Biological molecules Flashcards
what is the bond between two monosaccharides
glycosidic bond
maltose-
sucrose-
lactose-
maltose- two glucose
sucrose- glucose and fructose
fructose- galactose and glucose
Structure and role of glycogen
contains many alpha glucose with the 1,4 and 1,6 glycosidic bonds
- energy storage in animals
- large and compact
- insoluble so doesn’t affect water potential
structure and role of starch
contains the alpha glucose amylose and amylopectin
- amylose- 1,4 and 1,6 glycosidic bond and is unbranched. Coiled so compact to store energy
- amylopectin- 1,6 glycosidic bond, branched
- energy storage in plants
- doesn’t effect water potential
Benedict’s test
- food in liquid form
- Benedict’s reagent
- heat mixture gently in water bath
- brick red means reducing sugar
- if blue add HCl to hydrolyse the non reducing sugar
- add NaOH to neutralise it
then add Benedict’s again and the colour should change to brick red
Triglycerides
- formed by the condensation of one molecule of glycerol and three fatty acids
- large and non polar
- does not affect water potential of cells when stored
- important water source for organisms in dry places
Phospholipids
- one fatty acids of a triglycerides is substituted by a phosphate containing group
- polar so bilayer can form
- hydrophilic head
- structure important for cell recognition
Emulsion test
- liquid food sample
- ethanol and shake
- add water
cloudy = lipid
Primary structure
the order of amino acids
secondary structure
mainly arranged as alpha helix or beta pleated
tertiary structure
secondary but more folded and has 3D structure and contains 3 different bonds
disulphide bridges
not easily broken
hydrogen bonds
numerous and easily broken
ionic bonds
between the carboxyl group and amino group that are not involved in peptide bond, easily broken by pH change
Biuret test
- sample in test tube
- add NaOH
- few drops of very dilute copper sulfate solution and mix gently
- purple means there is peptide bond
induced fit model of an enzyme
When the enzyme and substrate bind they form an enzyme substrate complex, and the structure of the enzyme is altered so that the active site of the enzyme fits around the substrate. This is called the induced fit model.
what are ribosomes formed from
RNA and proteins
RNA and DNA contains
ribose, phosphate group, nitrogen containing base
bonds between bases
hydrogen bonds
bonds between nucleotides
phosphodiester bond
DNA
- double helix
- two poly nucleotide chains
- stable due to phosphodiester backbone that protects more chemically reactive nitrogen
semi conservative replication
- unwinding of double helix
- hydrogen bonds between bases break by DNA helicase
- new DNA nucleotides attracted to exposed bases on template strand and complementary base pairing occurs
- DNA polymerase involved in the condensation reaction that joins adjacent nucleotides
ATP
adenine, ribose and three phosphate molecules
properties of water
- metabolite in many metabolic reactions
- important solvent in which reactions ca occur
- high heat capacity so acts as a buffer in changes of temperatures
- high latent heat of vaporisation provides a cooling effect when it evaporates
- strong cohesion supports column of water in transport of water through cells and produces reface tension where water meets air
structure and role of cellulose
contains many beta glucose
- prevents cells from bursting from high osmotic pressure and is tough and rigid
