Organic Compounds Organic Compounds The big four are

Organic Compounds

Organic Compounds • The big four are – carbohydrates

Organic Compounds • The big four are – Carbohydrates – lipids

Organic Compounds • The big four are – Carbohydrates – Lipids – proteins

Organic Compounds • The big four are – Carbohydrates – Lipids – Proteins – Nucleic acids

Organic Compounds • Each has a specific role within a cell

Organic Compounds • Each has a specific role within a cell • They all have in common two reactions which are used to form them or break them down. These are the dehydration synthesis reaction and hydrolysis reactions.

(a) Dehydration synthesis Monomers are joined by removal of OH from one monomer and removal of H from the other at the site of bond formation. Monomer 1 + Monomer 2 Monomers linked by covalent bond

(b) Hydrolysis Monomers are released by the addition of a water molecule, adding OH to one monomer and H to the other. Monomer 1 Monomers linked by covalent bond + Monomer 2

Organic Compounds Carbohydrates include sugars and starches and are classified into 3 groups depending on the number of sugars.

Organic Compounds Carbohydrates include sugars and starches and are classified into 3 groups depending on the number of sugars. These are monosaccharides, diassacharides and polysaccharides

Organic Compounds Monosaccharides Most common example is glucose but there are many structural isomers, for example, Fructose and Galactose

Organic Compounds Monosaccharides Most common example is glucose but there are many structural isomers, for example, Fructose and Galactose These all share a formula of C 6 H 12 O 6

Organic Compounds Monosaccharides are used as building blocks for more complex carbohydrates and for cell respiration and formation of ATP.

Organic Compounds

Organic Compounds Disaccharides are double sugars and are formed from two monosaccharides.

Organic Compounds Disaccharides are double sugars and are formed from two monosaccharides. Common disaccharides are: sucrose

Organic Compounds Disaccharides are double sugars and are formed from two monosaccharides. Common disaccharides are: sucrose lactose

Organic Compounds Disaccharides are double sugars and are formed from two monosaccharides. Common disaccharides are: sucrose lactose & maltose

(b) Disaccharides Consist of two linked monosaccharides Example Sucrose, maltose, and lactose (these disaccharides are isomers) Glucose Fructose Sucrose Copyright © 2010 Pearson Education, Inc. Glucose Maltose Galactose Glucose Lactose

Organic Compounds Disaccharides are too large to pass through cell membranes and are broken sown by hydrolysis reactions to monosaccharides.

Organic Compounds Polysaccharides are polymers of simple sugars.

Organic Compounds Polysaccharides are polymers of simple sugars. They are large insoluble molecules and are used for storage of excess carbohydrates or as part of a complex cell membrane molecule.

(c) Polysaccharides Long branching chains (polymers) of linked monosaccharides Example This polysaccharide is a simplified representation of glycogen, a polysaccharide formed from glucose units. Glycogen Copyright © 2010 Pearson Education, Inc.

Organic Compounds Glycogen is a common storage carbohydrate found in the liver and muscle tissue. Glycoproteins are combinations of proteins and sugars. They make up a portion of the surface of the cell membrane and often serve as receptors.

Organic Compounds

Organic Compounds Lipids are nonpolar molecules and are insoluble in water. There are several classes of lipids: q. Triglycerides

Organic Compounds Lipids are nonpolar molecules and are insoluble in water. There are several classes of lipids: q. Triglycerides q. Phospholipids

Organic Compounds Lipids are nonpolar molecules and are insoluble in water. There are several classes of lipids: q. Triglycerides q. Phospholipids qsteroids

Organic Compounds Triglycerides are neutral fats and are composed of fatty acids and glycerol.

Organic Compounds Triglycerides are found primarily beneath the skin and serve as insulation and long term energy storage.

(a) Triglyceride formation Three fatty acid chains are bound to glycerol by dehydration synthesis + Glycerol 3 fatty acid chains Copyright © 2010 Pearson Education, Inc. Triglyceride, or neutral fat 3 water molecules

(b) “Typical” structure of a phospholipid molecule Two fatty acid chains and a phosphorus-containing group are attached to the glycerol backbone. Example Phosphatidylcholine Polar “head” Nonpolar “tail” (schematic phospholipid) Phosphoruscontaining group (polar “head”) Copyright © 2010 Pearson Education, Inc. Glycerol backbone 2 fatty acid chains (nonpolar “tail”)

Organic Compounds Phospholipids are modified triglycerides and make up an important part of the cell membrane.

Organic Compounds The fatty acids that make up a triglyceride or phospholipid can be classified as saturated or unsaturated.

Organic Compounds The fatty acids that make up a triglyceride or phospholipid can be classified as saturated or unsaturated. Fatty acids also vary in length and are usually 14 to 20 carbons in length.

Organic Compounds Saturated fatty acids have only single covalent bonds and can pack closely together. .

Organic Compounds Unsaturated fatty acids have one or more double covalent bonds and do not pack closely together.

Organic Compounds Trans fatty acids are unsaturated fatty acids that have had some of the double bonds converted to single covalent bonds. Problem, we don't have enzymes to break them down.

Organic Compounds Steroids are structurally not related to the other lipids but are classified as such because they are nonpolar. Most common is cholesterol.

Four interlocking hydrocarbon rings form a steroid. Example Cholesterol (cholesterol is the basis for all steroids formed in the body) Copyright © 2010 Pearson Education, Inc.

Organic Compounds Proteins make up 10 to 30 % of the body’s mass. They play many roles in the cell including: q Structural

Organic Compounds Proteins make up 10 to 30 % of the body’s mass. They play many roles in the cell including: q Structural q Enzymes

Organic Compounds Proteins make up 10 to 30 % of the body’s mass. They play many roles in the cell including: q Structural q Enzymes q Hormones

Organic Compounds Proteins are made up of 20 amino acids. Each amino acid has unique properties and when linked together with other amino acids, forms a unique protein.

Amine group Acid group (a) Generalized structure of all amino acids. (b) Glycine is the simplest amino acid. Copyright © 2010 Pearson Education, Inc. (c) Aspartic acid (d) Lysine (an acidic amino acid) (a basic amino acid) has an acid group has an amine group (—COOH) in the (–NH 2) in the R group. (e) Cysteine (a basic amino acid) has a sulfhydryl (–SH) group in the R group, which suggests that this amino acid is likely to participate in intramolecular bonding.

Organic Compounds Proteins are joined or broken down by hydrolysis or dehydration synthesis reactions

Dehydration synthesis: The acid group of one amino acid is bonded to the amine group of the next, with loss of a water molecule. Peptide bond + Amino acid Copyright © 2010 Pearson Education, Inc. Amino acid Hydrolysis: Peptide bonds linking amino acids together are broken when water is added to the bond. Dipeptide

Organic Compounds Proteins can be described in terms of four structural levels. 1. Primary Structure is the amino acid sequence

Levels of protein structure. Amino acid Amino acid Primary structure: The sequence of amino acids forms the polypeptide chain. Copyright © 2010 Pearson Education, Inc.

Organic Compounds Proteins can be described in terms of four structural levels. 2. Secondary Structure is brought about by hydrogen bonds between neighboring amino and carboxylic acid groups.

Organic Compounds Proteins can be described in terms of four structural levels. 2. Secondary Structure is brought about by hydrogen bonds between neighboring amino and carboxylic acid groups. Two forms can exist, the alpha Helix and the Beta sheet.

Levels of protein structure. a-Helix: The primary chain is coiled to form a spiral structure, which is stabilized by hydrogen bonds. b-Sheet: The primary chain “zig-zags” back and forth forming a “pleated” sheet. Adjacent strands are held together by hydrogen bonds. (b) Secondary structure: The primary chain forms spirals (a-helices) and sheets (b-sheets). Copyright © 2010 Pearson Education, Inc.

Organic Compounds Proteins can be described in terms of four structural levels. 3. Tertiary Structure is superimposed on the secondary structure. This represents the shape of the entire protein. It is usually described as globular or fibrous.

Tertiary structure of prealbumin (transthyretin), a protein that transports the thyroid hormone thyroxine in serum and cerebrospinal fluid. ( Superimposed on secondary structure. a-Helices and/or b-sheets are folded up to form a compact globular molecule held together by intermolecular bonds. Copyright © 2010 Pearson Education, Inc.

Organic Compounds. 3. Tertiary Structure is stabilized by covalent bonds of adjacent cysteine amino acids.

Tertiary Structure

Importance?

Organic Compounds Proteins can be described in terms of four structural levels. 4. Quaternary Structure involves the interaction of two or more protein chains. Hemoglobin is an example of this.

Hemoglobin

Organic Compounds What maintains the shape of the protein? q Temperature

Organic Compounds What maintains the shape of the protein? q Temperature q p. H

Organic Compounds What maintains the shape of the protein? q Temperature q p. H q salt concentrations

Organic Compounds What maintains the shape of the protein? q Temperature q p. H q salt concentrations Changes in any of these results in the protein being denatured.

Organic Compounds Remember enzymes?

Organic Compounds Remember enzymes? They are: q substrate specific

Organic Compounds Remember enzymes? They are: q substrate specific q act as a catalyst by reducing the activation energy q action is do to a “lock and key” mechanism

. WITHOUT ENZYME WITH ENZYME Activation energy required Less activation energy required Reactants Product Copyright © 2010 Pearson Education, Inc. Product

Substrates (S) e. g. , amino acids + Product (P) e. g. , dipeptide Energy is absorbed; bond is formed. Water is released. Peptide bond Active site Enzyme (E) Enzyme-substrate complex (E-S) 1 Substrates bind 2 Internal at active site. rearrangements Enzyme changes leading to shape to hold catalysis substrates in occur. proper position. Copyright © 2010 Pearson Education, Inc. Enzyme (E) 3 Product is released. Enzyme returns to original shape and is available to catalyze another reaction.

Organic Compounds Remember DNA? q Contains a deoxyribose sugar

Organic Compounds Remember DNA? q Contains a deoxyribose sugar q Phosphate group

Organic Compounds Remember DNA? q Contains a deoxyribose sugar q Phosphate group q Four bases

Organic Compounds Remember DNA? q Contains a deoxyribose sugar q Phosphate group q Four bases v. Adenine v. Guanine v. Cytosine v. Tyrosine

Phosphate Sugar: Deoxyribose Base: Adenine (A) Thymine (T) Adenine nucleotide . Sugar Phosphate Thymine nucleotide Hydrogen bond (a) Sugar-phosphate backbone Deoxyribose sugar Phosphate Adenine (A) Thymine (T) Cytosine (C) Guanine (G) (b) Copyright © 2010 Pearson Education, Inc. (c) Computer-generated image of a DNA molecule

Organic Compounds Remember RNA? q Contains a ribose sugar q Phosphate group q Four bases v. Adenine v. Guanine v. Cytosine v. Uracil

Table 2. 4 Comparison of DNA and RNA Copyright © 2010 Pearson Education, Inc.

How Does ATP Work? Coupled reactions where stable molecules become phosphorylated and activated

. High-energy phosphate bonds can be hydrolyzed to release energy. Adenine Phosphate groups Ribose Adenosine monophosphate (AMP) Adenosine diphosphate (ADP) Adenosine triphosphate (ATP) Copyright © 2010 Pearson Education, Inc.

Review 1. What are the 3 classes of carbohydrates?

Review 1. What are the 3 classes of carbohydrates? 2. What reaction is used to join simple sugars together?

Review 1. What are the 3 classes of carbohydrates? 2. What reaction is used to join simple sugars together? 3. How do triglycerides and phospholipids differ?