Carbohydrates and Lipids Flashcards
What is a monomer?
Smaller units from which larger molecules are made.
What is a polymer?
Molecules made from a large number of monomers joined together.
Name some monomers?
Monosaccharides, amino acids, nucleotides.
What is a condensation reaction?
A reaction that joins two molecules together with the formation of a chemical bond, involving the elimination of a molecule of water.
What is a hydrolysis reaction?
A reaction that breaks a chemical bond between two molecules, involving the use of a molecule of water.
What is a monosaccharide?
The monomer from which larger carbohydrates are made.
Name some monosaccharides?
Glucose, fructose, galactose.
How are disaccharides formed?
They are formed in a condensation reaction between two monosaccharides, forming a glycosidic bond and releasing a molecule of water.
Name some examples of disaccharides?
glucose + glucose = maltose
glucose + fructose = sucrose
glucose + galactose = lactose
What is an isomer?
Molecules with the same molecular formula but the atoms are arranged in a different way.
What are the two isomers of glucose?
Alpha glucose - hydroxyls on same side
Beta glucose - hydroxyls on opposite sides
What is the test for reducing sugars?
Benedict’s reagent test
- Add Benedict’s reagent to sample and heat in a water bath at 60°C
- If a reducing sugar is present there will be a colour change from blue to brick red (as ppt forms)
Explain the results of the Benedict’s reagents test?
Benedict’s reagent is made out of CuSO4 so contains Cu2+ ions. Reducing sugars can donate an electron to Cu2+, which turns into Cu+. Cu+ is a brick red precipitate.
Name some examples of reducing sugars?
All monosaccharides and some disaccharides e.g. maltose.
What is the test for non-reducing sugars?
- Add dilute hydrochloric acid to the sample and heat in a water bath at 60°C
- Add sodium hydrogen carbonate to neutralise sample
- Add Benedict’s reagent to sample and heat in a water bath at 60°C
- If a reducing sugar is present there will be a colour change from blue to brick red (as ppt forms)
What is a polysaccharide?
Molecules in a condensation reaction of many glucose units.
Name some examples of polysaccharides?
Glycogen, starch and cellulose
Describe the structure of glycogen?
It is made up of alpha-glucose monomers. It is a very branched structure as 1,4 and 1,6 glycosidic bonds are present. It also has many side branches.
Where is glycogen found?
In animal and fungal cells. There are high concentrations in liver and muscles cells due to their high metabolic demands.
What is the function of glycogen?
It is the main storage of excess glucose in animal and fungal cells. It is needed as glucose is soluble, so if this was stored in cells instead of glycogen, it would cause water to move into cells by osmosis, causing them to burst.
How does the structure of glycogen aid its function?
Glycogen being very branched allows for rapid hydrolysis to provide cells with glucose for respiration faster. Having a branched structure also means glycogen is compact. Glycogen is insoluble in water to prevent any osmotic water uptake that would cause the cell to burst/ it is very large so does not leave cells by diffusion.
Describe the structure of starch?
Starch is made out of two polysaccharides - amylose and amylopectin.
Describe the structure of amylopectin?
It is made up of alpha-glucose monomers. It is a branched structure as 1,4 and 1,6 glycosidic bonds are present. It is less branched than glycogen, however.
Describe the structure of amylose?
It is made out of alpha-glucose monomers. It is an unbranched helical structure as only 1,4 glycosidic bonds are present.
