Monosaccharides, disaccharides and polysaccharides Flashcards
What are monosaccharides?
They are monomers of carbohydrate (simple carbohydrates).
They are sugars.
3C - triose eg. glyceraldehyde
5C - pentose eg. ribosomes
6C - hexose eg. glucose.
Features of glucose?
It is made up of 6 carbons in a ring structure.
Carbons 1-5 make up the ring whilst C6 sticks out
There is alpha and beta glucose.
Alpha glucose has the H above and the OH below
Beta glucose has the H below and the OH above
What is the function of monosaccharides?
They are an energy store in most animals and plants because they are soluble and so are easily transported and also have many covalent bonds to store lots of energy.
The covalent bonds are broken down by respiration to release energy which is stored within the bonds.
Condensation reactions can make bigger carbohydrates
Also form long structural fibres.
What is a glycosidic bond
It is when two Hydroxyl (OH) groups on two different monosaccharides interact to form a strong covalent bond known as a glycosidic bond. There are 1,4 and 1,6 glycosidic bonds and depends on which carbons the OH is found. They both release one water molecule and therefore is a condensation reaction.
a-glucose + a-glucose = ? (what type of glycosidic bond)?
Maltose (disaccharide) 1,4
a-glucose + fructose = ? (what type of glycosidic bond)?
Sucrose (disaccharide) 1,2
a-glucose + galactose = ? (what type of glycosidic bond)?
Lactose (disaccharide) 1,4
many a-glucose monosaccharides with 1,4 and 1,6 glycosidic bonds form?
Amylopectin (a form of starch)
How do you break glycosidic bonds?
Hydrolysis
What is a disaccharide?
Two monosaccharides joined together using glycosidic bond by condensation reaction which releases one water molecule.
Functions of disaccharides?
They provide quick-release energy for the body because it is two sugar molecules which can easily be broken down by enzymes into their respective monosaccharides and then absorbed into the bloodstream.
Due to the large number of OH groups they are very soluble in aqueous solutions and the OH forms hydrogen bonds with H2O.
They are sweet in taste.
What is the structure of a polysaccharide?
They are made of repeated chains of many monosaccharides, a polymer of carbohydrates.
They can be branched or unbranched, the more branched they are the easier they can be broken down.
Straight is suitable for cellular structures such as cellulose.
Coiled structures are suitable for storage since they are compact such as amylose in starch
What is starch?
It is the storage polysaccharide of plants. It is stored as granules.
It is made during photosynthesis using glucose.
Can be used to form amylose which is an unbranched helix structure due to the 1,4 glycosidic bonds and this makes it more compact and a better storage molecule.
OR
Amylopectin - 1,4 and 1,6 glycosidic bonds - branched linear structure and can be easily hydrolysed for cellular respiration
What is glycogen?
A storage polysaccharide for animals and fungi. Highly branched and not coiled, more branched than amylopectin so quicker hydrolysis, 1,4 and 1,6 glycosidic bonds made of alpha glucose
