1. 1 3.1 Organic Molecules Organic molecules contain carbon and hydrogen atoms. Four classes of organic molecules (biomolecules) exist in living organisms:  Carbohydrates  Lipids  Proteins  Nucleic Acids

2. 2 The Carbon Skeleton and Functional Groups The carbon chain of an organic molecule is called its skeleton or backbone. Functional groups are clusters of specific atoms bonded to the carbon skeleton with characteristic structures and functions.  Determine the chemical reactivity and polarity of organic molecules

3. Table 3.2

4. 4 Biomolecules Carbohydrates, lipids, proteins, and nucleic acids are called biomolecules.  Usually consist of many repeating units Each repeating unit is called a monomer. A molecule composed of monomers is called a polymer (many parts). –Example: amino acids (monomer) are joined together to form a protein (polymer)

5. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig. 3.3 Biomolecules PolymerCategory Subunit(s) PolysaccharideCarbohydrates*Monosaccharide Lipids Proteins* Nucleic acids* Glycerol and fatty acidsFat Polypeptide Amino acids NucleotideDNA,RNA *Polymers © The McGraw Hill Companies, Inc./John Thoeming, photographer

6. 6 Synthesis and Degradation A dehydration reaction is a chemical reaction in which subunits are joined together by the formation of a covalent bond and water is produced during the reaction.  Used to connect monomers together to make polymers  Example: formation of starch (polymer) from glucose subunits (monomer) A hydrolysis reaction is a chemical reaction in which a water molecule is added to break a covalent bond.  Used to breakdown polymers into monomers  Example: digestion of starch into glucose monomers

7. monomer Dehydration reaction H2OH2O OHH a. Synthesis of a biomolecule Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. +

8. monomer Hydrolysis reaction OHH b. Degradation of a biomolecule H2OH2O monomer Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

9. monomer dehydration reaction monomer H 2 O OHH H b. Degradation of a biomolecule a. Synthesis of a biomolecule H 2 O monomer hydration reaction Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

10. 10 Synthesis and Degradation Enzymes are required for cells to carry out dehydration synthesis and hydrolysis reactions.  An enzyme is a molecule that speeds up a chemical reaction. Enzymes are not consumed in the reaction. Enzymes are not changed by the reaction.

11. 3.2 Carbohydrates Functions:  Energy source  Provide building material (structural role) Contain carbon, hydrogen and oxygen in a 1:2:1 ratio Varieties: monosaccharides, disaccharides, and polysaccharides

12. 12 A monosaccharide is a single sugar molecule. Also called simple sugars Have a backbone of 3 to 7 carbon atoms Examples:  Glucose (blood), fructose (fruit) and galactose Hexoses - six carbon atoms  Ribose and deoxyribose (in nucleotides) Pentoses – five carbon atoms Monosaccharides

13. 13 Disaccharides A disaccharide contains two monosaccharides joined together by dehydration synthesis. Examples:  Lactose (milk sugar) is composed of galactose and glucose.  Sucrose (table sugar) is composed of glucose and fructose.  Maltose is composed of two glucose molecules.

14. Figure 5.5 Examples of disaccharide synthesis

15. Polysaccharides Storage: Starch~ glucose monomers Plants: plastids Animals: glycogen Polysaccharides Structural: Cellulose~ most abundant organic compound; Chitin~exoskeletons; cell walls of fungi; surgical thread

16. Lipids 3.3 No polymers; glycerol and fatty acid Fats, phospholipids, steroids Hydrophobic; H bonds in water exclude fats Carboxyl group = fatty acid Non-polar C-H bonds in fatty acid ‘tails’ Ester linkage: 3 fatty acids to 1 glycerol (dehydration formation) Triacyglycerol (triglyceride) Saturated vs. unsaturated fats; single vs. double bonds

18. Triglycerides: Long-Term Energy Storage  Also called fats and oils  Functions: long-term energy storage and insulation  Consist of one glycerol molecule linked to three fatty acids by dehydration synthesis

19. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. in 3 H 2 O + CH H CH C H H C O C O C O H H HH CCCCC HHHHH H H H HHH HHHHHHH CC HH H HH HHHHH CCCCC C C CCC H HH H H HHHHH HCCCCC HHHHH HHHHHHH CCCCCCC HHHHHH H H HHH H C C CCC H HH in OH HO H H H H C C C O H O C O O C H O C fat molecule 3 water molecules 3 fatty acidsglycerol a.Formation of a fat

20. 20 Fatty acids are either unsaturated or saturated.  Unsaturated - one or more double bonds between carbons Tend to be liquid at room temperature –Example: plant oils  Saturated - no double bonds between carbons Tend to be solid at room temperature –Examples: butter, lard Triglycerides: Long-Term Energy Storage

21. 21 Composed of four fused carbon rings  Various functional groups attached to the carbon skeleton Functions: component of animal cell membrane, regulation Examples: cholesterol, testosterone, estrogen Cholesterol is the precursor molecule for several other steroids. Steroids: Four Fused Carbon Rings

22. 22 3.4 Proteins Proteins are polymers of amino acids linked together by peptide bonds.  A peptide bond is a covalent bond between amino acids. Two or more amino acids joined together are called peptides.  Long chains of amino acids joined together are called polypeptides. A protein is a polypeptide that has folded into a particular shape and has function.

23. 23 Functions of Proteins Metabolism  Most enzymes are proteins that act as catalysts to accelerate chemical reactions within cells. Support  Keratin and collagen Transport  Hemoglobin and membrane proteins Defense  Antibodies Regulation  Hormones are regulatory proteins that influence the metabolism of cells. Motion  Muscle proteins and microtubules

24. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. C H R acidic group amino group COOH H2NH2N R = rest of molecule Amino Acids: Protein Monomers There are 20 different common amino acids. Amino acids differ by their R groups.

25. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H Sample Amino Acids with Nonpolar (Hydrophobic) R Groups CC H O O C H C O O C H C O O CC H O O S C C O O C C H O O C O C C H O O C C H O O C O C C H O O C O O CC H O O C C C H O O C H C O O C H C O O C H C O O C C H O O CC O O CH 2 H3N+H3N+ H3CH3C CH 3 H3N+H3N+ (CH 2 ) 2 CH 3 H3N+H3N+ CH 2 H3N+H3N+ H3N+H3N+ SH OH CH H3N+H3N+ H3N+H3N+ H3N+H3N+ CH 2 (CH 2 ) 2 H3N+H3N+ CH 2 N+H3N+H3 OH H3N+H3N+ CH 3 NH 2 H3N+H3N+ H3N+H3N+ CH 2 COO - H3N+H3N+ CH 2 H3N+H3N+ (CH 2 ) 3 NH N+H2N+H2 NH 2 H3N+H3N+ CH 2 NH N+HN+H histidine (His)arginine (Arg)aspartic acid (Asp) lysine (Lys)glutamicacid (Glu) asparagine (Asn)threonine (Thr) Sample Amino Acids with Polar (Hydrophilic) R Groups proline (Pro)leucine (Leu)phenylalanine (Phe)methionine (Met)valine (Val) CH CH 3 CH 2 CH CH 2 H2N+H2N+ H2CH2C glutamine (Gln) cysteine (Cys)serine (Ser) tyrosine (Tyr) OH CH Sample Amino Acids with Ionized R Groups CH 3 NH 2 H CH 2

26. amino acid amino group Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Synthesis and Degradation of a Peptide

27. dehydration reaction hydrolysis reaction water peptide bond dipeptide amino acid acidic groupamino group Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

28. 28 Levels of Protein Structure Proteins cannot function properly unless they fold into their proper shape.  When a protein loses it proper shape, it said to be denatured. Exposure of proteins to certain chemicals, a change in pH, or high temperature can disrupt protein structure. Proteins can have up to four levels of structure:  Primary  Secondary  Tertiary  Quaternary

29. 29 Four Levels of Protein Structure  Primary The sequence of amino acids  Secondary Characterized by the presence of alpha helices and beta (pleated) sheets held in place with hydrogen bonds  Tertiary Final overall three-dimensional shape of a polypeptide Stabilized by the presence of hydrophobic interactions, hydrogen bonding, ionic bonding, and covalent bonding  Quaternary Consists of more than one polypeptide

30. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. COO – hydrogen bond Primary Structure This level of structure is determined by the sequence of amino acids coded by a gene that joins to form a polypeptide. Secondary Structure Hydrogen bonding between amino acids causes the polypeptide to form an alpha helix or a pleated sheet. Β (beta) sheet = pleated sheet α alpha) helix C N R C R C N C R C N C R N C R N R N C N R CH Tertiary Structure disulfide bond Quaternary Structure This level of structure occurs when two or more folded polypeptides interact to perform a biological function. hydrogen bond 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. peptide bond amino acid H 3 N+ C C C C C C C C C C C C C C C C C C C C C C R R R R R R R R R O O O O O O O O O O O O N N N N N N N N N N N C H H H H H H H H H H C O O O O O O O H H H H H H

31. 31 3.5 Nucleic Acids Nucleic acids are polymers of nucleotides. Two varieties of nucleic acids:  DNA (deoxyribonucleic acid) Genetic material that stores information for its own replication and for the sequence of amino acids in proteins.  RNA (ribonucleic acid) Perform a wide range of functions within cells which include protein synthesis and regulation of gene expression

32. 32 Structure of a Nucleotide Each nucleotide is composed of three parts:  A phosphate group  A pentose sugar  A nitrogen-containing (nitrogenous) base There are five types of nucleotides found in nucleic acids.  DNA contains adenine, guanine, cytosine, and thymine.  RNA contains adenine, guanine, cytosine, and uracil. Nucleotides are joined together by a series of dehydration synthesis reactions to form a linear molecule called a strand.

33. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. S C O P nitrogen- containing base pentose sugar 5' 4' 1' 2' 3' phosphate Nucleotides

34. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. S C O –O P O O O–O– H O C C C C H H H H O C C CC H H H H O N N H O N C C C C C C CC H O N H N N N N H N N N C C C H CTU GA P nitrogen- containing base phosphate pentose sugarribose (in RNA)deoxyribose (in DNA) Nucleotide structurea. PurinesPyrimidines OH HN CH HC CH HN CH guanineadenineuracil in RNA Pyrimidines versus purinesc. cytosinethymine in DNA CH 2 OH NH 2 HN CH 3 NH 2 H2NH2N OO O 5' 4' 1' 2' 3' b. Deoxyribose versus ribose

35. 35 Structure of DNA and RNA  The backbone of the nucleic acid strand is composed of alternating sugar-phosphate molecules.  RNA is predominately a single-stranded molecule.  DNA is a double-stranded molecule. DNA is composed of two strands held together by hydrogen bonds between the nitrogen-containing bases. The two strands twist around each other to form a double helix. –Adenine hydrogen bonds with thymine –Cytosine hydrogen bonds with guanine The bonding between the nucleotides in DNA is referred to as complementary base pairing.

36. 36 A Special Nucleotide: ATP ATP (adenosine triphosphate) is composed of adenine, ribose, and three phosphates. ATP is a high-energy molecule due to the presence of the last two unstable phosphate bonds. Hydrolysis of the terminal phosphate bond yields:  The molecule ADP (adenosine diphosphate)  An inorganic phosphate  Energy to do cellular work ATP is called the energy currency of the cell.

37. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ATP N N N N + + P PP P P P N N N N ENERGY phosphatediphosphate ADP triphosphate ATPb. NH 2 H2OH2O adenosinetriphosphatec.a. adenosine c: © Jennifer Loomis / Animals Animals / Earth Scenes