FUNBIO 1 2024 Past Paper PDF

Biological molecules: Carbohydrates Class: Foundation Year Course: Fundamentals of Human Biology Code: FUNBIO 1 Lecturer : Dr. Kulwinder Kaur Date : 23-09-2024 THE FOUR CLASSES OF BIOLOGICAL MOLECULES All living things are made up of four classes of large biological molecules: carbohy...

Biological molecules: Carbohydrates Class: Foundation Year Course: Fundamentals of Human Biology Code: FUNBIO 1 Lecturer : Dr. Kulwinder Kaur Date : 23-09-2024 THE FOUR CLASSES OF BIOLOGICAL MOLECULES All living things are made up of four classes of large biological molecules: carbohydrates, lipids, proteins and nucleic acids These are macromolecules - large molecules composed of thousands of covalently connected atoms Macromolecules: the building blocks of life  Biological Molecules FUNBIO. 1 Carbohydrates FUNBIO. 2 Proteins FUNBIO. 3 Lipids and Nucleic Acids  LEARNING OUTCOMES Introduce the four main elements of biological importance. Describe the main classes of organic compounds. Discuss the structure of monosaccharides and the glycosidic bond. Explain polysaccharide structure and describe cellulose, starch and chitin. Discuss the role of carbohydrates in glycosylated compounds 4  Organisation of Living Matter Organism Organ systems work together in a functional organism. Population A population consists of organisms of the same Organ system species. e.g., skeletal system-Tissues and Organism organs make up organ systems. Population Organ system Organ e. g., bone Community The populations of different species Organ that populate the same area make up Tissue a community. e.g., bone tissue-Cells associate to form tissues. Community Tissue Cellular level Ecosystem 1) Atoms and molecules make up the Cell A community together with the cytoplasm and form organelles, such as the nonliving environment forms nucleus and mitochondria (the site of many an ecosystem. energy transformations). 2) Organelles perform various functions of Organelle Ecosystem the cell. Macromolecule Biosphere Earth and all of its communities Biosphere constitute the biosphere. Chemical level 1) Atoms join to form molecules. 2) Macromolecules are large molecules Molecule Hydrogen atoms such as proteins and DNA. Oxygen atom Water  Biomolecules consist of compounds Carbohydrates: Sugar Monosaccharides, disaccharides, polysaccharides Proteins:Amino acids, Primary, secondary, tertiary, quarternary structure Lipids: Saturated, unsaturated, trans fats Nucleic Acids: DNA and RNA All four classes are organic molecules! * Not all organic molecules are part of one of the four classes of biological molecules! Why are these compounds so important? Building block of life Constitute the structure of cells and tissues Participate & regulate metabolic reactions Transmit information Provide Energy for life Type of macromolecule Example Function Lipids Fat Cell membrane, Energy storage Carbohydrates Sugar Energy source, Structure Nucleic Acids DNA, RNA Storage and expression of genomic information. Proteins Collagen Structural support, Repair cells and make new ones  Polymer & Monomer Polymer - a long molecule consisting of many similar building blocks Monomer – the building block Three of the four classes of life’s organic molecules are polymers :Carbohydrates, Proteins and Nucleic acids Monomer Polymer  Carbohydrates Carbohydrates (carbo= carbon, hydrate=water) are composed of Carbon, Hydrogen and Oxygen in a 1:2:1 ratio Carbohydrates include –Sugar –Starch –Cellulose –Chitin Sugars and starch are energy sources for cells Cellulose and chitin are structural components Carbohydrates are composed of sugar units – saccharides Monosaccharides, Disaccharides and Polysaccharides  Carbohydrates – Sugar/Starch One sugar unit – Monosaccharides (CH2O) e.g. Glucose [a metabolic fuel, used as an energy source] Two sugar units - Disaccharides e.g. Sucrose (glucose + fructose) [table sugar, found in sugarcane] Many sugar units – Polysaccharides e.g. Starch [Energy stores]  Glucose Glucose is the most abundant monosaccharide C6H12O6 often drawn as linear skeletons, in aqueous solutions many sugars form rings. It is used as an energy source in most organisms It is oxidised by the cell in cellular respiration (CO2+H2O) It is used as a component in the synthesis of other compounds such as amino acids and fatty acids.  Glycosidic Bonds Join sugars together Monosaccharides can be joined together via glycosidic bonds to create polymers of disaccharides, and polysaccharides (condensation reaction) Enzyme Invertase Glucose Fructose Sucrose C6H12O6 C6H12O6 C12H22O11  Common Disaccharides Lactose Galactose- b(1-4)-glucose Maltose Glucose- a(1-4)-glucose  Common Disaccharides In the cyclic form of the sugar, the hydroxyl group (-OH) attached to the anomeric carbon can be positioned either above or below the plane of the ring. The anomeric carbon is the carbon atom in a sugar molecule that was originally part of the carbonyl group (aldehyde (CHO) or ketone (C=O)) in its linear form. This carbon becomes a new chiral center when the sugar cyclizes to form a ring structure. 𝛂-Glucose α: The hydroxyl group is on the opposite side of the ring relative to the CH₂OH group attached to the chiral center. β -Glucose β: The hydroxyl group is on the same side of the ring as the CH₂OH group. 1 carbon of left ring+4th carbon of right ring: alpha or beta(1-4) Sucrose Common table sugar Extracted from sugarcane Hydrolysed by the enzyme Invertase to an equimolar mixture of glucose and fructose Enzyme Invertase Glucose Fructose Sucrose C6H12O6 C6H12O6 C12H22O11 Maltose Glucose+ Glucose(same) A homodimer of glucose units Occurs as a by-product of starch enzymatic hydrolysis (addition of water) Degraded to glucose by enzyme maltase  Lactose Lactose Lactose Sugar found in milk Inability to digest the sugar in milk (lactose intolerance) Caused by a lack of the enzyme lactase, which hydrolyzes lactose into its monosaccharides glucose and galactose Bacteria (b-Galactosidase) in your gut can metabolize it through fermentation though, which produces hydrogen, carbon dioxide, and methane  Polysaccharides Polysaccharides Means “Many sugars” Thousands of monosaccharide rings joined by glycosidic linkages usually Glucoses They are the most abundant carbohydrates in nature Include Starch, Glycogen, Cellulose and chitin It may be a long single chain or a branched chain Enzymatic or acid hydrolysis will release monosaccharides Two types of polysaccharides: Storage and Structural  Storage Polysaccharides Storage Polysaccharides Any polysaccharide that serves as a form of stored energy in living organisms These are often branched and found in plants (Starch), organism (Glycogen) and deposited as granules in the cytoplasm Starch A homopolymer of 𝛂-Glucose units joined by glycosidic bonds Two forms; (i) 𝛂-Amylose (ii) Amylopectin Parenchyma cells of the potato, showing the central cell with obvious nucleus and purple- stained starch X83.  a - Amylose 𝛂 - Amylose A long unbranched chain of glucose units linked by a(1-4) bonds Mw ~ 2,000 - 500,000 Daltons Not truly water-soluble but forms aggregates  Amylopectin Amylopectin A highly-branched polymer, branch length ~ 24 - 30 glucose residues (depending on the species) Backbone linkages = a(1-4) Branch-points = a(1-6)  Hydrolysis of Starch (i) Hydrolysis of Starch (i) The a-Amylase enzyme: – Found in saliva – Important in the digestion of starch - Cleaves a(1-4) bonds randomly to produce a mixture of glucose and maltose  Hydrolysis of Starch (ii) Hydrolysis of Starch (ii) Starch undergoes hydrolysis in diluted solutions of acids at high temperature The b-Amylase enzyme: Cleaves single maltose units successively from the non-reducing end of the polymer Specific for a(1-4) bonds  Hydrolysis of Starch (iii) Both a- and β-amylases degrade a- amylose to completion They will also degrade amylopectin but cannot break down a(1-6) bonds A debranching enzyme, a(1-6) glucosidase, is needed for complete degradation  Glycogen Glycogen is the stored form of glucose that's made up of many connected glucose molecules. A main source of energy that your body stores primarily in your liver and muscles. Your body needs carbohydrates from the food you eat to form glucose and glycogen. Glycogen is the stored form of glucose that’s made up of many connected glucose molecules.  Polysaccharide – Cellulose Cellulose is the most abundant carbohydrate on the planet It makes up over 50% of carbon compounds in plants It is a structural carbohydrate Wood is about 50% cellulose Cotton is about 90% cellulose The cell walls of plants are cellulose The bonds between the glucose units are β(1-4) glycosidic linkages Humans and most animals do not have the enzymes necessary to break these bonds Cellulose only provides roughage in the diet. Cellulose fibers in the plant cell wall.  Polysaccharide – Chitin Chitin is a structural carbohydrate found in animals It is the main component in the cell wall of fungi It also forms the external skeleton of insects, crayfish and other arthropods  Glycoproteins A type of conjugated protein with shorter, branched carbohydrate chains (e.g. Integral membrane proteins) Cell-Cell Recognition and Communication Regulate Cellular Adhesion Regulation of cell signalling Plays an important role in immunity  Phosphorylated Sugars Phosphorylation:A process in which a phosphate group is added to a molecule, such as a sugar or a protein for the regulation of many cellular processes including cell cycle, growth, apoptosis and signal transduction pathways. Phosphorylation is the most common mechanism of regulating protein function and transmitting signals throughout the cell. Phosphorylation of sugars is often the first stage in their catabolism Metabolic intermediates are small molecules essential for the maintenance of cellular homeostasis Phosphorylated sugars occur as intermediates in energy-yielding metabolism – e.g. Glucose-6-phosphate (glycolysis); first intermediate of glucose metabolism Several of the reactions involve the phosphorylation of intermediates, which is important not only for the production of ATP from ADP, but also as a useful handle on the substrate for enzyme binding Phosphorylation also makes sugars anionic and allows some of them to participate in in glycosidic bonding as reactive intermediates Phospholated sugar is most reactive  Reading Chapter 3 ‘The Chemistry of Life’ Organic Compounds Solomon 10th Ed. p44 -54 Chapter 1 ‘A view of Life’ Solomon 11th Ed. p6 -7 Thank you F O R M O R E I N F O R M AT I O N P L E A S E C O N TA N T NAME SURNAME EMAIL: [email protected]