exp 5: qualitative analysis of carbohydrates

Question 1

most abundant biomolecule in nature

Answer 1

carbohydrates

Question 2

2 purpose in plants

Answer 2

cellulose:
provide structure integrity in roots and stem

starch:
storage of glucose for the production of biochemical energy

Question 3

functions in humans

Answer 3

provide energy for the cell through oxidation of monosaccharides

being part of the structural framework of nucleotide
acting as a messenger in cell communication and cell recognition

Question 4

carbs are molecules made up of what type of functional groups

Answer 4

hydroxyl groups
- allow carbs to observe intermolecular H bonding
= high bp and mp
= soluble in polar solvents like water

either an aldehyde grp -CHO or ketone grp C=O

[both functional groups are polar]

Question 5

upon hydrolysis of carbs what does it yield

Answer 5

simpler molecules that also contain these aldehyde or ketone groups

Question 6

simplest carbohydrates

Answer 6

monosaccharides

Question 7

how can monosaccharides be classified

Answer 7

based on
- type of carbonyl grp (aldose/ ketone)
- no. of C present in an open chain
(3C-triose, 4C-tetraose, 5C-pentose, 6C-hexose)

Question 8

monosaccharides can form glycosidic linkages w one another to form

Answer 8

glycosidic linkages with one another to form more structurally and biochemically complex carbohydrates (monosaccharides, oligosaccharides, and polysaccharides)

Question 9

reagents

Answer 9

glucose
amylose
maltose
xylose
fructose
galactose
lactose
sucrose

Molisch Reagent
conc. H2SO4
iodine soln.
Benedict’s Reagent
Barefoed’s Reagent
Seliwanoff’s Reagent
Bial’s Orcinol Reagents

Question 10

how many drops of each sugar sample

Answer 10

15 drops

Question 11

which reagent puts 5 drops of reagent and 25 drops of reagent

Answer 11

5 drops:
Molisch Reagent (carbs)
Iodine soln (starch, amylase)

25 drops:
Benedict’s Reagent (reducing sugar, fructose and glucose)
Barfoed’s Reagent (recucing monosa and reducing disa)
Seliwanoff’s Reagent (ketones, friuctose and aldose)
Bial’s Orcinol Reagent (pentose)

Question 12

instrument used

Answer 12

water bath

Question 13

which test needs to heat and for how long

Answer 13

Benedict - 2min
Barfoed- 5min
Seliwanoff - until observable changes
Bial

Question 14

how long will reducing mono and di will take to form

Answer 14

reducing mono - less than 2 to 3 min (orange or red ppt)

reducing di - take up to 10min

Question 15

waste disposal

Answer 15

excess sugar - sink
moli and seli - non halo
iodine - halo
3 B’s - metal containing waste

Question 16

this help dehydrate carbs

Answer 16

conc. sulfuric acid

Question 17

+ve result of Molisch Test

Answer 17

purple/ violet ring

Question 18

+ve result of iodine

Answer 18

blue black color

Question 19

+ve result of Bendeict’s

Answer 19

red, yellow, green

Question 20

+ve result of Seliwaoff’s

Answer 20

ketose -red color, fast
aldose - faint pink, slow

Question 21

+ve result of bial’s Orcinol

Answer 21

blue-green color