B1.1 - Carbohydrates and Lipids

• Covalent bonds are tge strongest bonds found in biological molecules
• Covalent bonds require lots of energy to break so they provide stability
• Carbon has a critical role in the cell because it can form 4 strong covalent bonds to other carbon atoms to give a stable chain, branched chain, or cyclic (ring) chain.
• Covalent bonds are only broken during specific chemical reactions with other molecules. Molecules are attracted to each other by much weaker IMFSs which can be easily broken and reformed.
• Isomerism: carbons ability to form bonds in various ways and with different atoms leads to the formation of isomers (molecules with the same molecular formula but different structures). isomerism increases molecular diversity and complexity.
• Cantenation: carbon can form stable chains of C-C bonds and is responsible for the formation of complex carbon skeletons in organic compounds
• Carbons compatibility with H2O: carbon based molecules are usually hydrophobic. This is crucial for the creation of hydrophobic cell membranes and compartments in cells.
• Functional groups: carbon contains various functional groups (ex. amino, carbonyl, hydroxyl) attached to the carbon backbone - specific chemical properties and reactivity to organic molecules.
• Diverse properties: carbon can range from hydrocarbon to complex macromolecules (ex. DNA) which allows for a wide array of organic compounds with various functions in living systems
• Carbohydrates: Polysaccharides contains disaccharides which are made of 2 monosaccharides
• Lipids: triglycerides made up of 3 fatty acids and glycerol
• R-group: remainder of the organic molecules and has little or no effect on the chemical properties of the functional group
• Organic molecules are made up of carbon and hydrogen (ex. urea, proteins, sugars, and lipids) which are found in living organisms. Hydrocarbons are also organic molecules, but are not in living organisms.
• Inorganic compounds include CO2, H2CO3 (carbonic acid), H2O
• Carbonyl group: Carbon with double bonded oxygen --> C=O
• Alpha glucose is less stable than beta because the hydroxyl group (OH) on carbon 1 points down, positioning it close to carbon 2. This creates a steric hinderance, which causes a spatial strain in the molecule.
• Beta glucose, hydroxyl group points up, reducing the steric hinderance and results in a more stable, low energy configuration.
• Carbohydrates: Composed of carbon, hydrogen, and oxygen usually in a 1:2:1 ration (C6H12O6) and it's main function is to provide energy
• Monosaccharides (simple sugars): basic units of carbohydrates 1. glucose (energy store) 2. fructose (found in fruit) 3. galactose (component of lactose)
• Disaccharides (2 monosaccharides joined by a glycosodic bond): formed by a condensation reaction 1. maltose (glucose + glucose) 2. sucrose (glucose + fructose) 3. lactose (glucose + galactose)
• Glycosodic bond: a covalent bond between monosaccharides in disaccharides and polysaccharides
• Polysaccharides (long chains of monosaccharides): 1. starch (energy store in plants, made of amylose and amylopectin) 2. glycogen (energy store in animals, highly branched) 3. cellulose (structural component in plant cells and made of linear chains of beta glucose)
• Condensation (carbohydrates): joins monosaccharides and forms water
• Hydrolysis (carbohydrates): breaks down polysaccharides and disaccharides into monosaccharides by adding water
• Lipids: composed of carbon, hydrogen, and oxygen but they have a much lower proportion of oxygen compared to carbohydrates. It is also a long term storage for energy and is a structural component in cell membranes.
• Triglycerides: composed of glycerol and 3 fatty acids. Formed by a condensation reaction (forming ester bonds)
• Saturated fatty acids have no double bonds between carbons but unsaturated have 1 or more double bonds
• Lipids store energy and provide more energy per gram than carbs
• Lipids are an insulator as fat serves as a heat insulator
• Lipids are used for protection and surrounds vital organs
• Phospholipids: make up the cell membrane. They are composed of 2 fatty acids, a glycerol, and a phosphate group
• Phospholipids have a hydrophilic head (phosphate group) and a hydrophobic tail (fatty acids), forming the bilayer of cell membranes
• Steroids: examples. cholesterol, testosterone, estrogen
• Cholesterol helps stabilize fluidity of cell membrane
• Waxes: provide protective coating on leaves and fruits of plants and in animal skin
• Esterfication/Condensation (Lipids): formation of triglycerides by joining fatty acids to glycerol
• Hydrolysis (Lipids): breaking down of triglycerides into glycerol and fatty acids
• Carbs: short term energy store and easily soluble in water (except polysaccharides)
• Lipids: long term energy store and insoluble in water (non-polar molecules)
• Unsaturated (cis) - liquid at RTP and is found in plant oils and fatty fish