Biological Molecules - Starch, Cellulose And Glycogen Flashcards
(26 cards)
Give 3 examples of polysaccharides
Starch, glycogen and cellulose
Where is starch mostly found?
In seeds and storage organs such as a potato tuber
Which monosaccharide forms Starch?
Alpha glucose
Why is starch an insoluble polysaccharides?
So it does not affect the water potential of the plant and cause water movement
What bonds are unbranched chains of starch made up of?
1,4 glycosidic bonds
What bonds are branched molecules of starch made up of?
1,4 and 1,6. Glycosidic bonds
What do unbranched chains of starch form and why?
They form tight coils (helices) which make it compact - good for storage
Why is starch a good storage molecule? (5 reasons)
- Insoluble - doesn’t affect water potential
- Compact - a lot stored in small space
- Large and insoluble - doesn’t diffuse out of cells
- Hydrolysed to form alpha glucose - used in respiration
- Branched form (amylopectin) has many ends- provides large surface area for enzymes to act upon
Which form of starch is branched? Amylose or amylopectin
Amylopectin
Why does amylose ( unbranched) coil in on itself?
The OH’s in the alpha glucose all point inwards and therefore form hydrogen bonds to hold the helix in place
Amylopectin - why is it branched?
They have both 1,4 and 1,6 glycosidic bonds
What test is used to test for starch and what is the result?
Iodine test, orange to blue black
What is glycogen made up of?
Alpha glucose molecules
Why is it useful for animals that glycogen is more highly branched than starch?
There is a higher surface area for rapid release of energy which is important for animals as they have a higher metabolic rate
Give three propertied of glycogen
Highly branched
Compact
Insoluble
Where is glycogen found and in what form?
Granular form, liver cells, muscles, kidneys, brain etc
What type of polysaccharide is cellulose?
A structural polysaccharides
What monomer makes up cellulose?
Beta glucose
How does beta glucose affect cellulose structure?
Makes the chains of beta glucose long and straight
What is formed between the long straight chains of cellulose?
Cross linkages of hydrogen bonds
what causes cellulose to be strong
The cross linkages of hydrogen bonds
What happens to every other beta glucose molecule when a chain is formed?
They are rotated 180°
What does cellulose molecules group together to form?
Microfibrils
What are microfibrils arranged into?
Fibres
