1. lipids and carbs fact test Flashcards
what is a monomer
the smaller units from which larger molecules are made
what is a polymer
molecules made from a large number of monomers joined together
what are some examples of monomers
monosaccharides, amino acids and nuceotides
what are some examples of polymers
polysaccharides, proteins, polypeptides and DNA
what is a condensation reaction
joins 2 molecules together with the formation of a chemical bond and involves the elimination of a water molecule
what is a hydrolysis reaction
breaks a chemical bond between 2 molecules and involves the use of a water molecule
what are monosaccharides
monomers from which larger carbohydrates are made
what are some common monosaccharides
glucose, fructose and galactose
what does a condensation reaction between 2 monosaccharides form
a glycosidic bond
what are disaccharides
formed by the condensation between 2 monosaccharides
what monosaccharides make the disaccharide maltose
2 glucose molecules
what monosaccharides make the disaccharide sucrose
glucose and fructose
what monosaccharides make the disaccharide lactose
glucose and galactose
what are the 2 isomers of glucose called
alpha glucose
beta glucose
what are polysaccharides
formed by the condensation of many glucose units
what are the 4 polysaccharides
cellulose
starch - amylose
starch - amylopectin
glycogen
what is cellulose like
- found in plants
- unbranched
- made of beta glucose
- bond between monomers is 1-4
- provides strength
- long, straight unbranched chains of beta glucose
joined by hydrogen bonding to form microfibrils which provides strength
what is starch (amylose) like
- found in plants
- unbranched
- made of alpha glucose
- bond between monomers is 1-4
- stores energy
what is starch (amylopectin) like
- found in plants
- branched
- made of alpha glucose
- bonds between monomers are -4 and 1-6
stores energy - branched therefore more ends for faster hydrolysis
what is glycogen like
- found in animals
- branched
- made of alpha glucose
- bonds between monomers is 1-4 and 1-6
- stores energy
- branched therefore more ends for faster hydrolysis
what do amylose, amylopectin and glycogen have in common
- polymer of alpha glucose so easily hydrolysed to provide glucose for respiration
- has coils therefore compact
- made of glucose so provides respiratory substrate for energy release
- insoluble so doesn’t affect water potential/osmosis
- large molecule so can’t cross the cell membrane
what is the test for starch
- grind/crush food sample
- add iodine in potassium iodide solution
- positive result is colour change from orange/brown to blue/black
what are reducing sugars
a reducing sugar is a sugar that can donate electrons (i.e. reduce) another chemical e.g benedict’s reagent
what are some examples of reducing sugars
all monosaccharides and some disaccharides e.g maltose
how do you test for reducing sugars
- add benedict’s solution and heat in a hot water bath
- positive result is colour change from blue to brick red
what are non-reducing sugars
don’t change colour when heated with benedict’s solution
how do you detect non-reducing sugars
sample must first be hydrolysed into it’s constituent monosaccharides
what are some examples of non-reducing sugars
some disaccharides e.g sucrose
what is the test for non-reducing sugars
- first confirm no reducing sugars are present
- get a fresh sample
boil in acid (e.g hydrochloric) which will hydrolyse any dissacharide present into its constituent monosaccharides - neutralise (e.g sodium hydrogen carbonate) as benedict’s reagent will not work in acidic conditions
- add benedict’s reagent and heat in a hot water bath
- observe colour change
what are lipids
- not polymers as they aren’t made up of repeating units
- made up of carbon, hydrogen and oxygen
- insoluble in water, soluble in alcohols
what are the roles of lipids
- cell membranes
- energy source
- water proofing
- insulation
- protection
how do you carry out the emulsion test (test for lipids)
- add ethanol to substance
- add water
- positive result is milky white emulsion
- negative result is colourless
what are triglycerides
1 glycerol molecule bonded to 3 fatty acid chains
3 water molecules are eliminated to make a triglyceride
what is an ester bond
covalent bond between glycerol and fatty acid formed by condensation reaction and broken by hydrolysis reaction
where is the ester bond always formed
the side with the COOH group
what are saturated fatty acids
all C-C single bonds
carbons are fully saturated with hydrogen atoms
tend to form fats
solid at room temperature
what are unsaturated fatty acids
can be monounsaturated - only one C=C double bond
can be polyunsaturated - many C=C double bonds
tend to form oils and are liquid at room temperature
what are phospholipids
1 glycerol bonded to 2 fatty acids and one phosphate group
what does amphiphilic mean
a molecule having both hydrophobic (non-polar) and hydrophilic (polar) regions
e.g. phospholipids
