3A biological molecules Flashcards
function of water in human body
-medium where chemical reactions occur
-transportation of digested products from ileum to other parts of the body, excretory products from from cells to kidney, hormones from glands to body
-key component of protoplasm, lubricants in joins, digestive juices, blood, tissue fluids
-in animals for respiration, digestion hydrolysis regulates body temperature
-plants for
what is a polymer
-long molecule consisting of many similar or identical monomers linked together by covalent bonds
what is condensation reaction
-chemical reaction that occurs when two simple molecules are joined together to form a larger molecule with the removal of one molecule of water
what is a disaccharide and how is it formed
-disaccharides are sugars linked by an O-glycosidic bond
-when dehydration reaction joins two monosaccharides
what is hydrolysis or hydrolytic reaction
-chemical reaction in which a water molecule is needed to break up complex molecule into smaller simpler molecules
types of polysaccharides
-starch is long straight chains of glucose molecules that are energy storage in plant cells
-glycogen is highly branched polymer of glucose molecules, storage of carbs in animals in liver and muscles
-cellulose is straight chain of glucose molecules, structural carbohydrate in plant wall cells
-chitin is polymer of glucose with amino acids attached, primary constituent of exoskeleton
enzyme hydrolysis of starch
-first broken down by amylase, breaking bonds to release maltose
-maltose molecules broken down by maltase, further bond breaking by maltase enzyme releases glucose
what is glycerol and fatty acids and their components
-glycerol is three-carbon alcohol with a hydroxyl group (OH) attached to each carbon
-fatty acids consist of carboxyl group (COOH) attached to a long carbon skeleton
what is an ester linkage
chemical bond formed between a carboxyl group of a fatty acid and a hydroxyl group of an alcohol
why are fats insoluble in water
-water molecules from fats form hydrogen bonds with each other, excluding the fats
function of fats
-source and stored form of energy
-insulation to prevent heat loss
-absorption and transport
-part of cell membrane
-reduces water loss from skin surfaces
-cushion organs
-forms hormones
-flavour to food
what are proteins
-polymers of amino acids held together by peptide bonds, with the amine end of one amino acid linked to the carboxyl end of the next
-order of sequence of AA determine function of protein
protein formation
-AA link up to form polypeptides, bond between two amino acids is strong peptide bonds which are formed in condensation reaction
-polypeptides may in turn be linked up to form longer chains of amino acids, coils held in place by weak bonds
-protein molecule is made up of one or more long chains of amino acids folded together, coiled or folded to give a three dimensional shape
describe the primary, secondary, tertiary and quaternary structure of proteins
primary - linear sequence of amino acids composing of polypeptide chain
secondary - alpha helixes or beta pleated sheets stabilised by hydrogen bonds
tertiary - superimposed folding of secondary structure to form a globular or ball like molecule
quaternary - polypeptides chains liked together in a specific manner
how is protein denatured
-weak bonds broken easily by heat and chemicals such as acids and alkalis, losing protein’s three dimensional shape and hence denatured, involving a loss of function of protein
what is protein denaturation
-protein denatured when it unfolds and loses its 3 dimensional shape, conformation, may be irreversible depending on severity
function of protein and what does protein deficiency lead to
-synthesis of new protoplasm, for growth and repair of worn out body cells
-form hormones, antibodies, enzymes
-pH and fluid balance
-protein deficiency disease in children which is kwashiorkor, swollen stomach, cracked and scaly skin
why and how are proteins digested in the body
-animal cannot directly absorb protein as protein molecules are too large to pass through living cell surface membrane and hence must be broken down by enzyme during digestion
-undergo series of hydrolytic reactions and are first hydrolysed into polypeptides which are hydrolysed into amino acids
-amino acids simpler and smaller molecules than proteins that are soluble in water, small enough to diffuse through living cell surface membrane via carrier proteins or active transport, hence easily absorb into animal’s body
-after entering body cells, linked up again to form protein needed by animal
why are lipids more suitable as a long term storage of energy than carbohydrates and proteins
Lipids release significantly more energy per gram upon metabolism than carbohydrates and proteins, making them a more efficient option for long-term energy storage.
recite food test for starch
-add 2cm3 of starch solution into test tube
-record initial colour
-add 2-3 drops of iodine solution in test tube and record colour change
-blue-black colouration observed when yellow brown iodine mixes with starch solution so starch present
recite food test for reducing sugar
-add 2cm3 of glucose solution and Benedicts solution into test tube and record initial colour for light blue solution
-place test tube containing mixture into boiling water bath for 2-3 minutes and observe and record colour change
-colour changes to green then yellow before brick red precipitate observed so reducing sugar observed
recite food test for fats
-place one drop of oil into test tube and add 2cm3 of ethanol and shake contents thoroughly and record observation
-clear solution observed as oil dissolve in ethanol
-add 2cm3 of water into test tube of oil-ethanol mixture and shake vigorously and record observation
-2 layers initially and now its cloudy white emulsion observed after mixing
how to ensure fair test for food test
-equal volumes of reagents and sample
-equal duration of boiling water for Benedicts test
-avoid contamination by ensuring droppers are not in contact with test tubes
recite food test for proteins
-place 2cm3 of protein suspension into test tube and add 1cm3 of sodium hydroxide solution into test tube and shake thoroughly
-add 1% copper 2 sulphate solution drop wise, shaking after each drop and record observation
-violent solution observed
