Ch. 4 Carbohydrates (Exam 1)

Question 1

What is the empirical formula for a carbohydrate?

Answer 1

C(n)H(2n)O(n)

Question 2

What functional groups do carbs consist of?

Answer 2

Hydroxyls and carbonyls

Question 3

Are carbs water soluble?

Answer 3

Yes

Question 4

What are carbs a good source of?

Answer 4

Rapid energy

Question 5

What is the range of carbons in a monosaccharide?

Answer 5

3-8

Question 6

Which sugars have aldehyde groups?

Answer 6

Aldoses

Question 7

Which sugars have ketone groups?

Answer 7

Ketoses

Question 8

How many carbonyls are in a monosaccharide?

Answer 8

1

Question 9

What suffix denotes sugar?

Answer 9

-ose

Question 10

How are monosaccharides named?

Answer 10

Based on number of carbons

Question 11

What method is used to draw a monosaccharide?

Answer 11

Fischer projection

Question 12

Which way does the OH group on the penultimate (next to last) carbon face for D stereochemistry?

Answer 12

Right

Question 13

Which way does the OH group on the penultimate (next to last) carbon face for L stereochemistry?

Answer 13

Left

Question 14

How do you decide the stereochemistry of a monosaccharide?

Answer 14

The penultimate (next to last) carbon with the OH group determines where stereochemistry will be L or D

Question 15

Which carbon is the most oxidized?

Answer 15

C1 - the carbonyl/carbon at top of Fischer projection

Question 16

Do most organisms metabolize L or D sugars?

Answer 16

D sugars

Question 17

What are epimers?

Answer 17

Epimers are sugars differing at different carbon atoms other than the D or L carbon

Question 18

What are 5 common types of monosaccharides discussed in the lecture?

Answer 18

1) Erythose
2) Ribose
3) Glucose
4) Galactose
5) Fructose

Question 19

How many carbons are needed to form a sugar ring?

Answer 19

5 or more

Question 20

What reactants are needed to form a hemiacetal/hemiketal (HINT: 2 key function groups)?

Answer 20

Carbonyl and hydroxyl (OH)

Question 21

What is an anomeric carbon, and what does it determine about a cyclic molecule?

Answer 21

The carbon that was the carbonyl in acyclic form and decides whether the sugar is in alpha or beta conformation in cyclic form

Question 22

How can you determine whether an anomeric carbon is in alpha or beta conformation?

Answer 22

• Alpha: anomeric carbon faces up on same side of ring w/ 6th carbon
• Beta: anomeric carbon faces down on opposite side of ring w/ 6th carbon

Question 23

What is the key difference between reducing and non-reducing sugars (HINT: something about the anomeric carbon)?

Answer 23

Reducing sugar: free anomeric sugar

Non-reducing sugar: no free anomeric sugar

Question 24

What are 2 examples of reducing sugars?

Answer 24

1) Maltose

2) Lactose

Question 25

What are 2 examples of non-reducing sugars?

Answer 25

1) Sucrose

2) Trehalose

Question 26

How do amylose molecules bond together?

Answer 26

Alpha 1,4 glycosidic bonds