1 Organic Chemistry The Structure and Function of Macromolecules

Organic compounds contain carbon and are associated with living things. Carbon is so vital to life, an entire branch of chemistry is devoted to its study: organic chemistry Carbon!

Characteristics of Carbon!

4 The Molecules of Life Overview: –Another level in the hierarchy of biological organization is reached when small organic molecules are joined together –Atom  molecule  macromolecule

Macromolecules Large molecules are called macromolecules The macromolecules are composed of submits called MONOMERS. A POLYMER is composed of many monomers.

Building Polymers Why it is called Dehydration

7 Macromolecules Most macromolecules are polymers, built from monomers Four classes of life’s organic molecules are polymers –Carbohydrates –Proteins –Nucleic acids –Lipids

CARBOHYDRATES LIPIDS PROTEINS NUCLEIC ACIDS 4 Classes of Biological Macromolecules

CARBOHYDRATES Monomer is monosaccharide Monosaccharides are the simple sugars They contain C, H and O in a 1:2:1 ratio and may be represented by the general formula CH 2 O

Complex Carbohydrates Two monosaccharides = a disaccharide More than two = polysaccharide

11 Complex Carbohydrates Serve as fuel (energy) and building material (cellular structure) Include both sugars and their polymers (starch, cellulose, glycogen, chitin)

Complex Carbohydrates Glycogen (animals) Starch (plants) are energy storing Cellulose is in plant cells Chitin is the major component in the exoskeleton of arthropods

Complex Carbohydrates Monosaccharides –May be linear –Can form rings 13 H H C OH HO C H H C OH H C O C H H OH 4C4C 6 CH 2 OH 5C5C H OH C H OH H 2 C 1C1C H O H OH 4C4C 5C5C 3 C H H OH OH H 2C2C 1 C OH H CH 2 OH H H OH HO H OH H OH 3 O H O O 6 1 Figure 5.4

Complex Carbohydrates Examples of monosaccharides 14 Triose sugars (C 3 H 6 O 3 ) Pentose sugars (C 5 H 10 O 5 ) Hexose sugars (C 6 H 12 O 6 ) H C OH HO C H H C OH HO C H H C OH C O H C OH HO C H H C OH C O H H H HHH H H HHH H H H C CCC O O O O Aldoses Glyceraldehyde Ribose Glucose Galactose Dihydroxyacetone Ribulose Ketoses Fructose Figure 5.3

Complex Carbohydrates Disaccharides –Consist of two monosaccharides –Are joined by a glycosidic linkage H HO H H OH H OH O H CH 2 OH H HO H H OH H OH O H CH 2 OH H O H H OH H OH O H CH 2 OH H H2OH2O H2OH2O H H O H HO H OH O H CH 2 OH HO OH H CH 2 OH H OH H H HO OH H CH 2 OH H OH H O O H OH H CH 2 OH H OH H O H OH CH 2 OH H HO O CH 2 OH H H OH O O – 4 glycosidic linkage 1–2 glycosidic linkage Glucose Fructose Maltose Sucrose OH H H

Storage Polysaccharides Starch –Is a polymer consisting entirely of glucose monomers –Is the major storage form of glucose in plants Glycogen –Consists of glucose monomers –Is the major storage form of glucose in animals Chloroplast Starch Amylose Amylopectin 1  m Starch: a plant polysaccharide Mitochondria Giycogen granules 0.5  m Glycogen: an animal polysaccharide Glycogen

17 Structural Polysaccharides Cellulose –Is a polymer of glucose –Has different glycosidic linkages than starch (c) Cellulose: 1– 4 linkage of  glucose monomers H O O CH 2 OH H OH H H H H HO 4 C C C C C C H H H OH H H O CH 2 OH H H H OH H H HO 4 OH CH 2 OH O OH HO 4 1 O CH 2 OH O OH O CH 2 OH O OH CH 2 OH O OH O O CH 2 OH O OH HO 4 O 1 OH O O CH 2 OH O OH O O (a)  and  glucose ring structures (b) Starch: 1– 4 linkage of  glucose monomers 1  glucose  glucose CH 2 OH Figure 5.7 A–C

18 Plant cells 0.5  m Cell walls Cellulose microfibrils in a plant cell wall  Microfibril CH 2 OH OH O O O CH 2 OH O O OH O CH 2 OH OH O O CH 2 OH O O OH CH 2 OH O O OH O O CH 2 OHOH CH 2 OHOH O O CH 2 OH OH O CH 2 OH O O OHCH 2 OH OH  Glucose monomer O O O O O O Parallel cellulose molecules are held together by hydrogen bonds between hydroxyl groups attached to carbon atoms 3 and 6. About 80 cellulose molecules associate to form a microfibril, the main architectural unit of the plant cell wall. A cellulose molecule is an unbranched  glucose polymer. OH O O Cellulose molecules Figure 5.8 –Cellulose is a major component of the tough walls that enclose plant cells

19 Cellulose is difficult to digest –Cows have microbes in their stomachs to facilitate this process Figure 5.9

20 Chitin, another important structural polysaccharide –Is found in the exoskeleton of arthropods –Can be used as surgical thread (a) The structure of the chitin monomer. O CH 2 O H OH H H H NH C CH 3 O H H (b) Chitin forms the exoskeleton of arthropods. This cicada is molting, shedding its old exoskeleton and emerging in adult form. (c) Chitin is used to make a strong and flexible surgical thread that decomposes after the wound or incision heals. OH Figure 5.10 A–C

21 Lipids Lipids are a diverse group of hydrophobic molecules –Are the one class of large biological molecules that do not consist of polymers –Share the common trait of being hydrophobic –fats and oils –waxes –sterols Monomer is the fatty acid Structure is mostly C and H

22 Fats –Are constructed from two types of smaller molecules, a single glycerol and usually three fatty acids –Vary in the length and number and locations of double bonds they contain

23 Saturated fatty acids –Have the maximum number of hydrogen atoms possible –Have no double bonds (a) Saturated fat and fatty acid Stearic acid Figure 5.12

24 Unsaturated fatty acids –Have one or more double bonds (b) Unsaturated fat and fatty acid cis double bond causes bending Oleic acid Figure 5.12

25 Phospholipids –Have only two fatty acids –Have a phosphate group instead of a third fatty acid

26 Phospholipid structure –Consists of a hydrophilic “head” and hydrophobic “tails”

27 The structure of phospholipids –Results in a bilayer arrangement found in cell membranes Hydrophilic head WATER Hydrophobic tail Figure 5.14

28 Lipids Function –Energy Storage –Fats store twice as many calories as carbohydrates –Protection of vital organs and insulation –Fat is stored in adipose cells.

Sterols Characterized by a carbon skeleton consisting of four fused rings Steroids- differ from other lipids in structure but are classified as a lipid because they are insoluble in water –Examples Cholesterol Progesterone Vitamin D

Proteins Many structures, resulting in a wide range of functions Amino acids are the building blocks of proteins. Needed for Structural support and movement(bone, cartilage, muscle) Storage/transport molecules (hemoglobin) Hormones (insulin-sugar breakdown) Enzymes (control of cellular reactions) Amino acids joined together by special covalent bonds called peptide bonds

Amino Acid -COOH, which is a carboxyl group (acidic). -NH2, which is an amino group (basic). -H hydrogen. -R which varies depending on the amino acid

Amino Acid All 20 different amino acids 10 essential - you must get them from food 10 non-essential – your body can make them The amino acids are the alphabet in which the proteins are written.

33 Enzymes –Are a type of protein that acts as a catalyst, speeding up chemical reactions Substrate (sucrose) Enzyme (sucrase) Glucose OH H O H2OH2O Fructose 3 Substrate is converted to products. 1 Active site is available for a molecule of substrate, the reactant on which the enzyme acts. Substrate binds to enzyme Products are released. Figure 5.16

34 Twenty Amino Acids 20 different amino acids make up proteins O O–O– H H3N+H3N+ C C O O–O– H CH 3 H3N+H3N+ C H C O O–O– C C O O–O– H H3N+H3N+ CH CH 3 CH 2 C H H3N+H3N+ CH 3 CH 2 CH C H H3N+H3N+ C CH 3 CH 2 C H3N+H3N+ H C O O–O– C H3N+H3N+ H C O O–O– NH H C O O–O– H3N+H3N+ C CH 2 H2CH2C H2NH2N C H C Nonpolar Glycine (Gly) Alanine (Ala) Valine (Val) Leucine (Leu) Isoleucine (Ile) Methionine (Met) Phenylalanine (Phe) C O O–O– Tryptophan (Trp) Proline (Pro) H3CH3C Figure 5.17 S O O–O–

35

36 Protein Conformation and Function Instrumental in nearly everything organisms do; 50% dry weight of cells The most structurally sophisticated molecules known A protein’s specific conformation (shape) determines how it functions

37 Four Levels of Protein Structure Primary structure –Is the unique sequence of amino acids in a polypeptide Figure 5.20 – Amino acid subunits + H 3 N Amino end o Carboxyl end o c Gly ProThr Gly Thr Gly Glu Seu Lys Cys Pro Leu Met Val Lys Val Leu Asp Ala Val Arg Gly Ser Pro Ala Gly lle Ser Pro Phe His Glu His Ala Glu Val Phe Thr Ala Asn Asp Ser Gly Pro Arg Tyr Thr lle Ala Leu Ser Pro Tyr Ser Tyr Ser Thr Ala Val Thr Asn Pro Lys Glu Thr Lys Ser Tyr Trp Lys Ala Leu Glu Lle Asp

38 O C  helix  pleated sheet Amino acid subunits N C H C O C N H C O H R C N H C O H C R N H H R C O R C H N H C O H N C O R C H N H H C R C O C O C N H H R C C O N H H C R C O N H R C H C O N H H C R C O N H R C H C O N H H C R C O N H H C R N H O O C N C R C H O C H R N H O C R C H N H O C H C R N H C C N R H O C H C R N H O C R C H H C R N H C O C N H R C H C O N H C Secondary structure –Is the folding or coiling of the polypeptide into a repeating configuration –Includes the  helix and the  pleated sheet H H Figure 5.20

39 Tertiary structure –Is the overall three-dimensional shape of a polypeptide –Results from interactions between amino acids and R groups CH 2 CH OHOH O C HO CH 2 NH 3 + C -O-O CH 2 O SS CH CH 3 H3CH3C H3CH3C Hydrophobic interactions and van der Waals interactions Polypeptide backbone Hyrdogen bond Ionic bond CH 2 Disulfide bridge

40 Quaternary structure –Is the overall protein structure that results from the aggregation of two or more polypeptide subunits

41 Review Structure of Proteins Primary Structure - the sequence of amino acids, which form a chain Secondary structure Alpha helix Beta-sheets Random coil Tertiary structure – folding of the coil Quaternary structure – two or more chains joined together

Types of Proteins NormalSickle cell Sickle cell disease, abnormal hemoglobins, is due to a single amino acid substitution.

43 What Determines Protein Conformation? Protein conformation depends on the physical and chemical conditions of the protein’s environment Temperature, pH, etc. affect protein structure

44 Denaturation is when a protein unravels and loses its native conformation (shape) Denaturation Renaturation Denatured proteinNormal protein Figure 5.22

45 Types of Proteins

46 Nucleic Acids Nucleic acids store and transmit hereditary information Genes –Are the units of inheritance –Program the amino acid sequence of polypeptides –Are made of nucleotide sequences on DNA

47 Nucleic Acids Provide blueprint of life Nucleotides are the monomers that make –DNA –RNA –ATP Nitrogen Base Pentose (5 carbon sugar) Phosphate

48 Nucleotide Bases Pyrimidines C = Cytosine T = Thymine U = Uracil Purines A = Adenine G = Guanine CH Uracil (in RNA) U Ribose (in RNA) Nitrogenous bases Pyrimidines C N N C O H NH 2 CH O C N H HN C O C CH 3 N HN C C H O O Cytosine C Thymine (in DNA) T N HC N C C N C CH N NH 2 O N HC N H H C C N NH C NH 2 Adenine A Guanine G Purines O HOCH 2 H H H OH H O HOCH 2 H H H OH H Pentose sugars Deoxyribose (in DNA) Ribose (in RNA) OH CH Uracil (in RNA) U 4’ 5”5” 3’ OH H 2’ 1’ 5”5” 4’ 3’ 2’ 1’

49 Deoxyribonucleic acid (DNA) –Double stranded –Form double helix –Stores hereditary information –Provides instruction for every protein in the body Nucleic Acids

50 Ribonucleic acid (RNA) –Single stranded –Builds proteins –Acts as enzymes –Three types mRNA tRNA rRNA Nucleic Acids

51 Adenosine triphosphate (ATP) –Called Life’s Energy Currency –Single nucleotide –Energy storing phosphate groups –Energy transfer and storage used by all cells –Energy is released by breaking high energy phosphate bond Nucleic Acids

52 Do You Feel Like This? ASK QUESTIONS!!