1.4 Starch, Glycogen & Cellulose Flashcards
What is starch?
Polysaccharide found in plants in the form of small grains
Are starch chains branched or unbranched?
Can be either
What is starch made up of?
Alpha-glucose monosaccharides linked by glycosidic bonds
Why is the structure of starch suited for energy storage?
- Insoluble; does not affect water potential
- Large; cannot diffuse
- Compact
- Branched form has many ends; glucose monomers released rapidly
What is the difference between starch and glycogen?
Glycogen has shorter chains & is more highly branched compared to starch
Where is glycogen stored?
As granules, in the liver and muscles
Why is the structure of glycogen suited for animal storage?
- Insoluble
- Compact
- More highly branched than starch
What is the shape of cellulose chains?
Straight, unbranched
Why do cellulose chains run parallel to one another?
H bonds can form cross-linkages between adjacent chains
What are groups of cellulose called?
Microfibrils
Why is the structure of cellulose suited to its function of providing support?
- Beta-glucose; forms long, unbranched chains
- crossed linked by H bonds; more strength
- microfibrils; more strength
Describe the test for starch
- Add iodine dissolved in potassium iodide solution
- If starch present: from browny-orange -> blue-black colour
What is amylopectin?
Long, branched chain of alpha-glucose
