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3446079
Carbohydrates
Description
AQA AS Biology Unit 1 Molecule Structures (2015)
No tags specified
aqa
biology
as
molecule structures
carbohydrates
sugars
2015
a2
a level
sugar
as bio
a levels
Mind Map by
Julia Romanów
, updated more than 1 year ago
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Created by
Julia Romanów
almost 9 years ago
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Resource summary
Carbohydrates
Meaning ' hydrated carbon'
Made up of carbon, oxygen and hydrogen atoms.
Mono-saccharides
Mono- means 'one'
Glucose Fructose Galactose
There are 2 types of Glucose - Alpha and Beta
They are isomers / the same composition but different arrangement of structure (properties & functions may differ)
The difference is that once it form a ring in the A the C1 OH will point down in the B in will be up.
General formula = (CH^2O)n
n = 3-7
Simplest of carbohydrates
Sweet tasting, soluble substances.
Disaccharides
Di- means 'two'
Sucrose Maltose Lactose
Reducing sugars
Using water we can 'undo' the glycosidic bond and separate the sugar into 2 monosaccharides (hydrolisis)
Sucrose = glucose & fructose ( 1,4 glycosidic bond)
Lactose = Glucose & Galactose / 1,4 glycosidic bond
Formed when 2 monosaccharides react e.g A Glucose + A Glucose = Maltose
The C1 OH & C4 HO react to form H20 and a C-0-C bond (glycosidic bond)
Called 'condensation reaction'
Polysaccharides
Poly- means 'many'
Cellulose Starch Glycogen
Non-reducing sugars
Starch 2 forms : Amylose / amylopectin
Compact/ insoluble/ Has no osmotic effect / easily broken down by enzymes when required.
1)Can be stored in smaller spaces
2)Can be stored in water cells without being used up
3)No net movement of water as a cause of starch storage - no cells bursting
4)So plant can quickly respond to changes in glucose levels
Amylose - Simplest form of starch (30%)
1000's of A-glucose in a straight chain (very tight coils) / insoluble- enzymes only 'nibble' at its ends
Amylopectin (70%)
Every 20 or so = branch of a glucose molecule bonded by a condensation reaction.
More ends to 'nibble' from = quicker reaction than amylose when there's a glucose deficit
Glycogen: Animal version of Amylopectin
Difference: branch every 6/7 glucose molecule (instead of 20) very compact
Energy store in animal livers
Animals more active - need more energy in shorter amount of time
Cellulose: B-glucose molecules linked by 1,4 glycosidic bonds
Every other glucose is upside down (alternating pattern)
Rigid, straight and compact structure
many of These end up forming microfibrils of cellulose
bonded together by hydrogen bonds of adjacent cellulose chains
H-H bonds are weak but in the masses are quite strong
Starch test : Iodine test
Add iodine dissolved in potassium iodide to sample.
If it turns black-blue there's starch in it.
If it stays orange there is no starch.
Polymers formed from repeated condensation reactions of monosaccharides
Greek prefixes = Mono/Di/Tri/Tetra/Penta/Hexa/Poly
Triose= carb with 3 carbons
E.g. Glyceraldehyde
C3H6O3
Tetrose = carb with 4 carbons
Pentose = 5 carbons
E.g. Ribose
C5H11O5
Hexose = 6 carbons
E.g. Glucose
C6H12O6
Ketose group (molecule with C=O bond in the middle of chain)
Aldose= C=O bond at the beggining
Hexoses and pentoses are long enough to form ring structures
Glucose: 1) C=O bond breaks 2) C5 loses H and bonds with O instead 3) Broken H bonds with C1
Benedict's Test
Heat sample with benedict's reagent
stays blue
No reducing sugars present
Heat new sample with HCL then neutralise with NaHCO3
Heat with Benedict's reagent
Goes green , yellow, orange, red or brown
Non-reducing sugars present
Stays blue
No non-reducing sugars present
goes green, yellow, orange, red or brown
Reducing sugars present
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