Lots of biological molecules are made of lots of monomers joined together in chains (polymers).
Monomers are joined together by condensation in which a water molecule is removed. The
opposite of this (to break down polymers) is hydrolysis. In condensation of polysaccharides,
glycosidic bonds are formed. With polypeptides, peptide bonds are formed. With Lipids, ester
bonds are formed.
Molecules which have the same number and type of atoms, but not structure, are called isomers.
glucose and glucose are isomers. The H and OH on carbon 1 are swapped around.
Carbohydrates
A sugar with 6 carbons is a hexose sugar, and 5 carbons is pentose. Some examples of pentose
sugars are deoxyribose (what DNA is built around) and ribose (in ribosomes and RNA).
sucrose=glucose+ fructose
lactose=glucose+ galactose
maltose=α glucose+α glucose
The Benedict’s test for reducing sugars involves adding heat and benedict’s solution to a sample. A
brick red precipitate forming is a positive result. All mono-saccharides are reducing sugars but some
others, such as the disaccharide maltose, are too. It is a qualitative (non-absolute) test because
colours on a scale are open to interpretation (an absolute scale is quantitative). This test would have
limitations in medical use because it does not give exact data and blood is red so would make the
colours appear different. To test for non-reducing sugars, the sample must first be hydrolysed by
adding dilute hydrochloric acid and putting it in a water bath that’s been brought to the boil. It must
be neutralised with sodium hydrocarbonate as not to inhibit the reaction with the Benedict’s
solution.
Glycogen is made ofα glucose , and is used for energy storage in animals. It has a central chain with
many branches, so it has a large surface area for enzymes to access and break bonds, releasing
energy quickly. Chains are joined with a 1-6 glycosidic bond. It is also compact so stores a lot of
energy in a small space.
Cellulose is made of β glucose in an unbranched, straight chain. Cellulose (and other
polysaccharide) Micro-fibrils (many chains held together by intermolecular hydrogen bonds) make
up cell walls. They have a high tensile strength, and allow plant cells to cope with osmotic pressure.
Monomers are joined together by condensation in which a water molecule is removed. The
opposite of this (to break down polymers) is hydrolysis. In condensation of polysaccharides,
glycosidic bonds are formed. With polypeptides, peptide bonds are formed. With Lipids, ester
bonds are formed.
Molecules which have the same number and type of atoms, but not structure, are called isomers.
glucose and glucose are isomers. The H and OH on carbon 1 are swapped around.
Carbohydrates
A sugar with 6 carbons is a hexose sugar, and 5 carbons is pentose. Some examples of pentose
sugars are deoxyribose (what DNA is built around) and ribose (in ribosomes and RNA).
sucrose=glucose+ fructose
lactose=glucose+ galactose
maltose=α glucose+α glucose
The Benedict’s test for reducing sugars involves adding heat and benedict’s solution to a sample. A
brick red precipitate forming is a positive result. All mono-saccharides are reducing sugars but some
others, such as the disaccharide maltose, are too. It is a qualitative (non-absolute) test because
colours on a scale are open to interpretation (an absolute scale is quantitative). This test would have
limitations in medical use because it does not give exact data and blood is red so would make the
colours appear different. To test for non-reducing sugars, the sample must first be hydrolysed by
adding dilute hydrochloric acid and putting it in a water bath that’s been brought to the boil. It must
be neutralised with sodium hydrocarbonate as not to inhibit the reaction with the Benedict’s
solution.
Glycogen is made ofα glucose , and is used for energy storage in animals. It has a central chain with
many branches, so it has a large surface area for enzymes to access and break bonds, releasing
energy quickly. Chains are joined with a 1-6 glycosidic bond. It is also compact so stores a lot of
energy in a small space.
Cellulose is made of β glucose in an unbranched, straight chain. Cellulose (and other
polysaccharide) Micro-fibrils (many chains held together by intermolecular hydrogen bonds) make
up cell walls. They have a high tensile strength, and allow plant cells to cope with osmotic pressure.
