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Unit 1 ­ Biology and disease

Biological Molecules


Organic Molecules

Organic molecules always contain carbon




EG: Glucose - CH0, Methane - CH, Carbon Dioxide, CO




Carbon can bond to itself as well as other atoms in:

1. Straight Chains




2. Branched Chains (amino acids)

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H

H C H
H O
N C C
H OH
H

3. Ring Structures, EG glucose (carbohydrates)




Saturated and Unsaturated Compounds


Saturated

All single bonds, cannot form anymore




Unsaturated

Contains a double or triple bond which can open up to form a new bond




Carbon can form double bonds…

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C N
Triple bonds are rare but can form between two carbon atoms or a carbon atom and a
nitrogen atom




Many organic compounds are polymers made up of monomers




For every covalent bond made, a unit of water is lost, therefore when you combine
monomers it is called a…

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(EG a dimer is broken down into two monomers by adding one unit of water to break its
one bond)




Carbohydrates

Also called saccharides

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They contain carbon, hydrogen and oxygen.




The basic molecular formula of any carbohydrate is (CHO)n

The ratio of hydrogen to oxygen is 2:1 (H0)

Carbohydrates are important for:

Respiration substrates EG: glucose
Storage EG: starch/glycogen
Structure EG: cellulose

Groups of carbohydrates:

Monosaccharides (ose)
Disaccharides (ose)
Polysaccharides

Monosaccharides

Often called simple…

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EG glyceraldehyde




Pentoses

(CHO)n where n = 5 i.e. CHO

Examples include ribose and deoxyribose

Ribose is an important constituent of RNA and can exist as a straight chain or as a ring
(structural isomers)




Hexoses

(CHO)n where n = 6 i.e. CHO

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Examples include glucose, fructose and galactose which are all isomers of each other

Glucose can exist as two forms, alpha ( ) glucose or beta ( ) glucose.

In alpha glucose the hydroxyl groups on carbon atoms 1 and 4 are below the ring

In beta glucose the hydroxyl groups…

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Method: (explanations)

1. Put 5cm³ of the solution into a boiling tube
2. Add 5cm3 of Benedicts solution (displaces CU² ions)
3. Place in water bath at 100C for 3 minutes (increase rate of reaction as particles gain
kinetic energy and vibrate therefore collide more often)
4. Record colour change…

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sucrose and one was water. We added hydrochloric acid to each solution to break the
glycosidic bond between the glucose and fructose molecules and then added sodium
hydrocarbonate to neutralise the acid. Then we added Benedicts solution as in the sucrose
solution there would now be a glucose and a…

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General fomula: (CHO)n ­ (n-1)(HO)

Polysaccharides can be straight or branched chains

They are:

Not sweet
Insoluble in water
Non reducing sugars

EG: Starch, Glycogen, Cellulose

Starch

Well suited to its function because it is:

Compact
Insoluble
Cannot move out the cell in which it is stored
No osmotic effect…

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