Starch, Glycogen and Cellulose Flashcards
Where is starch found and in what form?
Starch is found in plants, in the form of small granules or grains
Why is starch important?
Starch is an important component in food and is a major energy source in most diets
What is starch made from?
Starch is made formed from two glucose polymers, amylose and amylopectin. Fundamentally formed from alpha glucose
What is amylose?
Amylose is a glucose polymer formed from alpha glucose monomers, consisting of 1,4 glycosidic bonds
Describe amylose’s structure
Amylose has an unbranched shape that forms a helical structure
How does amylose’s structure help with its functions?
Amylose’s unbranched helical structure allows starch to store a lot of glucose in a small space
What is amylopectin?
Amylopectin is a glucose polymer consisting of (1,4) and (1,6) glycosidic bonds
Describe amylopectin’s structure
Amylopectin has a branched structure consisting of (1,4) and (1,6) glycosidic bonds
How does amylopectins structure help with its function?
Amylopectin has a branched structure that increases its surface area and allows for rapid hydrolysis of starch into glucose
Glucose is converted into starch for storage within plant cells
Describe the reaction that occurs for this to happen
The reaction that occurs is a condensation reaction. This involves glucose molecules forming (1,4) and (1,6) glycosidic bonds with each other. With this there is an elimination of water molecules at the end of the chemical reactions
What is starch composed of that affects its structure and how does this structure help with starch’s function?
Starch is composed of amylose and amylopectin.
The helical shape of amylose makes starch more compact allowing it to fit a lot of glucose in a small space.
The branched structure of amylopectin increases the surface area and allows for rapid hydrolysis of starch to glucose for use in plant cells
How much amylose and amylopectin make up starch (percentages)?
Amylose makes up to 10-30% of starch
Amylopectin makes up to 70-90% of starch
Starch is a carbohydrate often stored in plant cells. Describe and explain two features of starch that make it a good storage molecule
- Starch is an insoluble molecule so it doesn’t affect water potential
- Starch has a helical structure making it more compact so it can fit many molecules into a small area
What is glycogen formed from? How is glycogen formed?
Glycogen is made from alpha glucose molecules. The alpha glucose molecules join together through multiple condensatio reactions. This results in (1,4) and (1,6) gylcosidic bonds forming, with the elimination of a water molecule each time.
Describe glycogen’s structure
Glycogen has a highly branched structure, even more branched than amylopectin
How does glycogen’s structure help with its function? Why is its structure important in animals?
Glycogen’s highly branched structure allows for rapid hydrolysis of glycogen into glucose. This is important for animals as they move a lot and require more energy
Where is glycogen found?
Glycogen is found in animal cells, mainly in the muscles/liver
What is glycogens main function?
Glycogen’s main function is to store glucose
What is cellulose?
Cellulose is a beta glucose polysaccharide. Consisting of long chains of beta glucose joined by (1,4) glycosidic bonds
How does cellulose form its glycosidic bonds between its beta glucose monomers?
Cellulose forms its glycosidic bonds between the beta glucose monomers through multiple condensation reactions. The beta glucose monomers must be rotated 180 degrees opposite to each other, prior to these reactions
Where is cellulose found?
Cellulose is found in plants cells, specifically their cell walls
Describe cellulose’s structure
Cellulose is composed of beta glucose monomers which form long, straight chains which are held in parallel to each other by hydrogen bonds forming fibrils
Why are beta glucose molecules rotated to 180 degrees to each other in cellulose?
The beta glucose molecules must be rotated at 180 degrees relative to each other so the glycosidic bonds can form
Glycogen and cellulose are both carbohydrates. Describe two differences between the structure of a cellulose molecule and glycogen molecule
- Cellulose is made up of beta glucose molecules and glycogen is made from alpha glucose molecules
- Cellulose has long straight chains and glycogen has a branched structure
- Glycogen has (1,4) and (1,6) glycosidic bonds and cellulose only has (1,4) glycosidic bonds
How does cellulose structure help with its functions?
Cellulose has long chains that are held in parallel to each other by their hydrogen bonds providing strength for their cell wall
Starch and cellulose are two important plant polysaccharides
Explain the difference in structure of the starch molecule and the cellulose molecule
- Starch has a helical structure whereas cellulose has long, straight chains forming its structure
- Starch is composed of (1,4) and (1,6) glycosidic bonds whereas cellulose is composed of just (1,4) glycosidic bonds
