Zusammenfassung der Ressource
Carbohydrates
- Formulas
- Monosaccharide's-
(CH20)n
- 1-Sweet
tasting
2-soluble
3-atoms form
a ring shape.
- Disaccharide's-
2(CH20)n-H2O
- Reactions
- Condensation-
Joins molecules
making water.
- Hydrolysis-
Separates
molecules
using water.
- Glucose- (monosaccharide.)
- C6H12O6
- alpha-glucose.
- Two alpha-glucose monosaccharide's can
join together to make a disaccharide.
- alpha-glucose + alpha-glucose:
maltose + water.
- Can also go backwards in
a hydrolysis reaction to
form two alpha-glucose
molecules from maltose
and water.
- Forms a glycosidic bond
when the hydroxide group
and oxygen are removed to
form a COC bond.
- beta-glucose.
- Disaccharides
- Sucrose
- Made from
glucose and
fructose.
- Maltose
- Made from two
glucose molecules.
- Lactose
- Made from
galactose
and glucose.
- Tests for sugars.
- Reducing sugars.
- All monosaccharide's
and some
disaccharides are
reducing sugars.
- Benedict's Test
- 1- Add sample to a test tube. 2- Add ten drops
of benedicts reagent. 3- Heat to 90 degrees in a
water baths. 4- Observe a colour change.
- If reducing sugars are present then
it will change colour to a red/brown.
Depending on its concentration it
may even turn green, indicating there
is a very low concentration.
- Non-reducing sugars.
- This test is more complicated as the sugars, if present first
have to be broken down by acid hydrolysis to produce the
reducing sugars like monosaccharide's and some disaccharides.
- 1- Add sample to a test tube. 2- Add HCl and heat in a water bath (acid
hydrolysis). 3- Leave to cool and add sodium hydrogencarbonate powder to
make to solution neutral. 4- Add ten drops of benedicts reagent and observe
a colour change.
- If non-reducing sugars are present
then the colour will change as above.
- This test should only be
completed once there is
a negative result for
reducing sugars.
- Polysaccharides.
- Starch.
- Test for starch is to
add iodine. If starch is
present it will turn
brown/black, depending
on concentration.
- Made of
alpha-glucose;
they're
unbranched.
- They're a good energy
store and respiratory
substrate found in
grains in potato tubers,
seeds and stoma of
chloroplasts.
- Properties: Compact, too big to pass through
membranes, insoluble- osmotically inactive,
many glucose molecules, arranged in a helix.
- Glycogen
- Made of alpha-glucose and found in
humans in the liver and muscles. Also
found in fungi and bacteria.
- They're branched
and act as a quick
energy release
stores and
regulate blood
glucose levels.
- Properties:
branched,
insoluble
and tightly
coiled.
- Cellulose.
- Properties: Mechanically
strong, inverted arrangement
of successive glucose
molecules forming hydrogen
bonds, tightly crossed-linked
to form micro fibrils and
fibres, interwoven, gaps allow
permeability.
- Made of
beta-glucose;
they're
unbranched.
- They're good at maintaining cell wall
turgidity- leaves held in place and
stem flexible but firm in the wind.