2.3 carbohydrates lipids Flashcards
what are macromolecules?
- carbohydrates, lipids, proteins and nucleic acids are called macromolecules because of their large size
- usually consist of repeating units within them with the exception of lipids
- macromolecule that is made up of repeating units are also known as polymers made up of individual monomers
- polymers include polysaccharides, polypeptides and polynucleotides
- monomers include monosaccharides, amino acids and nucleotides
what are monosaccharides?
single sugar molecules with commonly 3 to 7 carbon atoms as their backbone
how do disaccharides form?
when 2 monosaccharides are joined together via a condensation (dehydration) reaction
- maltose: glucose + glucose
- lactose: glucose + galactose
- sucrose: glucose + fructose
what are polysaccharides?
polymers of monosaccharides
- starch and glycogen are polysaccharides used as energy storage
molecules
- chitin and cellulose are polysaccharides used as structural molecules
what happens during a condensation reaction?
hydroxyl (-OH) group reacts with a variety of other functional groups containing a hydrogen
- in monosaccharides, the hydroxyl group on the 1st carbon reacts with the hydrogen of a hydroxyl group of the 4th carbon of another monosaccharide to form a bond
characteristics of polysaccharides
- not sweet tasting
- low solubility
what are the 2 main functions of polysaccharides?
- energy storage
- structural functions
what is starch?
energy-storing polysaccharide found in plant cells, and tend to have fewer side branches
- amylose (unbranched) and amylopectin (branched) are the two main forms of starch found in plants
what is glycogen?
energy-storing polysaccharide found in animal cells, and tend to have a high number of side branches
- mainly found in the liver and muscles of animals
compare amylose and amylopectin
amylose:
- low degree of branching
amylopectin:
- very high degree of side branching
what is cellulose?
polysaccharide that forms microfibrils
- mainly found in the cellulose cell wall of plant cells
- large component of wood and other plant fibres
- indigestible to most animals
what is chitin?
polysaccharide with an amino side group attached to each glucose monomer
- resistant to wearing, and is relatively hard to digest by animals
- primary structural component of fungi, and the exoskeleton of arthropods
what are lipids?
- diverse group of hydrophobic molecules
- not polymers
- hydrophobic as their fatty acid tails consist of a long chain of hydrophobic hydrocarbons with very little oxygen present
- fats are lipids that are solid at 20 degrees Celsius
- oils are lipids that are liquid at 20 degrees Celsius
- most lipids are triglycerides
• made from one glycerol molecule and three fatty acids
what are triglycerides?
- used as long term energy storage compound in plants and animals
- one glycerol molecule, which is a three carbon alcohol with three hydroxyl groups, and each hydroxyl group is attached to a separate carbon
- fatty acids are long hydrocarbon chains with a carboxylic acid group on one end
- triglycerides formed from the esterification of the three fatty acids with the glycerol, via a condensation reaction, forming three ester bonds
what is the difference between saturated and unsaturated fatty acids?
- saturation referred to here refers to the degree of saturation of the hydrocarbon chains with hydrogen atoms
- unsaturated fatty acid will contain a carbon-carbon double bond, and this double bond can be attacked and a H2 molecule can be used to attach a hydrogen atom to each of the two carbon atom
- saturated fatty acid has no carbon-carbon double bonds present, while a monounsaturated fatty acid has one carbon- carbon double bond present while a polyunsaturated fatty acid has multiple double bonds present
