A level biology AQA Biological molecules

_wekohgdkates_- Carbohydrates
Monomer One of small molecules that combine to form larger known
many
-

a one

as a
polymer .




Polymer a
large molecule made up of
repeating smaller units ( monomers )
-




monosaccharides Amino acids nucleotides } monomers

v v v



polysaccharide protein DNA } Polymers


CONDENSATION REACTIONS

◦
A condensation reaction joins two molecules together with the formation of a


chemical bond .
It involves the elimination of water .




H O
H
,
,R IT H
i
R
r l

H- C- ° +
H- C- N H ◦

I Go
-
" H - - -
+ - '
c-
-
c- • -
c- µ H
- _ _
N µ µ N o
'

I
'


ti ti
,

R H R H




HYDROLYSIS REACTIONS
◦
A reaction breaks chemical bond between two molecules and involves
hydrolysis a

the use of water .




H R H R
H
IT
N'
Him
C H +
Oy, H- °

g- Go
- - + N H
c- y *
-
- - -
o µ
-
N µ
- - _

'
µ
'
d R'
'

µ H ti o R H




GLUCOSE

glucose is abundant and
very important monosaccharide
◦ an .




◦
It contains six carbon atoms so it is a hexose
sugar .




◦
It has the general formula C6H / 206
◦
Glucose is the major energy source for most cells
◦
It is so it can dissolve into the bloodstream
highly soluble .




◦
the structure of glucose can be shown in different
ways :




°"
C1H 2OH
41-1201-1
Ti F
-



H '

,/
H C O
, H H
C C
"
H↓\É OH
Ho
OH
H
◦µ
C C

OH

↓, ↓H OH C C
H OH

, °
Glucose exists in different forms called structural isomers .




Two common isomers are alpha and beta glucose

H O H °
H OH
p


<
OH OH H
OH
4-
glucose B- glucose



°
The
only difference between these two isomers is the position of the -
OH
group
attached to carbon 1 .




°
In alpha glucose it is below the carbon and in beta it is above the carbon
glucose




CARBOHYDRATES

Carbohydrates
°
are a group of substances used both as an and as a
energy source
structural material in organisms .




°
All carbohydrates contain carbon , and
hydrogen oxygen .




°
There are 3 main groups of carbohydrates
:




monosaccharides
-




these are simple sugars
they have the general formula ( CH20 )n Where n is between 3- 7

and fructose
examples are
glucose galactose
, .




Disaccharide s
-




these are formed from the condensation of 2

monosaccharides

some common disaccharides include :




Glucose +
glucose = maltose

Glucose + fructose = sucrose

Glucose + Galactose = lactose


monosaccharide disaccharide
monosaccharide
° °
H O H O condensation
H H H H
H H
I
H0 OH HO OH
"°
✓ OH

glycosidic bond
H20

Polysaccharides
These are large molecules ( macromolecules) formed from the

condensation of linked
many monosaccharides ,
which are
by
glycosidic bonds


Polysaccharides are insoluble in water

some examples of polysaccharides are starch ,
Glycogen
and cellulose