Starch, Glycogen and Cellulose as Efficient Storage and Structural Compounds

621 Words2 Pages

Starch, Glycogen and Cellulose as Efficient Storage and Structural Compounds

Starch is a complex carbohydrate, it's a mixture of amylose and

amylopectin both of which are polysaccharides containing α-glucose

molecules linked via a condensation reaction.

Amylose is a long, straight chain of α-glucose molecules, these are

linked together by a 1,4 glycosidic bond, where 1 & 4 are carbon

reducing centres.

+ +…

α-glucose molecule α-glucose molecule

= + H20

amylose

These chains of α-glucose coil to form spirals and these are held in

place by hydrogen bonds.

Amylopectin, on the other hand, is a branched chain due to some of its

glucose residues joining via a 1,6 glycosidic bond, however this is

still formed by a condensation reaction.

Due to starch being made up from amylose and amylopectin which are

both polysaccharides and produced by a condensation reaction, starch

can easily be broken down when H20 is added and the -o- glycosidic

bond is broken, this process is called hydrolysis. The breaking of

this bond has a result of 2 α-glucose molecules…it's the opposite

reaction of condensation. Now being in the form of glucose it can be

used in respiration by the plant.

Also due to amylose and amylopectin both being of a compact nature, it

being a characteristic of the two, a large amount of starch can be

stored in a relatively small space. Not only that but starch is also

insoluble and therefore it won't affect water potential (ψ) in the

cells in which it's stored, therefore it won't cause water movement

across membranes and so will stay within 1 part of a plant.

All these factors contribute to ...

... middle of paper ...

...hol) on each glucose monomer the pattern in cellulose is that of

the glucose unit being 'flipped over' when compared to the glucose

prior to itself in order for the OH groups to be in the correct

position for a 1,4 glycosidic bond to form. This in turn allows two

hydrogen atoms to be side by side and as a result a strong hydrogen

bond is formed, adding to the structure of cellulose.

+ +…

β-glucose β-glucose

= + H20

Cellulose

Cellulose is an efficient structural compound due to;

· It being insoluble, so will stay rigid even when wet.

· It's very strong so can withstand opposing forces.

Overall starch, glycogen and cellulose are efficient at their jobs,

whether it's storage or structural, for several reasons all of which

have hopefully been successfully highlighted throughout this essay.

Open Document