1.Molecules of Life.pdf

BIOLOGY 1.0: MOLECULES OF LIFE 1.1 WATER 1.2 CARBOHYDRATES 1.3 LIPIDS 1.4 PROTEINS 1.5 NUCLEIC ACIDS  1.0: MOLECULES OF LIFE At the end of this topic, students should be able to: 1.1 Water a) State the structure and properties of water molecules....

BIOLOGY 1.0: MOLECULES OF LIFE 1.1 WATER 1.2 CARBOHYDRATES 1.3 LIPIDS 1.4 PROTEINS 1.5 NUCLEIC ACIDS  1.0: MOLECULES OF LIFE At the end of this topic, students should be able to: 1.1 Water a) State the structure and properties of water molecules. b) Relates the properties of water and its importance.  WATER WATER MOLECULE 1.1 WATER Water has a simple molecular structure. It is composed of one oxygen atom and two hydrogen atoms.  WATER MOLECULE ▪ A hydrogen atoms 1.1 WATER combined with the oxygen atom by sharing of electrons. Angle of water atoms ▪ Each hydrogen atom is covalently bonded to the oxygen via a shared pair of electrons. ▪ Oxygen also has two unshared pairs of electrons. Thus, oxygen is an "electronegative“ compared with hydrogen.  Polarity of water Polar molecule : A molecule with uneven distribution of charges in different regions of the molecules. (Campbell 9th edition) 1.1 WATER  Oxygen region Partially negative side has partial negative of water molecule charge.  Hydrogen has a partial positive charge. Partially positive side of water molecule Ball-and-Stick Model  Bonds of water molecules 1.1 WATER  PROPERTIES OF WATER Universal solvent due to its polarity/ polar molecules 1.1 WATER Low viscosity High specific heat capacity High latent heat of vaporization High surface tension Maximum density at 4°C  1.0: MOLECULES OF LIFE At the end of this topic, students should be able to: 1.2 Carbohydrates a) State the classes of carbohydrates such as monosaccharides, disaccharides and polysaccharides. b) Illustrate the formation and breakdown of maltose. c) Compare the structure and function of starch, glycogen and cellulose.  CARBOHYDRATES Organic compounds 1.2 CARBOHYDRATES containing C, H and O (ratio of 1:2:1) Empirical formula : (CH2O)n  MONOSACCHARIDES Characteristics: Simple sugar 1.2 CARBOHYDRATES Small Sweet tasting Primary source of energy Readily soluble in water Reducing sugar Crystalline  MONOSACCHARIDES Carbon backbone of 3 to 6 carbon atoms. 1.2 CARBOHYDRATES Have a carbonyl group and multiple hydroxyl groups. ALDOSE KETOSE Carbonyl group : C = O CARBONYL CARBONYL Hydroxyl group : OH group is located group is located on the terminal on a carbon carbon in That is not All carbon atoms except the chain. on the end one have a hydroxyl of the chain. group attached.  DISACCHARIDES 1.2 CARBOHYDRATES  Formed by condensation reaction of TWO monosaccharides.  Bond linking : glycosidic bond. Disaccharides:  Characteristics: Maltose Sucrose Water-soluble Lactose Sweet tasting Readily soluble in water Reducing sugar (maltose, lactose) Crystalline 1.2 CARBOHYDRATES DISACCHARIDES  DISACCHARIDES MALTOSE - condensation 1.2 CARBOHYDRATES 1.2 CARBOHYDRATES MALTOSE - hydrolysis DISACCHARIDES  POLYSACCHARIDES Polymers of monosaccharides made up of condensation of 1.2 CARBOHYDRATES hundreds of monosaccharides Polysaccharides: Characteristics: Starch Glycogen - Large and complex Cellulose - Most are not soluble in water - Not sweet tasting - Food storage  POLYSACCHARIDES STARCH Condensation of α-glucose subunits 1.2 CARBOHYDRATES Used for energy storage in plants Made up of two components : 1. Amylose A linear unbranched polymer Glucose units joined by α-1,4 glycosidic bonds 2. Amylopectin A branched polymer linear chains held together by α-1,4 glycosidic bonds short branches: held by α-1,6 glycosidic bonds  GLYCOGEN POLYSACCHARIDES Condensation of α-glucose subunits 1.2 CARBOHYDRATES Major storage of carbohydrate in animals Structure similar to amylopectin : larger & with more branches.  CELLULOSE POLYSACCHARIDES Condensation of β-glucose subunits 1.2 CARBOHYDRATES Structural polysaccharides in plant cell walls Composed of long unbranched chains linked by β -1,4 glycosidic bonds Many hydrogen bonds are formed between hydroxyl groups on parallel chains ( between C atoms 3 and 6).  1.0: MOLECULES OF LIFE At the end of this topic, students should be able to: 1.3 Lipids a) State the types of lipid: triglycerides (fat and oil), phospholipids and steroids. b) Describe the structure of fatty acids and glycerol. b) Explain the formation and breakdown of triglycerides.  LIPIDS Characteristics: Insoluble in water Not polymer Lipids are organic compounds. Have little or no affinity for water (hydrophobic General formula : CnH2nO2 behavior) Soluble in organic solvent Proportion of oxygen is lower than 1.3 LIPIDS such as ether, acetone, in carbohydrates. chloroform and hot alcohol Can store large amount of energy: The ratio of energy storing C-H bonds in fats is more than twice that carbohydrates / more C and H.  LIPIDS TYPE OF LIPIDS - TRIGLYCERIDES i.e Fat and oil - PHOSPHOLIPIDS i.e Lecithin - STEROID 1.3 LIPIDS i.e Cholesterol Testosteron TRIGLYCERIDES: LIPIDS STRUCTURE OF FATTY ACIDS AND GLYCEROL Glycerol is a three-carbon alcohol that contains three hydroxyl group (-OH) a fatty acid is a long, unbranched hydrocarbon chain with carboxyl group (-COOH) at one end. 1.3 LIPIDS  Formation/Breakdown of Triglycerides condensation 1.3 LIPIDS hydrolysis  1.0: MOLECULES OF LIFE At the end of this topic, students should be able to: 1.4 Protein a) Describe the basic structure of amino acid b) State how amino acids are grouped. c) Describe primary, secondary, tertiary and quaternary level of proteins and the type of bonds involved  1.0: MOLECULES OF LIFE At the end of this topic, students should be able to: 1.4 Protein d) Describe the effect of pH and temperature on the structure of protein. e) Explain the formation and breakdown of dipeptide f) Classify proteins according to structure and composition  PROTEINS Molecule made up of one/more polypeptides, each folded and coiled into specific 3D structure. Constructed from amino acids. 1.4 PROTEINS The bond between amino acids is called peptide bond. Each polypeptide has a unique linear sequence of amino acids.  PROTEINS Protein Monomer : Amino acid Amino acid containing an amino group 1.4 PROTEINS a carboxyl group, a hydrogen atom a side chain – that are specific to (R group) each amino acid. a variable group  PROTEINS How amino acids are grouped? Nonpolar amino acid 1.4 PROTEINS The 20 amino acids Polar are grouped amino acid according to the properties of their Acidic side chains (R amino acid groups) Basic amino acid  PROTEINS Proteins Structure The sequence of amino acids determines a protein’s three-dimensional structure. 4 levels of protein structure 1.4 PROTEINS Primary Secondary Tertiary Quaternary (1 ͦ ) (2 ͦ ) (3 ͦ ) (4 ͦ )  Proteins Structure: Primary (1 ͦ ) Primary Structure 1 5 sequence of amino + H3N acids determined by 1.4 PROTEINS Amino end genetic code carried in DNA molecules in the 10 nucleus. 15 Amino acid subunits Eg: Insulin 20 25  Proteins Structure: Secondary (2 ͦ ) Polypeptide chains are coiled (-helix ) and folded (β-pleated sheet). A coiled shape of the -helix 1.4 PROTEINS is held in place by hydrogen bonds between amino groups and the carboxyl groups of the amino acids. Hold protein in a parallel E.g. : keratin in hair, nails, arrangement (β-pleated horn and feathers sheet) with hydrogen bond. E.g.: silk protein of a spider’s web.  Proteins Structure: Tertiary Involves interactions (attractions & repulsions) between R groups of the amino acids Hydrophobic Structure is interactions and van der Waals 1.4 PROTEINS maintained by : interactions –Hydrogen bond Polypeptide backbone –Ionic bond Hydrogen bond –Disulfide bridge –Hydrophobic Disulfide bridge interactions –van der Waals interactions Ionic bond  Proteins Structure: Quaternary Two or more polypeptide chains form one functional macromolecule. 1.4 PROTEINS Combination two or more tertiary units. Stabilized with the same interactions found in tertiary structure.  Factors Affecting Protein Structure Temperature Heat increases the kinetic energy of the protein 1.4 PROTEINS chain. Excessive motion can break relatively weak hydrogen bonds, electrostatic interactions (ionic bond) and hydrophobic interactions. Protein chain is free to rearrange after disrupting. E.g : Fried egg  Factors Affecting Protein Structure pH Extreme of pH can cause protein to denature. 1.4 PROTEINS Change the charges of acidic and basic functional groups of proteins. Those functional groups will lose & gain a proton. Break hydrogen bonds between acidic and basic R groups & disrupt ionic bonds.  The Formation and Breakdown of Dipeptide 1.4 PROTEINS  PROTEIN CLASSIFICATION BASED ON THEIR STRUCTURE Fibrous protein Globular protein Conjugated protein 1.4 PROTEINS Collagen Enzymes Hemoglobin α-keratin Antibodies Elastin Hormones  1.0: MOLECULES OF LIFE 1.5 Nucleic Acids At the end of this topic, students should be able to: a) State the structure of nucleotide as the basic composition of nucleic acid (DNA and RNA) b) Illustrate the structure of DNA based on Watson and Crick model. c) State the types of RNA d) Compare DNA and RNA  NUCLEIC ACIDS NUCLEIC ACIDS Macromolecules (large molecules) made up of 1.5 NUCLEIC ACIDS chains of individual units called nucleotides. Each nucleotide is made up of pentose sugar, phosphate group and nitrogenous bases. 40  NUCLEIC ACIDS Components of Nucleotide 1.5 NUCLEIC ACIDS  NUCLEIC ACIDS Formation of Phosphodiester bond between phosphate group at C5 & Hydroxyl group (OH) at C3 next monomer. 1.5 NUCLEIC ACIDS  NUCLEIC ACIDS Watson and Crick’s DNA Model  A DNA molecule is linkage 1.5 NUCLEIC ACIDS of nucleotides forms long chains called polynucleotides.  A Chemically, one strand G T runs 5’ to 3’ upward while C A T C G the other runs in the opposite direction of 5’ to 3’ downward.  and coiled (clockwise C spiral) into a double helix. G A T 43  NUCLEIC ACIDS RNA Structure A single-stranded polymer of nucleotides 1.5 NUCLEIC ACIDS  NUCLEIC ACIDS Differences of DNA and RNA 1.5 NUCLEIC ACIDS  NUCLEIC ACIDS Differences of DNA and RNA 1.5 NUCLEIC ACIDS  DNA RNA Mostly two polynucleotide chains // Mostly single polynucleotide chain // most double-stranded single-stranded Double helix No double helix Deoxyribose as pentose sugar Ribose as pentose sugar Organic bases: A, T, C, G Organic bases: A, U, C, G * Base thymine (T) * Base Uracil (U) Manufactured in nucleus Manufactured in nucleus but found throughout the cell Chemically very stable// long live Chemically much less stable// temporary Larger molecular size/ mass Smaller molecular size/ mass Only one basic form Many/ 3 basic forms : mRNA, rRNA and tRNA Susceptible to UV damage Relatively resistance to UV damage