1. 1 The Chemical Building Blocks of Life Chapter 3

2. 2 Outline Biological Molecules – Macromolecules  Proteins  Structure and Denaturation  Nucleic Acids  DNA and RNA  Lipids  Fats and Phospholipids  Carbohydrates  Transport and Storage

3. 3 Biological Molecules The framework of biological molecules consists of carbon bonded to other carbon molecules, or other types of atoms. – Hydrocarbons consist of carbon and hydrogen.  Covalent bonds store considerable energy.

4. 4 Biological Molecules Functional groups – specific groups of atoms attached to carbon backbones  retain definite chemical properties Macromolecules. – proteins – nucleic acids – lipids – carbohydrates

5. 5 Macromolecules Macromolecules are often polymers. – long molecule built by linking together small, similar subunits  Dehydration synthesis removes OH and H during synthesis of a new molecule.  Hydrolysis breaks a covalent bond by adding OH and H.

6. 6 Carbohydrates Carbohydrates are loosely defined as molecules that contain carbon, hydrogen, and oxygen in a 1:2:1 ratio. – monosaccharides - simple sugars – disaccharides - two monosaccharides joined by a covalent bond – polysaccharides - macromolecules made of monosaccharide subunits  isomers - alternative forms of the same substance

7. 7 H H H HH OH O H O HO O OH H H H HO H H H H OH H H H HO CH 2 OH H H H OH O Galactose Fructose Glucose RiboseGlyceraldehyde 3-carbon sugar 5-carbon sugars 6-carbon sugars Deoxyribose HH H H H H OH O C C C 4 5 1 3 2 4 4 4 4 5 5 5 5 6 6 6 1 1 1 1 3 3 2 2 3 3 2 2 1 3 2 CH 2 OH H Sucrose OH HO O OH O O Lactose OH HO H H H H H H H H H H H H H OH O H H O H H O Galactose Glucose Fructose Maltose CH 2 OH HO OHH HH H H H H H H H O O O CH 2 OH CO HCOH HC H HOC H CO HCOH H Fructose HCOH HC H C H HO C H H C OH H GlucoseGalactose Structural isomer Stereo- isomer HC C O HO C H H C OH H C H HOC H H COH H

8. 8 Carbohydrate Transport and Storage Transport disaccharides – Humans transport glucose as a simple monosaccharide. – Plants transform glucose into a disaccharide transport form. Storage polysaccharides – plant polysaccharides formed from glucose - starches  most is amylopectin

9. 9 Structural Carbohydrates Cellulose - plants – alpha form or beta form of ring Chitin - arthropods and fungi – modified form of cellulose

10. 10 Amino Acids Contain an amino group (-NH 2 ), a carboxyl group (- COOH) and a hydrogen atom, all bonded to a central carbon atom – twenty common amino acids grouped into five classes based on side groups  nonpolar amino acids  polar uncharged amino acids  charged amino acids  aromatic amino acids  special-function amino acids

11. 11 Proline (Pro) CH C NH 2 + O Methionine (Met) CH 2 CCO–O– HO S CH 3 Cysteine (Cys) H3N+H3N+ CCO–O– HO SH SPECIAL FUNCTION CH 2 H3N+H3N+ O–O–

12. 12 Amino Acids Peptide bond links two amino acids. – A protein is composed of one or more long chains of amino acids linked by peptide bonds (polypeptides).

13. 13 Proteins Protein functions: – enzyme catalysis – defense – transport – support – motion – regulation – storage

14. 14 Protein Structure Protein function is determined by its shape. – Protein structure  primary - specific amino acid sequence  secondary - folding of amino acid chains  motifs - folds or creases  supersecondary structure

15. 15 Protein Structure – tertiary - final folded shape of globular protein-determines protein activity and function – domains - functional units – quaternary - forms when two or more polypeptide chains associate to form a functional protein

16. 16 CH 2 CH 3 C C C O O N R R R C N C C C H C H H C CS C O O N N C H H C CS H H C C O O N N C C Hydrogen bond Disulfide bridge Van der Waals attraction Hydrophobic exclusion C C C C C O (CH 2 ) 4 (NH 3 +) CH 2 O O N 3 4 5 1 2 Ionic bond O–O– CH 3 N Interactions that contribute to protein’s shape

17. 17 Chaperone Proteins Chaperone proteins are special proteins which help new proteins fold correctly. – Chaperone deficiencies may play a role in facilitating certain diseases.

18. 18 Unfolding Proteins Denaturation refers to the process of changing a protein’s shape. – usually rendered biologically inactive  salt-curing and pickling used to preserve food

19. 19 Nucleic Acids Deoxyribonucleic Acid (DNA) – Encodes information used to assemble proteins. Ribonucleic Acid (RNA) – Reads DNA-encoded information to direct protein synthesis.

20. 20 Nucleic Acid Structure Nucleic acids are composed of long polymers of repeating subunits, nucleotides. – five-carbon sugar – phosphate – nitrogenous base  purines  adenine and guanine  pyrimidines  cytosine, thymine, and uracil Phosphate group Sugar Nitrogenous base N N O 4’4’ 5’5’ 1’1’ 3’3’2’2’ 2 8 7 6 3 9 4 5 PCH 2 O –O–O O–O– OHR OH in RNA H in DNA O N NH 2 N 1

21. 21 The nitrogenous bases Adenine Guanine C C N N N C H N C CH O H Cytosine (both DNA and RNA) Thymine (DNA only) Uracil (RNA only) HCC N C H N C NH 2 N N CH O C C N C H N C H H OC C N C H N C O H H3CH3C H O CC N C H N C O H H H PURINESPURINES PYRIMIDINESPYRIMIDINES

22. 22 Nucleic Acid Structure DNA exists as double- stranded molecules. – double helix – complementary base pairing  hydrogen bonding RNA exists as a single stand. – contains ribose instead of deoxyribose – contains uracil in place of thymine 5’5’ 3’3’ P P P P OH 5-carbon sugar Nitrogenous base Phosphate group O O O O Phosphodiester bonds

23. 23 Lipids Lipids are loosely defined as groups of molecules that are insoluble in water. – fats and oils Phospholipids form the core of all biological membranes. – composed of three subunits  glycerol  fatty acid  phosphate group SchematicFormulaSpace-filling modelIcon Polar hydrophilic heads Nonpolar hydro- phobic tails CH 2 C OO O O O P O O O–O– H2CH2C C H C CH 3 Choline Phosphate Glycerol FattyacidFattyacid FattyacidFattyacid CH 2 CH 3 CH 2 CH CH 2 N + (CH 3 ) 3 CH 2

24. 24 Fats and Other Lipids Fats consist a of glycerol molecule with three attached fatty acids (triglyceride / triglycerol). – Saturated fats - all internal carbon atoms are bonded to at least two hydrogen atoms – Unsaturated fats - at least one double bond between successive carbon atoms  Polyunsaturated - contains more than one double bond  usually liquid at room temperature

25. 25 To make a triglyceride

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27. 27 Fats as Energy Storage Molecules Fats, on average, yield about 9 kcal per gram versus 4 kcal per gram for carbohydrates. – Animal fats are saturated while most plant fats are unsaturated.  Consumption of excess carbohydrates leads to conversion into starch, glycogen, or fats for future use.

28. 28 Summary Biological Molecules – Macromolecules  Carbohydrates  Transport and Storage  Proteins  Structure and Denaturation  Nucleic Acids  DNA and RNA  Lipids  Fats and Phospholipids

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