Monosaccharide and Disaccharide Flashcards
(24 cards)
Role of carbohydrates
- energy source e.g.. glucose
- energy storage such as starch
- structural e.g. cellulose
Elements in carbohydrates and ratio
Carbon, Hydrogen and Oxygen
C:H:O
1:2:1
What is a monosaccharide?
A simple sugar unit
What is a Disaccharide ?
Two monosaccharides linked together
What is a polysaccharide?
Many monosaccharides linked together
(min of 3)
What is a monomer?
A small, basic molecular units eg. monosaccharides, amino acids, nucleic acids
What is a polymer?
Large, complex molecules composed of long chains of monomers joined together e.g. cellulose, starch and proteins
What is a hexose monosaccharide and example
6 carbon molecule
glucose
glucose chemical formula
C₆H₁₂O₆
Two forms of glucose
Alpha (α) and beta (β)
Draw a glucose monomer with labelled carbons
Look it up
What is the difference between alpha and beta glucose
Alpha glucose as the OH group below C1
Beta glucose has the OH group above C1
Fructose
- hexose sugar
- main sugar in fruits and nectar
- very soluble
- sweeter than glucose
Galactose
Hexose sugar
Not as soluble as fructose, used in production of glycolipids and glycoprotiens
Not as sweet as glucose
What are pentose monosaccharides and 2 examples
monosacchardies that contain 5 carbon atoms
ribose and deoxyribose
Draw ribsoe and deoxyribose
Look it up
Difference between ribose and deoxyribose
Ribose- OH group below C2
Deoxyribsoe-H below C2
How are disaccharides formed
When two alpha glucose molecules are side by side, the two hydroxyl groups react. When this happens bonds are broken and new bonds are formed, making new molecules.
When 2 alpha glucose are next to each other the C1 is closest to the C4 of the other glucose. The two OH groups form a glycosidic bond. H₂O is released. Called a condensation reaction.
Draw a disaccharide reaction between two alpha glucose
look up answer
What is the bond formed between the OH groups in a disaccharide between 2 alpha glucose
α 1-4 glycosidic bond
α Lactose
Found in milk
Formed by beta galactose and alpha glucose
Bond is a β1-4 glycosidic bond.
Recognisable because the bond is formed upwards
β Lactose
Formed from β galactose and β glucose. Bond formed is a β 1-4 glycosidic bond.
Beta bond is directed upwards
Sucrose
Formed by the joining of glucose and fructose. Bond formed is a α1 β2 glycosidic bond.
3 disaccharides and formation
maltose: made up of 2 glucose molecules
Lactose: Made up of glucose and galactose
Sucrose: made up of glucose and fructose.
