y3.1: biological molecules 🥞 Flashcards
what is a polymer?
a large molecule composed of many repeated subunits
functions of fats (episode 1)
- lightweight energy storage: one gram of triglyceride yields about twice as much energy as one gram of carbohydrates; triglyceride has about half the mass of carbohydrates for an equivalent amount of energy stored (used by animals that move by speed or flight + seeds dispersed by wind or insects)
- energy store in cold climate: during hibernation / when it is difficult to hunt for food
- heat insulator: fats conduct heat slowly, adipose cells form adipose tissue under skin
functions of fats (episode 2)
- buoyant: fats are less dense than water, give buoyancy and heat insulation to aquatic animals
- absorb shock: act as a protective layer around vital organs
- oxidation of triglycerides produces metabolic water: triglycerides release twice as much water as carbohydrates when oxidised during respiration (fats contain more hydrogen atoms); important for animals that live in the dry, hot desert where water is scarce.
- as a solvent: for fat-soluble vitamins and hormones
- insulating component of myelin sheath: allow rapid transmission of electrical impulses
functions of proteins
- used in the synthesis of new cells; growth and repair of worn-out cells
- biological catalysts: enzymes
- chemical messengers: hormones
- transport proteins: haemoglobin
- structural protein: keratin for hair and nails
- defence of body: antibodies
what is hydrolysis?
hydrolysis is the splitting up of a complex molecule into its component units with the addition of water
why are starch and glycogen suitable as storage materials?
- insoluble in water so they dont affect cell water potential
- macromolecules hence they are unable to diffuse through cell membrane out of the cell
- compact shapes which occupy less space than individual glucose molecules
- easily hydrolysed to glucose when needed
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what are nutrients?
chemical substances in food that provide energy and materials needed by the body
functions of water
- required for hydrolysis (addition of water molecules to split up complex molecules)
- transport of dissolved substances
- photosynthesis
- regulation of body temperature (removal of latent heat of vapourisation)
what is condensation reaction?
condensation is a chemical reaction whereby two or more simple molecules are joined togeether to form a larger molecule with the removal of water
structure of carbohydrates
- consist of carbon, hydrogen and oxygen
- hydrogen and oxygen atoms are in the ratio 2:1
- contain glycosidic bonds
- glucose -> maltose -> starc
building blocks of maltose
glucose + glucose
building blocks of lactose
glucose + galactose
building blocks of sucrose
glucose + fructose
structure of lipids
- consist of carbon, hydrogen and oxygen
- ratio of hydrogen to oxygen is not fixed
- contain ester bonds (O-C=O)
- consist of one molecule of glycerol and three molecules of fatty acids (triglyceride)