biochem

Question 1

what is a polymer

Answer 1

long links of monomers joined together

Question 2

how are monomers often joined together

Answer 2

condensation polymerisation

Question 3

what is lost in condensation reactions

Answer 3

water

Question 4

how are polymers broken down

Answer 4

hydrolysis

Question 5

what are carbon-containing molecules known as

Answer 5

organic molecules

Question 6

in carbs what is the basic monomer unit called

Answer 6

monosaccharide

Question 7

what is the general formula for mono/poly saccharides

Answer 7

(CH2O)n

Question 8

examples of monosaccharides???????

Answer 8

glucose, galactose, fructose

Question 9

how to make maltose, no recipe involved pls +thk

Answer 9

two alpha glucoses joined by glyosidic bonds in a condensation reaction

Question 10

where is the alpha glucose OH group

Answer 10

on the bottom

Question 11

beta glucose OH group placement?????

Answer 11

top

Question 12

what is an isomer

Answer 12

two or more compounds of the same formula but in a differnet arrangement, alpha and beta glucose are examples of this.

Question 13

what is a reducing sugar

Answer 13

a sugar that can donate electrons to another chemical, in the case of testing it will be benedicts reagent

Question 14

what kind of solution is benedicts reagent

Answer 14

alkaline solution of copper(II) sulphate

Question 15

what happens when a reducing sugar is heated with benedicts reagent?

Answer 15

an insoluble red precipitate pf copper oxide (I) forms

Question 16

why do large molecules often contain carbon?

Answer 16

they very readily form bonds with other carbon atoms this allows a sequence of carbon atoms of various length to be built up

Question 17

ehat happens when glucose and fructose join

Answer 17

sucrose

Question 18

what happens when glucose and galactose join

Answer 18

lactose

Question 19

what is a non-reducing sugar

Answer 19

they do not change the colour of benedicts reagent e.g. sucrose

Question 20

how are you able to detect a non-recuing sugar?

Answer 20

• 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