val His Val Phe Arg