1.4- Starch, glycogen and cellulose Flashcards
What is Starch and it’s role?
Starch is a polysaccharide that stores energy in plant- large amounts occur in seeds
What type of chains is starch made from?
alpha glucose monosaccharides linked by glycosidic bonds that are formed by condensation reactions
Are starch chains branched or unbranched?
Starch chains ,may be branched or unbranched, the unbranched chain is wound into a tight coil that makes the molecule very compact
The main role of starch is energy storage. How is starch suited for this role?
- Insoluable= doesn’t effect water potential
- Compact= a lot of energy can be stored in one space
- when hydrolyzed forms alpha glucose= alpha glucose easily transported and used in respiration
What group in starch faces inwards forming hydrogen bonds, in turn holding the helix in place?
OH groups
Name 2 key differences between structure of starch and glycogen
- glycogen has smaller chains
2.glycogen is more highly branched
How is glycogen formed?
from the condensation of alpha glucose
What is glycogen for and where is it stored?
glycogen is a major carbohydrate storage product of animals
stored in muscle and liver cells
How does the structure of glycogen suit it’s function for storage?
- insoluable= doesn’t draw water in by osmosis, does not diffuse out of cells
- compact= a lot of it can be stored in small space
3.more highly branched than starch- has more ends that can be simultaneously acted on by enzymes
therefore, more rapidly broken down to form glucose monomers, used in respiration
Why is it important that glycogen can be rapidly broken down into glucose monomers which are used in respiration?
Animals have a higher metabolic rate and therefore higher respiratory rate than plants because they are more active
What is cellulose made from?
beta glucose monomers joined by glycosidic bonds
What is different about the structure of Cellulose as oppose to Starch and Glycogen?
Cellulose has straight unbranched chains that run parallel to each other allowing hydrogen bonds to form cross- linkages between adjacent chains as opposed to a coiled chain.
What is important about these hydrogen bonds in Cellulose?
individually hydrogen bonds add little strength however together they make a large contribution to strengthening cellulose, making it a crucial structural material
Why are adjacent glucose molecules rotated by 180 degrees on a cellulose chain unlike starch?
allows hydrogen bonds to be formed between hydroxyl (-OH) groups- help give cellulose structural stability
How is cellulose important in stopping the cell burst under osmotic pressure?
exerts inward pressure that stops influx of water - means the cells stay turgid and rigid– helping maximize the surface area of plants for photosynthesis
