carbohydrate structure and function

Question 1

Hemiacetals are formed by combining an acetal group with what other functional group?

Answer 1

Alcohol

Question 2

Characteristic of Pyranose

Answer 2

very stable and common in nature

Question 3

What is a pyranose

Answer 3

Six-carbon, cyclic sugar.

Question 4

Which conformation has the lowest energy

Answer 4

Chair conformation, so they prefer to be in this position.

Question 5

which group of sugars don’t form chair conformation

Answer 5

Furanose

Question 6

Im six carbons long BUT, form a 5 carbon ring. What I’m I?

Answer 6

A furanose

Question 7

Comparing between Furanose and Pyranose, which is more stable in nature.

Answer 7

Pyranose because of its chair conformation which takes on a lower energy and stable position.

Question 8

what allows Anomerization possible

Answer 8

Aldehyde is a planar function group; Hydroxide from carbon 6 or 5 can attach either side resulting in either Alpha or Beta ring

Question 9

An anomer is a special type of which isomer?

Answer 9

Epimer

Question 10

What is Mutarotation

Answer 10

Tendency of a cyclic glucose that was an alpha anomer to be hydrolyzed into a strain chain that will either become Beta anomer or back to its alpha conformation.

Question 11

Define Lactone

Answer 11

Any six membered cyclic esters

Question 12

Define Tautomerization

Answer 12

A ketose, a non reducing sugar, is converted to an enol then to an aldose, which is a reducing sugar.

Question 13

True or False:

A Ketose is a reducing sugar

Answer 13

False

Question 14

Hydroxyl groups commonly play which role in esterification reactions?

Answer 14

Nucleophile

Question 15

what is a glycoside

Answer 15

A molecules that contains a bond between a functional group and one of the carbons of the sugar.

That bond is Called the glycosidic linkage.

The same kind of linkage also found between di- and polysaccharides.

Question 16

What type of bond joins phosphate and glucose in β-D-glucose-6-phosphate?

Answer 16

Glycosidic

Question 17

Phosphofructokinase-1 (PFK-1) catalyzes the transformation of fructose-6-phosphate to fructose-1,6- bisphosphate. What is the role of the 1- hydroxyl in the reaction?

Answer 17

Nucleophile

Question 18

One Example of a nucleophilic attack

Answer 18

Phosphorylation

Question 19

True or False: Cellulose and amylose are polysaccharide chains of glucose that only differ in the orientation of their glycosidic linkages.

Answer 19

True

Question 20

Many adults are unable to digest lactose; a disaccharide of galactose and glucose. What characteristic of lactose must be the underlying cause?

Answer 20

beta (1-4) linkage

Question 21

Amylose is a linear chain of which glycosidic bond

Answer 21

Alpha 1-4

Question 22

Cellulose is a structural polysaccharide for plant cell wall

which type glycosidic bond does it contain.

Answer 22

Beta 1-4

Question 23

Even though amylopectin and glycogen are both polysaccharides with branch points. what distinctifies them

Answer 23

Amylopectin branch points are far in between (every ~25 carbs)
Glycogen branch points are closer at (every ~10 carbs)

Question 24

Aldonic acids are compounds that

Answer 24

Have been oxidized, and have acted as reducing agents.

Question 25

Define Mutarotation

Answer 25

Interconversion between anomers of a compound

Question 26

Tautomerization

Answer 26

The interconversion of bonds, to undergo keto-enol shift.

ex: A ketone converted to an aldose.

Question 27

What is amylose used for

Answer 27

storage of glucose in plants.

Question 28

beta- amylase

Answer 28

Cleaves amylose at the non-reducing end of the polymer to yield maltose exclusively.

Question 29

Alpha-amylase

Answer 29

Cleaves amylose anywhere yielding short polysaccharides, maltose and glucose.

Question 30

These molecules are cyclic forms of Ketose and aldoses respectively

Answer 30

Hemiketal and Hemiacetal