1. Biological molecules
Carbohydrates
Monosaccharides are the monomers from which larger carbohydrates
are made. Glucose, galactose and fructose are common
monosaccharides. A condensation reaction between two
monosaccharides forms a glycosidic bond.
Disaccharides are formed by the condensation of two
monosaccharides:
• maltose is a disaccharide formed by condensation of two glucose
molecules
• sucrose is a disaccharide formed by condensation of a glucose
molecule and a fructose molecule
• lactose is a disaccharide formed by condensation of a glucose
molecule and a galactose molecule.
Glucose has two isomers, α-glucose and β-glucose, with structures:
Polysaccharides are formed by the condensation of many glucose
units.
• Glycogen and starch are formed by the condensation of αglucose.
• Cellulose is formed by the condensation of β-glucose.
The basic structure and functions of glycogen, starch and cellulose.
The relationship of structure to function of these substances in
animal cells and plant cells. Biochemical tests using Benedict's
solution for reducing sugars and non-reducing sugars and
iodine/potassium iodide for starch.
Monosaccharides are monomers from which larger carbohydrates are made.
Common monosaccharides include glucose, fructose and galactose
A condensation reaction between two monosaccharides forms a glycosidic
bond and a disaccharide
Glucose + glucose = maltose
Glucose + fructose = sucrose
Glucose + galactose = lactose
Glucose has two isomers - alpha (α) glucose and beta (β) glucose
,The position of the hydroxyl groups on carbon 1 are inverted between
alpha and beta glucose
Polysaccharides are formed by the condensation of many glucose units
Glycogen and starch are formed from the condensation of α- glucose
Cellulose is formed from the condensation of β- glucose
Testing for reducing sugars (all mono and disaccharides but
sucrose)
Add 2cm3 of the sample to a test tube, liquidise if necessary, add an equal
amount of benedict's reagent (copper II sulphate and NaOH) , heat in a
boiling water bath for 5 minutes. The test is a semi- quantitative test so it
gradually changes colour from blue to brick red if a reducing sugar is present.
Non - reducing sugars - polysaccharides + sucrose
1. Test for reducing sugars using benedict's solution
2. If you get a negative result you try to break down the polysaccharide
3. Add 2cm3 of the sample to the same amount of HCL. Add to a boiling
water bath for 5 minutes which will hydrolyse the disaccharides into their
monosaccharides
4. Slowly add some Sodium hydrogen carbonate to neutralise the HCL and
test the Ph with the litmus paper to check
5. If a non- reducing sugar was present in the original sample, the benedict's
reagent will turn burnt orange
Testing for starch
Add a few drops of iodine to the sample in a spotting tile - it will turn from
yellow to blue/black if starch is present - this test is qualitative
, Polysaccharides
Amylose forms unbranched chains and amylopectin forms
branched chains (1-6 glycosidic bonds)
Starch
Made of chains of alpha glucose monosaccharides linked by glycosidic bonds
formed by condensation reactions
It is a mixture of 20% amylose and 79% amylopectin and 1% phosphates and
fatty acids
The main role of starch is energy storage and the structure is suited for
because:
It's insoluble so doesn't affect water potential so the osmosis patterns
of water are not affected
It's large and insoluble which prevents it from moving out of cells by
diffusion
It's compact so can be stored in a small space which allows for a larger
amount of energy to be stored
When hydrolysed it forms alpha glucose which is easily transported
around the plant to be used for respiration
The branched form (amylopectin) has many ends - each of which can be
acted on by enzymes simultaneously meaning that glucose monomers
are released very rapidly
Glycogen
Made up of chains of alpha glucose monosaccharides by glycosidic
bonds
It's branched like amylopectin but has more branches due to the higher
presence of 1-6 bonds and has shorter chains
Insoluble does not draw water into the cell through osmosis
Carbohydrates
Monosaccharides are the monomers from which larger carbohydrates
are made. Glucose, galactose and fructose are common
monosaccharides. A condensation reaction between two
monosaccharides forms a glycosidic bond.
Disaccharides are formed by the condensation of two
monosaccharides:
• maltose is a disaccharide formed by condensation of two glucose
molecules
• sucrose is a disaccharide formed by condensation of a glucose
molecule and a fructose molecule
• lactose is a disaccharide formed by condensation of a glucose
molecule and a galactose molecule.
Glucose has two isomers, α-glucose and β-glucose, with structures:
Polysaccharides are formed by the condensation of many glucose
units.
• Glycogen and starch are formed by the condensation of αglucose.
• Cellulose is formed by the condensation of β-glucose.
The basic structure and functions of glycogen, starch and cellulose.
The relationship of structure to function of these substances in
animal cells and plant cells. Biochemical tests using Benedict's
solution for reducing sugars and non-reducing sugars and
iodine/potassium iodide for starch.
Monosaccharides are monomers from which larger carbohydrates are made.
Common monosaccharides include glucose, fructose and galactose
A condensation reaction between two monosaccharides forms a glycosidic
bond and a disaccharide
Glucose + glucose = maltose
Glucose + fructose = sucrose
Glucose + galactose = lactose
Glucose has two isomers - alpha (α) glucose and beta (β) glucose
,The position of the hydroxyl groups on carbon 1 are inverted between
alpha and beta glucose
Polysaccharides are formed by the condensation of many glucose units
Glycogen and starch are formed from the condensation of α- glucose
Cellulose is formed from the condensation of β- glucose
Testing for reducing sugars (all mono and disaccharides but
sucrose)
Add 2cm3 of the sample to a test tube, liquidise if necessary, add an equal
amount of benedict's reagent (copper II sulphate and NaOH) , heat in a
boiling water bath for 5 minutes. The test is a semi- quantitative test so it
gradually changes colour from blue to brick red if a reducing sugar is present.
Non - reducing sugars - polysaccharides + sucrose
1. Test for reducing sugars using benedict's solution
2. If you get a negative result you try to break down the polysaccharide
3. Add 2cm3 of the sample to the same amount of HCL. Add to a boiling
water bath for 5 minutes which will hydrolyse the disaccharides into their
monosaccharides
4. Slowly add some Sodium hydrogen carbonate to neutralise the HCL and
test the Ph with the litmus paper to check
5. If a non- reducing sugar was present in the original sample, the benedict's
reagent will turn burnt orange
Testing for starch
Add a few drops of iodine to the sample in a spotting tile - it will turn from
yellow to blue/black if starch is present - this test is qualitative
, Polysaccharides
Amylose forms unbranched chains and amylopectin forms
branched chains (1-6 glycosidic bonds)
Starch
Made of chains of alpha glucose monosaccharides linked by glycosidic bonds
formed by condensation reactions
It is a mixture of 20% amylose and 79% amylopectin and 1% phosphates and
fatty acids
The main role of starch is energy storage and the structure is suited for
because:
It's insoluble so doesn't affect water potential so the osmosis patterns
of water are not affected
It's large and insoluble which prevents it from moving out of cells by
diffusion
It's compact so can be stored in a small space which allows for a larger
amount of energy to be stored
When hydrolysed it forms alpha glucose which is easily transported
around the plant to be used for respiration
The branched form (amylopectin) has many ends - each of which can be
acted on by enzymes simultaneously meaning that glucose monomers
are released very rapidly
Glycogen
Made up of chains of alpha glucose monosaccharides by glycosidic
bonds
It's branched like amylopectin but has more branches due to the higher
presence of 1-6 bonds and has shorter chains
Insoluble does not draw water into the cell through osmosis
