Carbohydrates Flashcards
What are all biological molecules built from?
Monomers
When two sun-units join together what is formed?
A dimer
When many sub-units join together what is formed?
A polysaccharide
Monosaccharides are the monomers of what?
Carbohydrates
Monosaccharides are single what units?
Single sugar units with the general formula (CH2O)n
What can these single sugar units be called?
Hexose sugars (because 6 is the most common number of carbon atoms)
What are the three important monosaccharides?
Glucose, galactose and fructose
Are monosaccharides soluble or insoluble? Why?
Soluble because they can form hydrogen bonds with water as they contain OH and H atoms
What is the main sugar used by all cells in respiration?
Glucose
Which polymers are made of glucose?
Starch and glycogen
What happens when starch or glycogen is digested?
Glucose is produced which can be easily absorbed and transported in the bloodstream to cells
What is galactose mainly in our diet as?
Part of the disaccharide sugar lactose
Which -OH groups are on the opposite side to glucose?
The -OH groups on carbon one and four
Where does fructose occur naturally?
In fruit, honey and some vegetables
What do monosaccharides provide? Why?
A rapid source of energy because they are readily absorbed and require little/no change before being used in cellular respiration
What reactions form disaccharides?
Condensation reactions
What molecule is released as two sugar molecules combine in a condensation reaction?
A water molecule
What bond is formed in the formation of a disaccharide?
A glycosidic bond
What are the three important disaccharides?
Maltose, sucrose and lactose
How are disaccharides split?
By hydrolysis reactions (where water is added to the glycosidic bond)
What two monosaccharides join to make maltose?
Glucose and glucose
When is maltose produced?
When amylase breaks down starch
What two monosaccharides join to make sucrose?
Glucose and fructose
What is the usual form in which sugar is transported around a plant?
Sucrose
What two monosaccharides join to make lactose?
Galactose and glucose
Which sugar is found in milk?
Lactose
What are polysaccharides composed of?
Single sugar monomers (monosaccharides)
What bond holds together polysaccharides?
Glycosidic bonds
Are polysaccharides short or long chained structures?
Long chained structures
Are polysaccharides soluble in water and sweet?
No, they are not very soluble in water and have a bitter taste
What are the three main polysaccharides found in food?
Glycogen, cellulose and starch
Who stores glycogen?
Animals
Where is glycogen stored in humans?
In the liver and muscles
Why can glycogen be rapidly hydrolysed?
Because it has numerous side branches, giving easy access to stored energy
What contains cellulose and stores starch?
Plants
What is Cellulose also known as?
Dietary fibre
What is celluloses basic structure?
A straight chain
What two polymers is starch formed of?
Amylose and amylopectin
Which polymer has a straight chain of between 200-5000 molecules and contains 1,4 glycosidic bonds
Amylose
What is the structure of amylopectin?
Amylopectin has side branches off its main chain, it also has 1,6 glycosidic bonds
What does the position of the 1,4 glycosidic bonds cause?
The amylose chain to coil
What do both glycogen and starch act as?
Storage molecules within cells
Why are glycogen and starch suitable storage molecules?
Because the polysaccharide chains are compact with low solubility in water. This means they don’t affect the concentration of water in they cytoplasm and so don’t affect movement of water by osmosis
