carbohydrates, chapter 3

Question 1

what bond joins monosaccharides together?

Answer 1

glycosidic bond

Question 2

what is glycogen and what is starch?

Answer 2

glycogen and starch are carbohydrate storages, glycogen is stored in animals and starch is stored in plants.

Question 3

features of starch

Answer 3

• made up of 2 slightly different polysaccharides

amylose : made up of alpha glucose, 1 - 4 glycosidic bonds, has a helical structure making it compact.

amylopectin : made up of alpha glucose, highly branched molecule, 1 to 6 glycosidic bonds forming branches, 1 to 4 glycosidic bonds, more insoluble than amylose.

Question 4

features of glycogen

Answer 4

• made up of alpha glucose
• more branches than amylopectin so more compact
• 1 to 4 and 1 to 6 glycosidic bonds
• insoluble in water

Question 5

why do carbohydrates have to be insoluble, branched and compact?

Answer 5

• They have to be soluble so they don’t affect the water potential of the cell
• they have to be branched so they can be broken down to glucose quickly
• they have to be compact so they don’t take up a lot of space in the cell

Question 6

features of cellulose

Answer 6

• polymer of beta glucose
• every other monomer (monosaccharide) is inverted
• because the monomers are inverted, they form straight chains that run parallel with many hydrogen bonds.
• this forms microfibrils which are very strong.
• being fibers, cellulose is structurally important in cell walls.

Question 7

most soluble to least soluble carbohydrates

Answer 7

glucose, ribose, amylose, amylopectin

Question 8

benedicts test for reducing sugars

Answer 8

• place the sample to be tested in a boiling tube. If it is not in liquid form, grind it up or blend in water
• add an equal amount of benedicts reagent
• heat the mixture gently in a boiling water bath for five minutes
• reducing sugars will react with the copper ions in the benedicts reagent. This results to the liquid turning red indicating a positive result.