lecture 3-di/oligosacchrides

Question 1

Define monomer

Answer 1

a molecule that can bond with another forming a polymer or oligimer

Question 2

define dimer

Answer 2

a molecule made of 2 monomers

Question 3

define oligomer

Answer 3

a polymer with a few monomeric units

Question 4

define disacchride

Answer 4

is a molecule made of 2 monomeric units that are joined together by a glycosidic bond connecting a non-reducing end and a reducing end

The OH group can react at 1,2,3, or 6

Question 5

are all dissachrides reducing?

Answer 5

no sucrose is the exception

Question 6

what are the three dissachrides

Answer 6

1. sucrose
2. mannose
3. lactose

Question 7

define reducing end

Answer 7

the free end that is able to particiapte in a redox rxn (single)

Question 8

define non-reducing end

Answer 8

that part that is involved in the glycosidic bond and is not free to be involved in a rxn (taken)

Question 9

define invert sugar

Answer 9

is a flavoring agent that is created by the hydrolysis of sucrose under acidic conditions into glucpse and furctose making it sweetner

Question 10

define oligiosacchride

Answer 10

is a chain of 3-20 monosachride units connected by glycosidic bonds which are typically not found in large amounts in food like dextrin

Question 11

Describe the action and products of the enzymes: maltase,

Answer 11

1. Maltase
   
   1. action: hydrolyzes glycosidic bond in maltose into two D-glucose units
   2. products: 2 D-glucose units
   3. nutrition role: allows body to digest maltose which is found in foods like grains, and malted foods

Question 12

Describe the action and products of the enzymes:Maltaseglucoamylase

Answer 12

2. Maltaseglucoamylase
   
   1. at the non-reducing ends of starch and dextrins will hydrolyze the alpha 1,4 bond betwen molecules
   2. glucose units
   3. helps with digestion and absorbtion of complex carbs specifically starch

Question 13

Describe the action and products of the enzymes: lactase

Answer 13

1. hydrolysizes lactose into its monosachride units
2. glucose and galactose
3. enables the digestion of lactose which may not continue into adult hood many stop producing this enzyme

Question 14

describe the action and products of the enzyme:Sucrase-isomaltase

Answer 14

4. Sucrase-isomaltase
   
   1. complex enzyme working with two different parts; sucrose and and isomaltose which is a a molecule of 2 glucose units that has a different linkage than that of maltose. It has 1-6 instead of 1-4. So basically these break down the two molecules into their monomers
   2. glucose, fructose and smaller polysacchrides
   3. helps digest complex carbohydrates into absroable forms

Question 15

describe the action and prodcucts of the enzyme:invertaste

Answer 15

5. Invertaste
   
   1. hydrolyzes the beta-fructofuranosidic bond in sucrose
   2. glucose and fructose

Question 16

• Describe the galacto- oligosaccharides

Answer 16

1. galacto-oligosacchrides:
   
   • are oligosacchrides that have one to three galactose monomer linked to a sucros moleculr
     
     • raffinose
     • satchyose
     • verbascose
   • found in high amounts in legumes
   • they pass into the colon undigested for the gut microbiata to decide their fate as there is no enzyme for them

Question 17

describe fructo-oligosaccharides

Answer 17

• they follow the basic structure of oligomers of beta-D-fructofuranosyl linked in 2,1 and are biosyntheizes from succrose
• they have some prebiotic properties as they are not digested in the upper intestine and will encourage the growth of gut baceria producing short chain fatty acids

Question 18

• why add calcium hydroxide during the production of sugar cane?

Answer 18

because it avoids hydrolysis of sugar into its monomers

Question 19

• why add sulphur dioxide during sugar beat extraction>

Answer 19

Overall, the addition of sulfur dioxide during sugar beet extraction helps improve the quality, appearance, and shelf life of the extracted sugar product

Question 20

• what are important notes regarding the nomenclature of oligosacchrides
  -

Answer 20

anomeric conformation is either alpha or beta
- stereochemistry is only mentioned if it is L
- the first 3 letters of the monosacchride are used in the name the exception being glucose (glc)
- the type of cyclic form is depectied as p for pyranosyl or f for furanosyl
- if there is a uronic acid then an A is added
- the bond position is depectced as an arow or comma

Example: matlose= **αGlcp(1→4)-Glc  or αGlc-1,4Glc**

Question 21

• what is a reducing sugar

Answer 21

carbs that have a free aldehyde group or can form one through isomerisation. That free aldehyde group allows them to be a reducing agent since they can donate electrons to other molecules

Question 22

• describe benedicts test

Answer 22

is a test to see if there are reducing sugars by using benedicts reagent which has copper sulfate in it. When a reducing sugar is heated in alkaline solution as the one presented the copper ions are reduced forming a red brown perciptate. So if there is a red brown perciptate it means there are reducing sugars that have donated electrons to reduce copper

Question 23

• explain glucose oxidation which is an example of a reducing sugar

Answer 23

glucose can open its ring structure to form an aldehyde group acting like a reducing sugar. When glucose is oxidized it truns into gluconic acid and reduces copper into coper I oxide

Question 24

• explain the oxidation of fructose

Answer 24

since fructose is a ketose sugar it does not have an aldehyde group that can be oxidized directyl and therefore must undergo isomerization to glucose or mannose to be oxidized. The steps go as follows fructose forms a enediol intermediate which then can isomerize into glucose or mannose and then oxidation can occur.