Biological Molecules Flashcards
What is a hydrogen bond?
A weak interaction that can occur whenever molecules contain a slightly positive charged atom bonded to a slightly negative charged atom.
What is a hydrolysis reaction?
A reaction that occurs when a molecule is split into two smaller molecules with the addition of water.
What is a monomer?
A small molecule which binds to many other identical molecules to form a polymer.
What is a polymer?
A large molecule made up of monomers.
Why is a water molecule polar?
oxygen has a greater number of positive protons in its nucleus so that it exerts a greater attraction for shared electrons making it slightly negative and the hydrogen atoms become slightly positive
Why is a hydrogen bond weaker than a covalent bond?
A hydrogen bond is a weak interaction between slightly positive and slightly negative molecules whereas covalent bonds are the sharing of electrons to gain a full outer shell.
What are carbohydrates?
A group of molecules containing carbon, hydrogen and oxygen.
What is a condensation reaction?
A reaction that occurs when two molecules join together with the removal of water.
What is a glycosidic bond?
A bond formed between two monosaccharides by a hydrolysis reaction.
What is the function of carbohydrates?
To act as a source of energy(glucose), a store of energy(starch and glycogen), and as structural units(cellulose in plants).
What are the three main groups of carbohydrates?
Monosaccharides, disaccharides and polysaccharides.
What are monosaccharides?
The simplest carbohydrates. Good source of energy because of large number a carbon to hydrogen bonds. Soluble in water and insoluble in non- polar solvents.
What are disaccharides?
Sweet and soluble.
Most common is maltose.
Give an example of a reducing sugar?
Maltose and lactose.
Give an example of a non-reducing sugar?
Sucrose.
How are disaccharides made?
When two monosaccharides join.
What makes maltose?
Alpha-glucose + alpha-glucose.
What makes sucrose?
Alpha-glucose + fructose.
What makes lactose?
Beta-galactose + alpha-glucose.
What makes cellobiose?
Beta-glucose + beta-glucose.
What happens when monosaccharides join.
A condensation reaction and a glycosidic reaction.
What does a hydrolysis reaction do?
Breaks disaccharides into monosaccharides.
What is the bond joined to the top carbon bond in glucose?
CH2OH
What is the molecular formula of sugars?
CnH2nCn
Difference between alpha glucose and beta glucose
The OH and H are swapped round
Molecular formula of Ribose
C5 H10 O5
Molecular formula of deoxyribose
C5 H10 O4
Carbohydrate monomer?
Monosaccharides- glucose
Carbohydrate polymer?
Polysaccharides- starch
Difference between alpha and beta glucose?
In Alpha glucose the H is above the OH
Difference between ribose and deoxyribose?
Ribose is bonded down to two OH’s
Molecular formula of glucose?
C6H12O6
Alpha glucose role in the body?
Energy source
Component of starch and glycogen
Energy stores
Role in the body of beta glucose?
Energy source
Component of cellulose
Role in the body of ribose?
Component of RNA and ATP
Role in the body of deoxyribose?
Component of DNA
Example of non-reducing sugar?
Sucrose
How to calculate Rf value?
Distance travelled by dye over distance travelled by solvent
What are the main polysaccharides?
Glycogen, starch and cellulose
Describe glycogen?
Compact- doesn't occupy a large space In animals Branched- 1,4 and 1,6 glycosidic bond Occur in dense granules Less soluble in water
Describe starch?
Compact
Occurs in granules within a cell
Describe amylose?
Unbranched chain Alpha glucose molecules (chain) 1/4 glycosidic bonds Spiral shape held with H bonds Less soluble
Amylopectin description?
Branched chain
More compact- hydrolysed more easily
Spiral shape held by hydrogen bonds
1,4 and 1,6 glycosidic bonds
Describe cellulose?
Found in plant cell walls
Tough, insoluble and fibrous
Made form long chains of beta glucose molecules
Chains lie straight rather than spiralling
How are the cellulose chains straight?
Hydrogen and hydroxyl groups on carbon 1 are inverted
The beta glucose molecules in the chain are rotated by 180 degrees. The beta 1,4 glycosidic bond prevent spiralling.
Describe microfibrils?
60-70 cellulose chains bonded together. 10-30 nm in diameter Bundle together to form macrofibrils Run in all directions and criss-cross Numerous hydrogen bonds between chains
Properties of cellulose?
High tensile strength
Difficult to digest
Permeable for water molecules and ions
Roles of calcium?
Bone and teeth rigidity Blood clotting and muscle contraction Activator for enzymes Regulates permeability of cell membranes Cell wall development
Functions of hydrogen?
Involved in photosynthesis and respiration
Involved in transport of co2 in the blood
Reducing sugars test?
Heat with Benedicts solution- copper sulphate
Blue- green- yellow- orange/red
Forms a precipitate
Non- reducing sugar test?
First test for reducing sugars
Separate sample- boil with hydrochloric acid
Cool and neutralise with hydrogencarbonate
Test for reducing sugar again
Green- yellow- orange- red
Apparatus to be used in qualitative tests?
Spotting tile
Calibration chart
Colorimeter
Biosensors
Test for starch?
Spotting tile
Add iodine
Yellow/brown to blue/black
