4 - Biological Molecules 1.pdf

Biological Molecules Part 1 Learning objectives Identify the major functional groups and chemical bonds present in organic compounds. Distinguish the different types of biological molecules. Describe the composition, characteristics, and biological functions of the molecules. Macronutri...

Biological Molecules Part 1 Learning objectives Identify the major functional groups and chemical bonds present in organic compounds. Distinguish the different types of biological molecules. Describe the composition, characteristics, and biological functions of the molecules. Macronutrients Carbon – the basic to life ◦ has four valence electrons in its outer orbital ◦ bonds with oxygen, hydrogen, nitrogen, sulfur, phosphorous, and carbon itself, to form complex biomolecules. Organic Molecules ◦ Contain carbon skeletons held together by covalent bonds (C-C , C-H) Is carbon dioxide an organic molecule? Synthesis of Biological Molecules ◦ Water molecule will be released to join two subunits, forming a macromolecule. ◦ Also known as condensation. ◦ Requires water molecule to breakdown macromolecules into smaller subunits. Functional Groups of Biological Molecules  Carbohydrates ◦ Consisting of carbon, hydrogen and oxygen atoms, in the ratio of 1:2:1 ◦ Represented by the formula: (CH 2 O)n Principle subtypes  Reactants in Energy synthesis of storage other biological molecules Functions of Carbohydrates Biologically Structural active components molecules Monosaccharides ◦ Simple sugars, subunits of polysaccharides ◦ Consists of 3-7 carbon atoms ◦ Most carbon atoms are attached to hydrogen and hydroxyl groups ◦ Water-soluble, forms a ring structure ◦ Immediate source of energy Disaccharides ◦ Two monosaccharides linked by dehydration synthesis ◦ Glycosidic bond is formed between the anomeric carbon of one monosaccharide and a hydroxyl oxygen of another ◦ Short-term energy storage in plants Polysaccharides ◦ Repeating units of monosaccharides, usually glucose ◦ Energy storage: Glycogen in animals Starch in plants ◦ Provides structural support Cellulose in plants Chitin in shell of crustaceans, exoskeletons of insects and cell walls of fungi  Less stable More reactive Physical and biological properties of polysaccharides depend on the arrangement of subunits Alpha form is less stable due to the steric hindrance caused by orientation of hydroxyl groups. However, it is readily broken down by enzymes. More stable Less reactive  Branched  (1 − 6)  (1 − 4) Physical and biological properties of Linear polysaccharides depend on the arrangement of subunits Starch ◦ composed of α-glucose molecules: amylose with α-1,4 link amylopectin with α-1,6 link ◦ Water-insoluble, stored as granules in plastid. Glycogen ◦ similar to starch, but extensively branched with more α-1,6 linkages ◦ more soluble in water. ◦ stored in liver and muscle tissues. Cellulose ◦ made of β-glucose molecules with β-1,4 linkage cross-linked by hydrogen bonds. ◦ water-insoluble ◦ cell wall component Chitin ◦ made of β-glucose molecules with β-1,4 linkage, bearing nitrogen- containing functional group at carbon 2 ◦ building material that gives strength to the exoskeletons of crustaceans, insects, and the cell walls of fungi Other polysaccharides ◦ Hyaluronic acid in synovial fluid - for lubrication Heparin in blood – as anticoagulant https://www.turito.com/blog/biology/what-are-polysaccharides Proteins ◦ comprised of one or more chains of amino acid residues joined together by peptide bonds Amino acid structure Variable R group Determines the property of amino acid ◦ Size ◦ Water solubility ◦ Electrical charge / pH ◦ Formation of disulphide bridge (cysteine) Dehydration synthesis of protein  Peptide Polypeptide Short chain (3-50 amino acids) Long chain (>50 amino acids) Levels of protein structure sequence of amino acids in a polypeptide chain Levels of protein structure Interactions between atoms of the backbone, forming locally-folded structures such as alpha helix, beta sheet, coils and turns. Levels of protein structure Interactions between the R groups of the amino acids, producing a three-dimensional structure of polypeptide Levels of protein structure Proteins that are made up of multiple polypeptide subunits Bonds stabilizing protein structure  Keratin (secondary) Enzyme Myoglobin Hemoglobin (tertiary) (quaternary) Comparison between subtypes Foldit: A protein folding computer game ◦ Solve puzzles related to protein and drug design, where you can contribute to advanced research on human health! fold.it LIPIDS Lipids ◦ composed mainly of carbon, hydrogen, oxygen atoms, also contain nitrogen, sulfur, and phosphorous in some cases ◦ large regions of non-polar C-C or C-H bonds, therefore they are hydrophobic and water-insoluble. Functions: ▪ source of nutrients ▪ storage form of carbohydrates ▪ energy-storage molecule ▪ structural components of membranes and hormones  mostly do not have ring structures (except cholesterol) Oil and fats 2× more calories per gram than sugars and proteins triglycerides (1 glycerol + 3 fatty acids) are formed via dehydration synthesis / esterification process Waxes ◦ Structurally similar to fats: esters of long-chain fatty acids and alcohols ◦ Highly saturated lipids – solid at outdoor temperature Functions: ▪ Waterproof coating over leaves, stems ▪ Waterproof coating of mammalian fur, insect’s exoskeleton ▪ Beeswax, Spermaceti Steroids four carbon rings fuse together with various functional groups. Cholesterol vital component of the animal cell membrane: to influence fluidity to act as signaling molecule raw material to synthesize other steroids or hormones (testosterone, oestrogen, bile) Phospholipids Similar to structure of triglyceride, but one fatty acid chain is replaced by a phosphate group with a short, polar functional group (typically containing nitrogen) Functions: ▪ Cell membrane component ▪ Absorption of fat, transport of lipid ▪ Cephalin: blood clotting End of slides