Carbohydrates lab

Question 1

Starch is isolated from plant sources via ____ since starch is slightly soluble in H₂O

Answer 1

selective dissolution

Question 2

Starch is a good example of a ____.

homoglycan or heteroglycan

Answer 2

homoglycan

Question 3

What are the two polysaccharides that build up starch?

Answer 3

Amylose & Amylopectin

Question 4

Among the two polysaccharides that build up starch, which is linear (unbranched)?

Answer 4

Amylose

Question 5

The linear polysaccharide that builds up starch is connected by ____ glycosidic bonds

Answer 5

α-1,4-glycosidic bonds

Question 6

Among the two polysaccharides that build up starch, which is branched?

Answer 6

Amylopectin

Question 7

Amylopectin, similar to the linear polysaccharide that builds up starch via α-1,4-glycosidic bonds, the branching is linked via ____ glycosidic bonds

Answer 7

α-1,6-glycosidic bonds

Question 8

What saccharide will you isolate from liver?

Answer 8

glycogen

Question 9

what isolation principle ruptures the membranes of the liver so as to free glycogen?

Answer 9

homogenization

iirc, via boiling ito

Question 10

what reagent is used to remove the proteins of the liver via precipitation so as to free glycogen?

Answer 10

10% TCA

trichloroacetic acid

Question 11

what reagent is used to precipitate glycogen from the homogenized sample wherein it occurs via the losing of the H₂O shell surrounding the glycogen?

Answer 11

95%EtOH

ethanol

Question 12

what reagent is used to facilitate the precipitation of glycogen using the principles of salting-out?

Answer 12

NaCl

Question 13

the human liver composes how many percent of the body’s total mass?

Answer 13

10%

~10%

Question 14

what polysaccharide is the energy reserve of animals that provides sugar for 24-36 hours?

Answer 14

glycogen

Question 15

Identify the test based on principle

strong acid to dehydrate monosaccharide to produce furfural or hydroxymethylfurfural. Intermediate furfural derivatives will condense with α-naphthol

Answer 15

Molisch’s test

Question 16

Identify the test based on principle

formation of complex (complexation) with iodine

Answer 16

iodine test

Question 17

Identify the test based on principle

Cu²⁺ reduction; cupric oxide to cuprous oxide in a basic (sodium citrate) medium

CuO –> Cu₂O

Answer 17

benedict’s test

Question 18

Identify the test based on principle

Cu²⁺ reduction; cupric oxide to cuprous oxide in an acidic (acetic acid) medium

CuO –> Cu₂O

Answer 18

barfoed’s test

Question 19

Identify the test based on principle

Strong acid to dehydrate monosaccharide to produce furfural or hydroxymethylfurfural then condensation with resorcinol

Answer 19

seliwanoff’s test

Question 20

Identify the test based on principle

Strong acid to dehydrate monosaccharide to produce furfural or hydroxymethylfurfural then condensation with orcinol

Answer 20

bial’s orcinol test

Question 21

Identify the test based on principle

formyl functional group/prim alcohol oxidation to carboxylic acid by nitric acid

Answer 21

mucic acid test

Question 22

Identify the test based on principle

formyl group/2ndary alcohol oxidation to carboxylic acid/ketone, respectively, by phenylhydrazine

Answer 22

phenylhydrazine/osazone test

Question 23

positive result of molisch’s test

Answer 23

purple ring at interphase

Question 24

positive result of iodine test

Answer 24

• blue-black sol’n for starch
• red-pink sol’n for glycogen

Question 25

positive result of barfoed's test

Answer 25

brick-red ppt

Question 26

positive result of benedict's test

Answer 26

brick-red ppt

Question 27

positive result of seliwanoff's test

Answer 27

cherry-red solution

Question 28

positive result of bial's orcinol test

Answer 28

blue-green solution

Question 29

positive result of mucic acid test

Answer 29

broken glasslike/rhombic crystals | under a microscope

Question 30

positive result of phenylhydrazone/osazone test

Answer 30

yellow orange crystals

Question 31

# Identify the test based on reagents H2SO4, EtOH and α-naphthol

Answer 31

Molisch's test

Question 32

# Identify the test based on reagents Iodine solution

Answer 32

Iodine test | duh

Question 33

# Identify the test based on reagents CuSO₄, Na₂CO₃, Na₃C₆H₅O₇

Answer 33

Benedict's test

Question 34

# Identify the test based on reagents Cu(CH₃COO)₂, acetic acid

Answer 34

Barfoed's test

Question 35

# Identify the test based on reagents HCl, resorcinol

Answer 35

Seliwanoff's test

Question 36

# Identify the test based on reagents HCl, FeCl₃, and orcinol

Answer 36

Bial's orcinol test

Question 37

# Identify the test based on reagents concentrated HNO₃

Answer 37

mucic acid test

Question 38

# Identify the test based on reagents phenylhydrazine

Answer 38

phenylhydrazone/osazone test

Question 39

# Identify the qualitative tests based on what they're testing for reducing sugars

Answer 39

- Barfoed's test - Benedict's test

Question 40

# Identify the qualitative tests based on what they're testing for polysaccharide presence

Answer 40

- Molisch's test - Iodine test

Question 41

# Identify the qualitative tests based on what they're testing for ketohexoses | or ketoses

Answer 41

Seliwanoff's test

Question 42

# Identify the qualitative tests based on what they're testing for pentoses

Answer 42

Bial's orcinol test

Question 43

# Identify the qualitative tests based on what they're testing for galactose and lactose

Answer 43

mucic acid test

Question 44

# Identify the qualitative tests based on what they're testing for saccharides with free carbonyl group at C1 or C2

Answer 44

Phenylhydrazone/Osazone test

Question 45

What is the solvent system used in tlc of carbs?

Answer 45

Acetonitrile:Water (85:15)

Question 46

What is the visualizing agent used to view spots in the chromatoplate?

Answer 46

p-anisaldehyde

Question 47

the more -OH grps there are, the ____ polar the sugar is; therefore, it will be more adsorbed by the silica gel.

Answer 47

more polar

Question 48

In quantitative analysis, the amount of carbohydrates present in a given sample can be measured by ____

Answer 48

Nelson's method

Question 49

What method in quantitative analysis of carbs is based on the capacity of the free reducing groups of sugars in a carbohydrate sample to reduce Cu²⁺ in an alkaline solution?

Answer 49

Nelson's method

Question 50

The Colorimetry of Absorbance is based on the intensity of the product of arsenomolybdate and the copper oxide solution and is measured at ____nm.

Answer 50

480

Question 51

sodium potassium tartrate is also known as?

Answer 51

rochelle salt

Question 52

In Nelson's method, what reagent serves as the oxidation agent?

Answer 52

CuSO₄

Question 53

What reagent prevents the precipitation of Cu(OH)₂?

Answer 53

Sodium Potassium Tartrate | Rochelle salt

Question 54

In Nelson's method, what reagent is added to dissolve Cu₂O and is converted to molybdenum blue?

Answer 54

Arsenomolybdate reagent

Question 55

The more intense the blue coloration is (molybdenum blue), the greater the amt of Cu²⁺, and the ____ the amt of sugar there is. | greater or lesser

Answer 55

greater

Question 56

Acid hydrolysis is a complete hydrolysis, therefore it yields what products?

Answer 56

monosaccharides | glu fru galac etc

Question 57

Enzymatic hydrolysis is what type of hydrolysis? | complete or incomplete?

Answer 57

incomplete | coz it breaks specific bonds onli ## Footnote yields a mixture of glu, mal, & other hydrolysates (amylase is an example)

Question 58

# nice to remember: why is basic hydrolysis not used in the exp?

Answer 58

bcoz aldo & keto grps are sensitive to strong base attacks, leading to its epimerization (aldose-ketose interconvertion) ## Footnote syempre magfafalse ibang tests like say for example fructose won't be a ketose na or smth