biochem Flashcards
what is a polymer
long links of monomers joined together
how are monomers often joined together
condensation polymerisation
what is lost in condensation reactions
water
how are polymers broken down
hydrolysis
what are carbon-containing molecules known as
organic molecules
in carbs what is the basic monomer unit called
monosaccharide
what is the general formula for mono/poly saccharides
(CH2O)n
examples of monosaccharides???????
glucose, galactose, fructose
how to make maltose, no recipe involved pls +thk
two alpha glucoses joined by glyosidic bonds in a condensation reaction
where is the alpha glucose OH group
on the bottom
beta glucose OH group placement?????
top
what is an isomer
two or more compounds of the same formula but in a differnet arrangement, alpha and beta glucose are examples of this.
what is a reducing sugar
a sugar that can donate electrons to another chemical, in the case of testing it will be benedicts reagent
what kind of solution is benedicts reagent
alkaline solution of copper(II) sulphate
what happens when a reducing sugar is heated with benedicts reagent?
an insoluble red precipitate pf copper oxide (I) forms
why do large molecules often contain carbon?
they very readily form bonds with other carbon atoms this allows a sequence of carbon atoms of various length to be built up
ehat happens when glucose and fructose join
sucrose
what happens when glucose and galactose join
lactose
what is a non-reducing sugar
they do not change the colour of benedicts reagent e.g. sucrose
how are you able to detect a non-recuing sugar?
- hydrolyse it into its monosaccharide
- if the sample is not already in solution it must be ground up into water
- add 2cm3 of the food sample to 2cm3 of benedicts reagent in a test tube and filter
- place the test tube in a gently boiling water bath for 5mins
- if the reagent does not change colour, then a reducing sugar is not present
- add another 2cm3 to 2cm3 of dilute HCL, gently heat in a water bath for 5mins
- the HCL will hydrolyse any disaccharide present into its monos
- slowly add some sodium hydrogencarbonate in order yo neutralise the HCL. benedicts doesn’t work in acidic conditions - could test with pH paper to test for alkaline solution
- retest the solution with 2cm3 benedicts, water bath
if non- recuing is present then it will turn orange-brown thi si due to the reducing sugars that were produced from the hydrolysis
