Lecture notes
A level biology AQA Biological molecules
Lecture notes study book AQA A Level Biology Revision Guide of David Applin (Biological molecules) - ISBN: 9780198351795, Edition: 1, Year of publication: - (A* notes)
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_wekohgdkates_- CarbohydratesMonomer 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
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