Starch, Glycogen and Cellulose Flashcards
What is starch
A polysaccharide that is found in many parts of a plant in the form of small grains.
What’s starch made up of
Alpha glucose monosaccharides linked by glycosidic bonds that are formed by condensation reactions
What’s the chains like in starch
Can be branched or unbranched
What makes starch so compact
The unbranched chain is wound into a tight coil that makes the molecule very compact
What’s the main role of starch
Energy storage
How is starch suited to its structure
Insoluble - doesn’t affect water potential, so water is not drawn into the cells by osmosis
Large and insoluble- does not diffuse out of cells
Compact- a lot can be stored in a small space
When hydrolysed - forms alpha glucose, which is both easily transported and readily used in respiration
Branched ( has many ends) - each can be acted on by enzymes simultaneously meaning that glucose monomers are released very rapidly
What’s glycogen
Similar to starch but it has shorter chains and is more highly branched.
It is the major carbohydrate storage product of animals
How does glycogen structure suit storage
Insoluble - does not tend to draw water into the cells by osmosis
Insoluble- does not diffuse into cells
Compact - a lot can be stored in a small space
Highly branched - has more ends that can be acted on simultaneously by enzymes. More rapidly broken down to form glucose monomers, which are used in respiration
What monomers is cellulose made of
Beta glucose
What’s the structure like in cellulose
Unlike a coiled chain like starch. Cellulose has straight unbranched chains. Linked with H bonds between chains.
What do the H bonds do to the structure in cellulose
The sheer overall number of them makes a considerable contribution to the strengthening cellulose
What are cellulose molecules grouped together to form
Microfibrils
What is celluloses job
Provides rigidity in the plant cell ( major component in plant cell wall)
Cellulose wall prevents the cell from bursting as water enters it by osmosis- does this by exerting an inward pressure that stops any further influx of water - living plants cells are turgid and push against one another, making non woody parts of the plant semi rigid
Important so they can provide maximum surface area for photosynthesis
How is the cellulose suited to its function of providing support and rigidity
Cellulose molecules are made up of Beta glucose - so form long straight unbranched chains
Cellulose molecular chains run parallel to each other - cross linked by H bonds which add collective strength
They are grouped to form microfibrils- which is turn are grouped to form fibres all of which provides get more strength
What’s amylopectin in starch
a long, branched chain of alpha gluocose. its die branches allow the enzymes that break down the molecule to get at the glycosidic bonds easily. this means that the glucose can be released quickly
