3.1 Biological Molecules Flashcards
What is a monomer?
Monomers are the smaller units from which larger molecules are
made. Monosaccharides, amino acids and nucleotides are examples of
monomers.
What is a polymer?
Polymers are molecules made from a large number of monomers
joined together
What is a condensation reaction?
A condensation reaction joins two molecules together with the
formation of a chemical bond and involves the elimination of a
molecule of water.
What is a hydrolysis reaction?
A hydrolysis reaction breaks a chemical bond between two
molecules and involves the use of a water molecule.
Why is the biochemical basis of life similar for all living things?
The cells of all living organisms contain only a few groups of carbon based compounds that interact in similar ways.
What are monosaccharides and three examples of them?
Monosaccharides are the monomers from which larger
carbohydrates are made. Glucose, galactose and fructose are
common monosaccharides.
In what reaction do monosaccharides join and what bond is formed?
A condensation reaction between two monosaccharides forms a
glycosidic bond.
How are disaccharides formed and what are three examples of them?
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.
What are the two isomers of glucose and their structures?
α-glucose and β-glucose
How are polysaccharides formed and what are three examples of them?
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
What is the basic structure and function of glycogen?
Animal cells store excess glucose as glycogen. Glycogen is a polysaccharide of alpha-glucose. Highly branched - means glucose can be released quickly as more enzymes can act on it. Animals have a higher metabolic rate than plants so require more energy. Very compact - good for storage. Insoluble - does not affect water potential and doesn’t diffuse out of the cell.
What is the basic structure and function of starch?
Plant cells store excess glucose as starch. It’s a mixture of two polysaccharides of alpha glucose (amylose and amylopectin). *Amylose- unbranched chain, coiled structure makes it compact which is good for storage
*Amylopectin- branched chain, side branches allow enzymes to get to glycosidic bonds easily so glucose can be released quickly.
Insoluble- does not affect water potential. Large molecule- does not diffuse out of the cell
What is the basic structure and function of cellulose?
Long, unbranched chains of beta-glucose.
Form straight chains. Chains link together by hydrogen bonds to form microfibrils. This means cellulose provides structural support to cells - in plant cell walls.
How do you test for reducing sugars?
Reducing sugars include all monosaccharides and some disaccharides.
1) Add benedicts reagent (blue) to sample
2) Heat in a water bath that’s been brought to boil
3) If test positive it will form a green/yellow/orange/brick red precipitate.
Concentration of reducing sugars can be compared with colour change. More accurate way is to filter the solution and weigh the precipitate.
How do you test for non-reducing sugars?
If test for reducing sugar is negative, you have to break them down into monosaccharides.
1) Add dilute hydrochloric acid to new sample and heat in water bath
2) Neutralise it with sodium hydeogencarbonate
3) Carry out benedict’s test
4) If positive it will form coloured precipitate
