carbohydrates

Question 1

carbohydrates functions

Answer 1

• respiratory substrate in cells
• structural components in plasma membranes and cell walls

Question 2

monosaccharides

Answer 2

• single sugar
• glucose, fructose, galactose

Question 3

alpha glucose and beta glucose difference

Answer 3

alpha - OH is in the bottom
beta - OH is on the top

Question 4

alpha and beta glucose

Answer 4

• isomers
• same atoms but arranged differently

Question 5

monosaccharides functions

Answer 5

they can be used as respiratory substrates to produce energy for reactions within the body

Question 6

polysaccharides functions

Answer 6

used as energy storage (glycogen and starch) or build structure (cellulose in cell wall)

Question 7

disaccharides

Answer 7

• two monosaccharides will bond together through a condensation reaction where a bond is formed and a molecule of water is released
• a glycosidic bond is formed

Question 8

disaccharides examples

Answer 8

glucose + glucose = maltose
glucose + fructose = sucrose
glucose + galactose = lactose

Question 9

(1,4) glycosidic bond

Answer 9

• carbon 1 is bonded to carbon 4 on the two molecules
• this is the bond in straight chain polysaccharides

Question 10

branching

Answer 10

• these are parts of the polysaccharide that branch off the main polysaccharide chain
• the bond which cause branching are (1,6) glycosidic bonds

Question 11

polysaccharides

Answer 11

a long chain of monosaccharides

Question 12

3 main polysaccharides

Answer 12

• glycogen
• cellulose
• starch

Question 13

glycogen function

Answer 13

used as an energy stored molecule in animals

Question 14

glycogen - location

Answer 14

found in the liver and muscle cells

Question 15

glycogen - structure

Answer 15

• made out of a long chain of alpha glucose
• branched, helps it to be broken down more quickly and for more of it to fit into a given area

Question 16

why does branching help glycogen to be broken down more quickly?

Answer 16

• the glycogen will be broken down using enzymes that will perform hydrolysis reactions to break the bonds
• if the molecule is branched, a lot more enzymes are able to act on the ends of chains at a given time, meaning that multiple hydrolysis

Question 17

starch - function

Answer 17

• energy storage molecule in plants
• made out of alpha glucose

Question 18

starch - composed of two subunits

Answer 18

1. amylose: long, unbranched chains (1,4) glycosidic bonds which are coiled (more compact)
2. amylopectin: branched chains (1,4) & (1,6) glycosidic bonds and can only be broken down more quickly by enzymes doing hydrolysis reactions

Question 19

cellulose - function

Answer 19

used to make a cell wall

Question 20

why is cellulose important to make a cell wall?

Answer 20

the cell wall is important for giving strength to the cell and stopping it from bursting or shrivelling

Question 21

cellulose - structure

Answer 21

• long chains of beta glucose
• these long chains are bunched together with cross-lines between them to make them extra long

Question 22

biochemical test for carbohydrates

Answer 22

benedicts test

Question 23

Benedicts test

Answer 23

• reducing sugars (monosaccharides)
• orange to brown = positive

Question 24

how to carry out the Benedicts test

Answer 24

• non-reducing sugars (sucrose)
• hydrochloric acid and sodium hydrogen carbonate solution
• then Benedict’s test
• needs to hydrolyse non-reducing sugar (acid) then neutralise pH

Question 25

test for starch

Answer 25

iodine test

Question 26

iodine test

Answer 26

• iodine solution
• blue/black = positive