2406131
Description
Flashcards by Charlotte Hewson, updated more than 1 year ago
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Created by Charlotte Hewson
over 10 years ago
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| Question | Answer |
| what is starch? | A polysaccharide |
| where is it found? | many parts of plants |
| what is it found in the form of? | small grains |
| where can large amounts be found? | seeds and storage organs eg potato tubers |
| what is starch made up of? | chains of alpha-glucose monosaccharides |
| how are these monosaccharides linked? | glycosidic bonds |
| how are these bonds formed? | condensation reactions |
| how is the molecule compact? | it winds into a tight coil |
| what colour does it stain with iodene solution? | deep blue |
| what is the main role of starch? | energy storage |
| how is it suited for this? | -insoluble -compact -can be hydrolysed |
| why does it help to be insoluble? | -doesnt draw water into cells by osmosis -doesnt easily diffuse out of cells |
| why does it help to be compact? | it can be stored in small spaces |
| why does it help to be hydrolysed? | when hydrolised, it forms alpha-glucose which is easily transported and readily used in respiration |
| where is starch never found? | animal cells |
| which polysaccharide serves the same role but in humans? | glycogen |
| how is glycogen similar to starch? | similar structure |
| what are the two differences in its structure? | shorter chains and highly branched |
| how and where is it stored? | -as small granules -mainly in the muscles and liver |
| why does it help to be made up of smaller chains? | can be hydrolysed more rapidly to alpha-glucose |
| where is glycogen never found? | plant cells |
| how does cellulose deffr from starch and glycogen? | its made of monomers of beta-glucose |
| how does the arrangement of a beta-glucose unit differ to an alpha-glucose? | the position of the -H group and the -OH group opn a single carbon atom are reversed |
| how is a beta-glucose arranged? | the -OH group is above the ring |
| how do you then get glycosidic links? | each molecule must be rotated 180 degrees compared to its neighbour |
| what is the result of this rotation? | the --CH(2)OH group on each beta-glucose molecule alternates between being above and below the chain |
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