Monosaccharides

Question 1

What is the empirical formula for carbohydrates?

Answer 1

C(H₂O)_n

Question 2

A monosaccharide is a linear chain with ___ or more carbons

Answer 2

3

Question 3

Distinguish between an aldose and a ketose

Answer 3

an aldose is a carbohydrate that has an aldehyde (at C1), whereas a ketose is a carbohydrate that has a ketone (at C2)

Question 4

What are glycans?

Answer 4

glucose polysaccharides

Question 5

Glycolysis is a ___-enzyme pathway used by all living cells

Answer 5

10

Question 6

Glycolysis converts ____ into _____

Answer 6

glucose (6C) into 2 pyruvate (3C)

Question 7

Glycolysis produces a net synthesis of ___ ATP and ___ NADH

Answer 7

2 ATP and 4 NADH

Question 8

Distinguish between D and L configuration

Answer 8

For monosaccharides, the D/L configuration only considers the chiral center farthest away from the carbonyl:

If OH group Fischer projection is pointed to the R, the molecule is labeled as D

If the OH group Fischer projection is pointed to the L, the molecule is labeled as L

Question 9

galactose is the ____ epimer of glucose

Answer 9

C4

Question 10

Mannose is the ____ epimer of glucose

Answer 10

C2

Question 11

Distinguish how the OH and carbonyl arrangements differ between glucose in fructose in terms

Answer 11

glucose is an aldose whereas fructose is a ketose

C2 for glucose is a chiral center(and OH points to the R in the Fischer projection)

C2 for fructose is the ketone (C1 is a CH2OH and therefore not a chiral center)

C3, C4, and C5 have the same OH arrangement

Glucose and Fructose are constitutional isomers

Question 12

How many carbons does glyceraldehyde have? How many chiral centers? Aldose or ketose?

Answer 12

glyceraldehyde has 3 C, 1 chiral center, and is an aldose

Question 13

How many C does dihydroxyacetone have? How many chiral centers? Aldose or ketose?

Answer 13

dihydroxyacetone has 3C, no chiral centers, and is a ketose (flanked by CH2OH on each side)

Question 14

Name how many carbons and chiral centers each of the following have along with whether it is an aldose or ketose:

1) D-Ribose
2) D-Arabinose
3) D-Xylose
4) D-Ribulose
5) D-Xylulose

Answer 14

All are 5C monosaccharides

1) D-Ribose: 3 chiral centers, aldose
2) D-Arabinose: 3 chiral centers, aldose
3) D-Xylose: 3 chiral centers, aldose
4) D-Ribulose: 2 chiral centers, ketose
5) D-Xylulose: 2 chiral centers, ketose

Question 15

Name whether the following are aldoses or ketoses and how many chiral centers are in each:

1) glucose
2) galactose
3) mannose
4) fructose

Answer 15

*Note all are 6 C sugars

1) glucose: aldose, 4 chiral centers
2) galactose: aldose, 4 chiral centers
3) mannose: aldose, 4 chiral centers
4) fructose: ketose, 3 chiral centers

Question 16

What is the formula for finding # stereoisomers in a compound?

Answer 16

2ⁿ

n = number of chiral centers the molecule has

Question 17

What is an epimer?

Answer 17

Epimers are 2 molecules in which only differ in one chiral center

Question 18

D-arabinose and L-arabinose are _______ (what type of isomer?)

Answer 18

enantiomers (all chiral centers are flipped)