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Transcript
All organisms contain essential elements. About 25 of the 92 natural elements are known to be essential to life. carbon (C), oxygen (O), make up 96% of living organisms. hydrogen (H) nitrogen (N) Phosphorus (P), sulfur (S), calcium (Ca), potassium (K) The remaining less than 4% Trace elements: are those required by an organism in only minute quantities. Boron, chromium, cobalt, copper, fluorine, iron, manganese, molybdenum, selenium,silicon, vanadium and zinc Chemical content of human body In chemistry, molecules with a backbone of carbon that also contain hydrogen are called organic molecules. The other atoms and molecules necessary for life are inorganic. carbohydrates, proteins, lipids and nucleic acids, our vitamins are considered to be organic. Water, oxygen, carbon dioxide and the minerals needed to sustain life are inorganic. Which Properties of Carbon make it important for the living? 1) Carbon is one of the atoms (elements) that forms covalent bonds to become stable. Each carbon atom makes 4 bonds, in either chains, branching chains or rings of linked carbon atoms. This diversity in bond formation defines different function in life Different bonds in hydrocarbons Single bonds and chain Chain and branched bonds Double bonds in different location Ring shape with single or double bonds 2) Hydrocarbons, may have functional groups Functional groups also create diversity of molecules function just like diversity in bond formation. Examples of Functional Groups Hydroxyl group - OH Amino group - NH3+ Carboxyl group - COOH Phosphate group - PO3Sulfhydryl group - SH 3) Hydrocarbon variations that differ only in the arrangement of atoms are called isomers. Isomers are very important in biology. There are three types of isomers: structural, geometric and enantiomers. Structural isomers vary in their covalent bonding arrangement. Geometric isomers share common covalent bonding, but have different shapes. The differing shape of geometric isomers can dramatically affect their biological function. (This is sometimes called the cis-trans difference.) Enantiomers are isomers that have the same molecular formula but are mirror images of each other. All living organisms are based on the carbon atom. Carbon atoms continually move through living organisms, the oceans, the atmosphere, and the crust of the planet. This movement is known as the carbon cycle. HOW CARBON RECYCLE? Atmosphere Photosynthetic organisms Soil and oceans and burning organic material Gas form back to atmosphere ORGANIC MOLECULES OF ORGANISMS = MACROMOLECULES All organic compounds of the livings are responsible for such things as: Fuel (energy to do cell work and keep us alive) Structure Metabolism Fuel Storage Genetic Information The cells and tissues of virtually all organisms are made up of the same basic molecules. Many of these are substances with which we are familiar: carbohydrates, lipids, proteins and the nucleic acids. They are known as MACRO MOLECULES (large molecules). the chemical processes by which large molecules (polymers or macromolecules) are built from smaller molecules (often called monomers or subunits) that have a common structure. Most of our biological molecules are assembled or broken down using the same types of chemical reactions. Macro molecules or polymers: How they form and how they break down? • formed by joining smaller (monomers) molecules into chains called polymers • Greek “polys “– many, “meros” – part • since during joining of monomers water molecules are released the reaction called “dehydration” reaction monomer monomer monomer monomer monomer monomer monomer Hydrolysis dehydration monomer monomer monomer monomer monomer POLYMER • polymers break down to monomers by using water, reaction called “Hydrolysis” • Greek “hydro” – water, “lyse” - break • two outcomes 1. provides energy 2. provides monomers (building blocks) needed for an organism to synthesize its own macromolecules Carbohydrate (sugar) types: All carbohydrates are composed of one or more monosaccharides. The simple sugars are formed from one (monosaccharide) or two monosaccharides (called disaccharides), and few monosaccharides ( called oligosaccharides) the complex carbohydrates (polymers) are formed from long chains of monosaccharides, are called polysaccharides Carbohydrate Functions • Basic energy source (fuel) for virtually all living organisms • Structural molecules, especially of plants, most fungi and arthropods (e.g., cellulose, chitin) • Fuel reserve molecules (e.g., starch, glycogen) Carbohydrate structure • their monomers are monosaccharides Chemically, contain: Carbon, Hydrogen, Oxygen • The ratio of atoms in a monosaccharide is: (CH2O)n n= 3-6 • The functional groups of monosaccharides are: –OH “Hydroxyl” =O “Carbonyl” • examples of 6 carbon monosaccharides: glucose, fructose, galactose (main energy source of cell, fruit sugar and milk sugar respectively) Disaccharides and polysaccharides • Disaccharides are 2 monosaccharides joined by a dehydration synthesis, which is the removal of a water molecule. Examples of common disaccharides are sucrose, lactose, and maltose Sucrose= table sugar (glucose+fructose) Lactose= breast milk sugar (glucose+galactose) Maltose= formed by breakdown of starch in animals intestine (glucose+glucose) Oligosaccharides • Humans cannot digest oligosaccharides, but the bacteria in our intestines can. • they are formed from 3-10 sugar subunits • also found as part of glycoproteins and play a role in cell recognition/identity. • may be linked to a lipid molecule to form a glycolipid. In water glucose is constantly bending and forming itself into two different ring configurations millions of times a second. In both cases the oxygen at the end of the straight chain attaches itself to the carbon on opposite end. The hydrogen jumps off the oxygen and turns the double-bond oxygen (=O into OH [hydroxide]). Sometimes this OH will end up oriented downward (alpha-glucose), and other times the OH will be oriented upward (betaglucose). Polysaccharides Polysaccharides are formed by joining 100-1000 monosaccharides, by a dehydration synthesis. The common stored polysaccharides are: • Starch (in plants) • Glycogen (in animals) The common structural polysaccharides are: • Chitin • Cellulose Both starch and glycogen are polysaccharides of glucose. Starch is a very long coiled, unbranched or branching chain, with about 1000 glucose molecules in any branch. Glycogen branches frequently (about every 10 or so glucose units) and is more easily broken down. Starch and glycogen are important fuel storage molecules. 1-4 α D glycosidic linkage 1-4 β, D-glycosidic linkage Cellulose • Long chains of glucose • Cellulose is for most living organisms, non-digestible. Few organisms have the enzyme needed to break down cellulose. Cellulose and related compounds form most of what we call fiber. Chitin • Long modified glucose chains, in which a nitrogen-containing functional group replaces one of the hydroxyl groups on each glucose subunit. • Chitin forms the exoskeleton of many invertebrate animals (mostly arthropods) Functions of Lipids 1. long-term energy (fuel) storage (2X that of carbohydrates) 2. insulation 3. Cushion 4. Structural 5. Many hormones (regulatory) Structure of Lipids • carbon • hydrogen • oxygen However – the proportion of oxygen is low, so lipids are mostly hydrocarbons • The chemical structure of fats and oils, the most common lipids,are based on fatty acid as building blocks and an glycerol (type of alcohol) • The terms fats and oils are Fats are "hard" or solid at room temperature, found in animals Oils are liquids at room temperature, found in plants • all lipids are very hydrophobic molecules (fear water, cant dissolve in water) Major types of Lipids 1. Triglycerides commonly known as the fats and oils 2. Waxes 3. Phospholipids 4. Sterols (or steroids) 5. Terpenes Structure of Fats and Oils (the Triglycerides) One molecule of glycerol + 3 fatty acid tails finish with carboxyl group The double bonds in carbon atoms of fatty acids determine the characteristics as saturated or unsaturated triglycerides carboxyl Fatty acids are chains of hydrocarbons 4— 22 carbons long with the carboxyl functional (acid) group at end-----COOH Each carbon within the chain has 2 spots for bonds with hydrogen • If each carbon has 2 hydrogens the fatty acid is saturated (no double bond) • If two carbon atoms are double bonded, so that there is less hydrogen in the fatty acid, it is mono-unsaturated (single double bond) Kink If more than 2 carbon atoms are unsaturated, the fatty acid is polyunsaturated ( many double bonds) WHAT MAKES THEM LIQUID or SOLID? The more polyunsaturated the lipid the more liquid it is in cold temperature. Therefore oils are rich in poly-unsaturated fatty acid tails and thus they are liquid. Fats are poor in polyunsaturated fatty acid tails thus they are solid at cold temperature. The length of fatty acid chain also affect the triglycerides solid or liquid state. The shorter the fatty acid chain the more liquid (lower its melting point), the longer the fatty acid Phospholipid chain the more solid at cold temperature PHOSPHO-LIPIDS Phospholipids are composed of a glycerol molecule with two fatty acids and a phosphate-containing compound attached to the third carbon. Phospholipids are structural molecules forming the major component of all membranes of cells. Phosphate group type Glycerol Fatty acid chain (hydrocarbon) Various phospholipid types are created by different functional groups found at the phosphate group phospholipid structure is highly amphipathic (both hydrophobic & hydrophilic part containing molecule) , ideal for the cell membrane structure that can make micelle formation or bilayer structure in water Hydrophilic portion in the phosphate region Hydrophobic portion in the fatty acid tails Bilayer structure Double layer single layer Phospholipids also make excellent emulsifiers and are used in a number of food and household products. WAXES Do not contain glycerol only has 2 fatty acid tails attached to each other They are extremely hydrophobic They have a rigid, solid structure at "normal" temperatures They provide waterproof, temperature protective layer (ex: fruit skins, fur of animals, plant leaves, ear wax,) STEROIDS Unlike all other lipids they do NOT contain fatty acid tail. Only contains 4 hydrocarbon rings Although rarely found in plants, certain plant steroids, such as the soy flavinoids, are similar in structure to the estrogen hormones of animals. major sex hormones, Vitamin A & D drived from them Water repellent effect of wax on skin Orange skin PROTEINS (Polypeptides): Amino acid structure -central carbon atom surrounded by -amino group -carboxyl group -single hydrogen -variable R group - Polypeptide several amino acids join by peptide bonds dehydration reaction. Central carbon Variable group hydrophobic hydrophilic acidic basic The structure of the R group dictates the chemical properties of the amino acid. R-group can be as simple as Hydrogen atom or a very big molecule. According to R-groups amino acids classified as: 1. nonpolar (hydrophobic) (7 of them) 2. polar (hydrophilic) (8 of them) 3. acidic (2 of them) 4. basic (3 of them) The combination of 20 different amino acids determines the sequence and shape of the protein. ex: aa1+aa2+aa3+aa4 (is one type of protein) whereas aa1+aa3+aa4+aa2 is another type Protein structure can be in 4 different conformation 1. primary structure= chain of amino acids 2. secondary structure= alpha helix or beta sheet 3. Tertiary structure= folding of helices due to interactions between adjacent R-groups 4. Quaternary structure= combination of several polypeptides Active and functional proteins are always in secondary or tertiary structure peptide bonding Hydrogen bonding Bonding types between R groups of amino acids Examples of certain proteins and their structure Wool, skin, hair, nail = secondary structure Uncooked egg cooked egg Enzymes and most other functional proteins like albumin in egg white= tertiary structure Haemoglobin (blood protein that carry oxygen) = quarternary structure Factors that affect the structure of proteins and thus make them nonfunctional --pH change -- high temperature ---heavy metals --- high salt --- organic solvent Change in the structure of protein that destroys its function is called denaturation How do polypeptides vary? 1. Number of amino acids in the chain: 50—1000 2. Which kinds of amino acids there are in the chain (of the 20 types) 3. How many of each kind of amino acid 4. sequence of amino acids NUCLEIC ACIDS Two essential functions 1. information storage • DNA, RNA 2. store and transfer energy • ATP Nucleotides Are the Monomers That Create Polymers of DNA and RNA • Nucleotides have 3 parts 1. sugar (pentose; 5 carbon sugar) • deoxyribose in DNA • ribose in RNA 2. Phosphate 3. Nitrogen-containing base • A,C,G,T in DNA • A,C,G,U in RNA ATP, GTP, TTP, CTP, UTP 5 possible nucletides They always in tri-phosphate form as a monomer DNA -nucleotides connected by phosphodiester bonds - double helix: 2 polynucleotide strands connected by hydrogen bonds -polynucleotide strands are complementary -genetic information is carried in the sequence of nucleotides 2 PPi Hydrogen bonds joins the bases of the two antiparallel (5’-3’ and 3’-5’) strands of DNA Double helix is an antiparallel strands 5’ 3’ A – T (2 Hydrogen bonds) C- G (3 hydrogen bonds) 3’ 5’ RNA -contains ribose instead of deoxyribose -contains uracil instead of thymine -single polynucleotid strand -functions: -read the genetic information in DNA -direct the synthesis of proteins Functions of Nucleotides Components of nucleic acids (which are long chains of nucleotides) Energy carrier molecules (ATP) Energy transport coenzymes (NAD+, NADP+, FAD+) Chemical intracellular messengers Functions of Nucleic Acids Storage of genetic information (DNA) Transmit genetic information from generation to generation (DNA) Transmit genetic information for cell use (RNA)