carbohydrates Flashcards
(22 cards)
what are monosaccharides?
Single units of a sugar molecule for example glucose
What is the difference in structures between beta glucose and alpha glucose?
The OH is below the ring in alpha molecules but above the ring in beta molecules
Why is it important to form disaccharides and polysaccharides?
By bonding monosaccharides together, we are able to make the sugar more suitable for transport and storage as well as ensuring that it doesn’t impact the osmolarity of the cell.
how are disaccharides and polysaccharides formed?
They are formed when two hydroxyl groups interact to form a strong covalent bond - a glycosidic bond
What reaction is involved in the process of forming glycosidic bonds?
A condensation reaction
How is a glycosidic bond broken?
By adding water to the molecule during a hydrolysis reaction.
What are polysaccharides?
Macromolecules that are formed by many monosaccharides bonded together by glycosidic bonds in a condensation reaction to form chains.
What are some of the characteristics of the chains that polysaccharides have?
The chains can be branched or unbranched, folded making the molecule more compact and ideal for storage, straight making the molecule suitable for constructing cellular structures
What is starch?
The storage polysaccharides of plants
What are the two different polysaccharides that starch is constructed from?
Amylose (10-30%) and amylopectin (70-90%)
What is the structure of amylose?
Amylose has an unbranched helix shaped chain with a 1,4 alpha glucose glycosidic bond. The helix shape makes it more compact and resistant to digestion.
What is the structure of Amylopectin?
Has a 1,4 alpha glucose glycosidic bond as well as a 1,6 alpha glucose glysocidic bond, forming branches. This causes many terminal glucose molecules to be easily hydrolysed during cellular respiration or added to for storage.
What is glycogen?
The storage polysaccharide of animals and fungi and is highly branched and coiled.
Why do liver and muscle cells have a high concentration of glycogen?
The respiration rate are relatively high in liver and muscle cells
Why is the branching on glycogen important?
enables more free ends so glucose molecules can be added or removed more rapidly - thus the storage or release of glucose can suit the demand of the cell
What is the structure of cellulose?
A polymer consisting of long chains of beta-glucose joined by a 1,4 glycosidic bond
How are cellulose molecules bonded?
The molecules need to be rotated by 180 degrees to each other due to the inversion of the beta glucose molecules
What gives cellulose its strength?
The many hydrogen bonds that form between the long chain of cellulose molecules
Where is cellulose found and why?
Cellulose is found in a plants cell wall because of its strength which is caused by the amount of hydrogen bonds found between the parallel chains of microfibrils
Why are plant cell walls strong?
The mixture of cellulose fibres and other molecules like lignin that are inside the cell wall, forms a matrix which increases the strength of the cell wall
How does the strengthened cell walls impact the plant?
It provides support to the plant as the cellulose fibres are freely permeable which allows water and solutes to exit or reach the cell surface membrane
Why is cellulose a source of fibre?
Very few organisms have the enzyme cellulase to hydrolyse cellulose
