1.0 MOLECULES OF LIFE BY : MDM. NURFAZLINI ISMAIL (MDM FAZ) 1.1 Water 1.2 Carbohydrates 1.3 Lipids 1.4 Proteins 1.5 DNA and RNA molecules faz/molecules of life/2018

faz/molecules of life/2018 1.1 WATER At the end of this topic, students should be able to : Explain the structure of water and properties of water molecule. faz/molecules of life/2018

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Molecular Structure Of Water Water is composed of : 2 hydrogen atoms and 1 oxygen atom. The chemical formula is H2O. Each H is linked to O by a single covalent bond. faz/molecules of life/2018

faz/molecules of life/2018 Covalent bond Hydrogen atoms Oxygen atom faz/molecules of life/2018

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faz/molecules of life/2018 Water is a polar molecule. One end (oxygen) is slightly negative One end (hydrogen) is slightly positive Oxygen is more electronegative than hydrogen. Tends to attract more electrons. faz/molecules of life/2018

faz/molecules of life/2018 The bond angle between the hydrogen and the oxygen is 104.5o Producing an electric dipole. faz/molecules of life/2018

faz/molecules of life/2018 Polarity allows water molecules to form hydrogen bonds with each other The slightly negative regions of one water molecule are attracted to the slightly positive regions of nearby water molecules, forming hydrogen bonds. Each water molecule can form hydrogen bonds with up to four neighbors. faz/molecules of life/2018

faz/molecules of life/2018 Covalent bond Hydrogen bond faz/molecules of life/2018

H O H  – Hydrogen bond  +  –  +  –  +  –  + —— —— Fig. 3-2 Figure 3.2 Hydrogen bonds between water molecules  +

Properties Of Water Molecule Universal Solvent ( Polar Molecule) Low Viscosity High Specific Heat Capacity High Latent Heat of Vaporization High Surface Tension Maximum Density at 4⁰C Due hydrogen bonding between polar water molecules faz/molecules of life/2018

faz/molecules of life/2018 1.2 CARBOHYDRATES At the end of this topic, students should be able to : State the classes of carbohydrates such as monosaccharides, disaccharides and polysaccharides. faz/molecules of life/2018

faz/molecules of life/2018 An organic compound containing the elements carbon, hydrogen, and oxygen. (CH2O)n ; n = no. of carbon atom. Most abundance class of organic compound. Three main classes of carbohydrates: Monosaccharides Disaccharides Polysaccharides faz/molecules of life/2018

faz/molecules of life/2018 Monosaccharides Monosaccharide composed of one sugar unit. Glucose (C6H12O6) is the most common monosaccharide. Monosaccharides serve as : major energy source for cells. Component in the synthesis of other compound. Major nutrients for cell. faz/molecules of life/2018

faz/molecules of life/2018 Monosaccharides molecule contain carbonyl group (-C=O) at only one of C atom and hydroxyl groups (-OH) at all another C atom. Monosaccharides are classified by The location of the carbonyl group (as aldose or ketose) The number of carbons in the carbon skeleton faz/molecules of life/2018

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(a) α and β glucose ring structures Figure 5.7 Starch and cellulose structures (a) α and β glucose ring structures

faz/molecules of life/2018 Disaccharides A disaccharide is formed when two monosaccharides joined by a glycosidic linkage. Glycodisic linkage is a covalent bond formed by a condensation reaction between two MS. Condensation reaction involves the removal of H atom from one sugar and –OH group from another (removal of a water molecule) faz/molecules of life/2018

faz/molecules of life/2018 Main disaccharides: Maltose (glucose + glucose) Sucrose (glucose + fructose) Lactose (glucose + galactose) faz/molecules of life/2018

(a) Dehydration reaction in the synthesis of maltose 1–4 glycosidic linkage Glucose Glucose Maltose (a) Dehydration reaction in the synthesis of maltose 1–2 glycosidic linkage Figure 5.5 Examples of disaccharide synthesis Glucose Fructose Sucrose (b) Dehydration reaction in the synthesis of sucrose

faz/molecules of life/2018 Polysaccharides Polysaccharides, the polymers of sugars, have storage and structural roles The structure and function of a polysaccharide are determined by its sugar monomers and the positions of glycosidic linkages faz/molecules of life/2018

faz/molecules of life/2018 POLYSACCHARIDES faz/molecules of life/2018

Storage polysaccharides Both made up of α glucose monomers. Starch A storage polysaccharide of plants Plants store surplus starch as granules within chloroplasts and other plastids Glycogen Is a storage polysaccharide in animals Humans and other vertebrates store glycogen mainly in liver and muscle cells faz/molecules of life/2018

(a) Starch: a plant polysaccharide Chloroplast Starch Mitochondria Glycogen granules 0.5 µm 1 µm Figure 5.6 Storage polysaccharides of plants and animals Amylose Glycogen Amylopectin (a) Starch: a plant polysaccharide (b) Glycogen: an animal polysaccharide

Structural polysaccharides The polysaccharide cellulose is a major component of the tough wall of plant cells Like starch, cellulose is a polymer of glucose, but made up of β glucose faz/molecules of life/2018

Cell walls Cellulose microfibrils in a plant cell wall Microfibril Fig. 5-8 Cell walls Cellulose microfibrils in a plant cell wall Microfibril 10 µm 0.5 µm Cellulose molecules Figure 5.8 The arrangement of cellulose in plant cell walls Glucose monomer

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faz/molecules of life/2018 1.3 LIPIDS At the end of this topic, students should be able to : State the types of lipids: triglycerides (fat & oil), phospholipids and steroids. faz/molecules of life/2018

General Features of Lipids Lipids contain C, H and O but have a much smaller proportion of oxygen compared to a molecule of carbohydrate The ratio of 0 : H is lower than carbohydrates. The C-H bond is stronger than those in carbohydrates. Stores large amount of energy. Release higher energy when broken down faz/molecules of life/2018

faz/molecules of life/2018 Types of lipids Triglyceride (fats and oil) Triglycerides are constructed from two types of smaller molecules: glycerol and fatty acids Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon A fatty acid consists of a carboxyl group attached to a long carbon skeleton In a fat, three fatty acids are joined to glycerol by an ester linkage, creating a triglyceride faz/molecules of life/2018

Fatty acid (palmitic acid) Glycerol (a) Dehydration reaction in the synthesis of a fat Ester linkage Figure 5.11 The synthesis and structure of a fat, or triacylglycerol (b) Fat molecule (triacylglycerol)

faz/molecules of life/2018 Phospholipid In a phospholipid, two fatty acids and a phosphate group are attached to glycerol The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head Phospholipids are the major component of all cell membranes faz/molecules of life/2018

Choline Phosphate Hydrophilic head Glycerol Fatty acids Hydrophobic tails Figure 5.13 The structure of a phospholipid (a) Structural formula (b) Space-filling model

faz/molecules of life/2018 Steroids Steroids are lipids characterized by a carbon skeleton consisting of four fused rings Cholesterol, an important steroid, is a component in animal cell membranes Although cholesterol is essential in animals, high levels in the blood may contribute to cardiovascular disease faz/molecules of life/2018

Figure 5.15 Cholesterol, a steroid

faz/molecules of life/2018 1.4 PROTEINS At the end of this topic, students should be able to : Describe the basic structure of amino acids State how amino acids are grouped faz/molecules of life/2018

General features of Protein The monomer is amino acids. Amino acids are organic molecules with carboxyl and amino groups, a hydrogen atom and R group side chain. All are covalently linked to the same carbon atom Amino acids are amphoteric molecules. have both acidic (-COOH) and basic (-NH2 ) faz/molecules of life/2018

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faz/molecules of life/2018 Amino acids differ in their properties due to differing side chains, called R groups R groups: Non-polar hydrophobic Polar hydrophilic Electrically charged Basic Acidic faz/molecules of life/2018

faz/molecules of life/2018 NON-POLAR AMINO ACID faz/molecules of life/2018

faz/molecules of life/2018 POLAR AMINO ACID faz/molecules of life/2018

faz/molecules of life/2018 ELECTRICALLY CHARGED faz/molecules of life/2018

faz/molecules of life/2018 1.5 DNA AND RNA MOLECULE At the end of this topic, students should be able to : State the structures of nucleotide as the basic composition of nucleic acids (deoxyribonucleic acid, DNA and ribonucleic acid, RNA) State the types of RNA faz/molecules of life/2018

Structure of nucleotide Nucleotide is the basic unit for nucleic acids. Polynucleotide is made of nucleotides There are two types of nucleic acids: Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) mRNA tRNA rRNA faz/molecules of life/2018

faz/molecules of life/2018 Nitrogenous bases Pentose sugar faz/molecules of life/2018

(c) Nucleoside components: sugars Deoxyribose (in DNA) Ribose (in RNA) Figure 5.27 Components of nucleic acids (c) Nucleoside components: sugars

faz/molecules of life/2018 There are two types of nitrogenous bases: Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring Purines (adenine and guanine) have a six-membered ring fused to a five-membered ring In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose faz/molecules of life/2018

(c) Nucleoside components: nitrogenous bases Pyrimidines Cytosine (C) Thymine (T, in DNA) Uracil (U, in RNA) Purines Figure 5.27 Components of nucleic acids Adenine (A) Guanine (G) (c) Nucleoside components: nitrogenous bases