Biology Sylvia S. Mader Michael Windelspecht Chapter 3 The Chemistry of Organic Molecules Part 2 Mills Biology 2012 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1

Lipids Phospholipids Important in animal cell walls Water soluble because of hydrophillic phosphate group Molecule has a hydrophillic and a hydrophobic end Amphipathic – has both polar and nonpolar regions Mills Biology 2012

Lipids Phospholipids Mills Biology 2012

Fig. 3.11 Phospholipids Form Membranes outside cell inside cell Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig. 3.11 Phospholipids Form Membranes glycerol O CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 Polar Head CH2 CH2 CH2 CH3 1 CH2 C O fatty acids 2 O CH2 O R O P O 3 CH2 C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH CH O CH2 Nonpolar Tails CH2 phosphate CH2 CH2 a. Phospholipid structure CH2 CH2 CH2 CH3 inside cell outside cell Mills Biology 2012 b. Plasma membrane of a cell .

Lipids Steroids Have a different structure than other lipids Backbone is made of four carbon rings Cholesterol, vit D, and many hormones (testosterone, estrogen) Mills Biology 2012

© Ernest A. Janes/Bruce Coleman/Photoshot Steroid Diversity Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. OH CH3 CH3 O b . T e s t o s t e r o n e CH3 HC CH3 (CH2)3 OH HC CH3 CH3 CH3 CH3 HO HO c. Estrogen a. Cholesterol © Ernest A. Janes/Bruce Coleman/Photoshot Mills Biology 2012

3.4 Proteins Proteins perform many functions Support Enzymes/Metabolism Transport Defense Hormones/Regulation Motion Mills Biology 2012

Proteins Contain C,H,O,N +\- S and P Structural, hormones, enzymes, receptors, antibodies Made up of amino acids (20 different amino acids) Amino acids joined by peptide bonds Length can vary from 100 a.a. to thousands Have primary, secondary and tertiary shape (structure) Denaturing can change structure back to primary Mills Biology 2012

Proteins show great variety Some structural proteins: hair, horn and spider web silk. Mills Biology 2012

How many different proteins could be formed from 20 amino acids? Proteins – amino acids COOH = carboxyl group How many different proteins could be formed from 20 amino acids? Mills Biology 2012

Proteins – peptide bond Dipeptide vs polypeptide? What is the name of this synthesis process? Mills Biology 2012

Insulin is composed of an A chain of 21 amino acids and a B chain of 30 amino acids, the chains being held together by two disulfide bonds. A third disulfide bond is present within the A chain. Insulin is an anabolic signal. The binding of the hormone to its receptor initiates a series of events within the cells that results in the increased uptake of glucose into the cells, where it is converted into metabolic energy or stored as glycogen and fat. http://www.chem.uwec.edu/Chem406/Webpages/Ying/overview.htm What was the first protein to have it’s primary structure mapped? How long did it take? The hormone, insulin, in 1953. It took Frederick Sanger(won Nobel Prize in Chemistry in 1958 AND 1980) 10 years to determine the sequence! Proteins – structure                                             Thank You Fred! Mills Biology 2012

Proteins – Structure Primary – order of a.a. Secondary – 3 dimensional shape that results from H bonds Alpha helix Pleats Tertiary structure – 3 dimensional shape Globular proteins H bonding Hydrophobic effect Ionic bonding Disulfide bonds Quaternary structure – made of 2 or more peptide chains Example – hemoglobin made from 4 globular proteins Mills Biology 2012

Copyright © The McGraw-Hill Companies, Inc Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H3N+ Primary Structure This level of structure is determined by the sequence of amino acids coded by a gene that joins to form a polypeptide. amino acid peptide bond COO– C O CH C hydrogen bond O C N O CH R C C C N H N C CH R hydrogen bond R H O H O C C O C H R R C C N O C O H R H N C CH H N N C N H C C CH R C O O O R O H C C N N H R R O C N H R H N H C Secondary Structure O C O R CH C C O C N R Hydrogen bonding between amino acids causes the polypeptide to form an alpha helix or a pleated sheet. CH R C C N C O N H H R N N C R CH C C O O H N α alpha) helix Β (beta) sheet = pleated sheet Tertiary Structure Interactions of amino acid side chains with water, covalent bonding between R groups, and other chemical interactions determine the folded three-dimensional shape of a protein. disulfide bond Quaternary Structure This level of structure occurs when two or more folded polypeptides interact to perform a biological function.

Protein-Folding Diseases Biology, 9th ed,Sylvia Mader Chapter 03 Slide #15 Protein-Folding Diseases Organic Chemistry Chaperone proteins help proteins fold into their normal shape. Defects in chaperone proteins may play a role in several human diseases such as Alzheimer disease and cystic fibrosis. Prions are misfolded proteins that have been implicated in a group of fatal brain diseases known as TSEs. Mad cow disease is one example of a TSE disease. 15

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Proteins – Structure - denaturing When get perm-breaks disulfide bonds and then makes new ones that are not aligned. The amino acid cysteine has an “R” group that ends with a sulfhydryl (-SH). Often form disulfa bonds between amino acid chains. Mills Biology 2012

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Proteins – simple mistake-big problem Glutamic acid and Valine are amino acids. Can you identify the disease? Sickle Cell Disease Mills Biology 2012 For more info: http://sickle.bwh.harvard.edu/scd_background.html

Sample Amino Acids with Nonpolar (Hydrophobic) R Groups Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sample Amino Acids with Nonpolar (Hydrophobic) R Groups H O H H O O H H3N+ O C C H3N+ C C H3N+ C C H O O O H3N+ O CH2 H2N+ C C (CH2)2 CH2 C C O O CH CH S H2C CH2 CH3 CH3 CH3 H3C CH2 CH3 valine (Val) methionine (Met) phenylalanine (Phe) leucine (Leu) proline (Pro) Sample Amino Acids with Polar (Hydrophilic) R Groups H O H O H O H O H3N+ C C H3N+ C C H3N+ C C H3N+ C C O O CH2 O O CH CH2 (CH2)2 SH OH C cysteine (Cys) serine (Ser) H O NH2 O OH glutamine (Gln) H3N+ C C H O tyrosine (Tyr) O H3N+ C C CH2 O CH C NH2 O OH CH3 asparagine (Asn) threonine (Thr) Sample Amino Acids with Ionized R Groups H O H O H O H3N+ C C H3N+ C C H H O O O H3N+ C C CH2 (CH2)3 O H3N+ C C H3N+ C C O O CH2 CH2 O CH2 NH CH2 NH CH2 CH2 C C N+H2 COO- N+H3 O O NH2 N+H glutamicacid (Glu) lysine (Lys) aspartic acid (Asp) arginine (Arg) histidine (His)