carbohydrates

Question 1

draw the structure of a-glucose and B-glucose

Answer 1

• (refer to images)
• both hexose monosaccharides (6 carbon) with a ring structure
• only difference is one H-OH is flipped on beta glucose resulting in a OH-H instead

Question 2

describe the properties of a-glucose

Answer 2

• small and water soluble so is easily transported in the bloodstrean
• complementary shape to antiport for co-transport for absorption in the gut
• complementary shape to enzymes for glycolysis = respiratory substrate

Question 3

draw the structure of ribose

Answer 3

• (refer to images)
• pentose monosaccharide (5 carbon)
• ring structure

Question 4

what type of bond forms when monosaccharides react?

Answer 4

• 1-4 or 1-6 glycosidic bond
• 2 monomers = 1 chemical bond = disaccharide
• multiple monomers = many chemical bonds = polysaccharide

Question 5

name 3 disaccharides and describe how they form

Answer 5

• a condensation reaction takes place, forming a glycosidic bond between 2 monosaccharides
• maltose: formed from glucose + glucose
• sucrose: formed from glucose + fructose
• lactose: formed from glucose + galactose
• all 3 examples have the molecular formula C12H22O11

Question 6

describe the structure and functions of starch

Answer 6

• made from both amylose: 1-4 glycosidic bonds, helix with intermolecular H-bonds = compact - and amylopectin: 1-4 and 1-6 glycosidic bonds, branched with many terminal ends = for hydrolysis into glucose
• storage polymer of a-glucose in plant cells
• insoluble: no osmotic effect on cells
• large: does not diffuse out of cells

Question 7

describe the structure and functions of glycogen

Answer 7

• 1-4 and 1-6 glycosidic bonds
• branched with many terminal ends = hydrolysis
• insoluble: no osmotic effect and doesn’t diffuse out of cells
• compact
• main storage polymer of a-glucose in animal cells (but can also be found in plant cells)

Question 8

describe the structure and function of cellulose

Answer 8

• 1-4 glycosidic bonds
• straight chain, unbranched molecule
• alternate glucose molecules are rotated 180°
• H-bonds crosslinks between parallel strands form microfibrils = high tensile strength
• polymer of B-glucose, gives rigidity to plant cell walls = prevents bursting under turgor pressure, holds stems up