Starch, Glycogen and Cellulose Flashcards
What is Starch?
A polysaccharide found in plants in the form of small grains.
Where do large amounts of Starch occur?
Seeds and storage organs, such as potato tubers.
Why is Starch important?
It is an important component of food and is the major energy source in most diets.
What is Starch made from?
Chains of a-glucose monosaccharides linked by glycosidic bonds. Chains are unbranched or branched.
How does the structure of Starch relate to its function?
- insoluble so doesn’t effect water potential.
- large and insoluble so doesn’t diffuse out of cells.
- unbranched form is compact, can be stored in small space.
- a-glucose (hydrolysed), easily transported and readily used in respiration.
- branched form has many ends for enzymes to act on simultaneously meaning glucose monomers can be rapidly released.
What is Glycogen?
Known as the animal starch as it is a major carbohydrate storage product of animals.
What is the structure of Glycogen?
shorter chains and more highly branched than starch.
stored in small granules in the muscles and liver.
Why is the mass of carbohydrate stored in animals relatively small?
Fat is the main storage molecule In animals.
How does the structure of glycogen relate to its function?
- Insoluble so doesn’t draw water into cells by osmosis.
- Does not diffuse out of cells due to insolubility.
- Compact so a lot can be stored in one space.
- Highly branched so more enzymes act on simultaneously. Broken down into glucose monomers which are rapidly used in respiration.
Why is it important that glycogen is more highly branched?
Animals have a higher metabolic rate and therefore respiratory rate than plants because they are more active.
What is Cellulose?
Made of monomers of B-glucose. Straight unbranched chains, running parallel to each other.
What is the structure of Cellulose?
Rather than coiling like Starch, made up of straight unbranched chains that run parallel, allowing hydrogen bonds to form cross-link.
Why are hydrogen bonds between chains of Cellulose significant?
Overall strength of hydrogen bonds strengthens cellulose, making it the valuable structural material that it is.
What do groups cellulose molecules create?
Grouped cellulose molecules form micro fibrils which are arranged in parallel groups called fibres.
What is the role of Cellulose in plant cells?
Cellulose is a major component of plant cell walls, providing rigidity to plant cell. It prevents cell from bursting as water enters by exerting inward pressure to prevent influx of water.
