Biological Molecules - Carbohydrates

Question 1

What is carbohydrate?

Answer 1

Substance whose molecules are made of sugar(saccharide) units
make up 10% organic matter in body
- Include sugar (soluble in water and sweet), starch and cellulose (insoluble in water and does not taste sweet)
- Basic structure is the same – includes carbon, hydrogen and oxygen – general formula: CnH2nOn
- Monosaccharides = REDUCING SUGARS

Question 2

difference between monosaccharides, disaccharides and polysaccharides

Answer 2

Monosaccharides
- Single sugar units
- E.g. glucose, fructose
Disaccharides
- Double sugars
- E.g. sucrose, maltose, lactose
Polysaccharides
- Many sugar units joined together
- E.g. starch, glycogen, cellulose
- Cellulose = lots of beta glucose joined together

Question 3

Monosaccharides

Answer 3

Glucose = the main respiratory substrate in cells, providing energy when oxidised
Fructose = often founds in fruits and nectar – attracts insects and other animals, which may inadvertently disperse seeds or transfer pollen
Names of sugars – triose (n=3 ), pentose (n=5 e.g. ribose), hexose (n=6 e.g. glucose and fructose) {n = number of carbons in molecule}
Monosaccharides have structural formulas e.g. chain or ring structure

Question 4

Disaccharide

Answer 4

• MONOSACCHARIDES can link together to form a sugar called a DISACCHARIDE
• 2 alpha glucose molecules form maltose
• The reaction that takes place + a condensation reaction –> reverse = hydrolysis
• BOND FORMED = GLYCOSIDIC BOND (contains covalent bonds)
• Soluble in water
• Taste sweet
• General formula = (C6H10O5)n