14- Intro to Carbohydrates

Question 0

What is the most important monosaccharide, and what polysaccharides are made up of this saccharide?

Answer 0

Glucose is the most important monosaccharide.

Other saccharides made up of glucose are starch, cellulose, and glycogen.

Question 1

What are carbohydrates? Aldoses? Ketoses?

Answer 1

Carbohydrates are polyhydroxy aldehydes, polyhydroxy ketones, or compounds that can be hydrolyzed to give these as a product.

A monosaccharide having an aldehyde is an aldose.

Ketoses are a monosaccharide with a ketone group.

Question 2

Pyan and furan are organic compounds for which sugar structures? How many atoms are per ring?

Answer 2

Pyran is a cyclized six carbon sugar. Made from glucose, they form pyranoses.

Furan is a cyclized five carbon sugar. Made from fructose, they form furanoses.

Question 3

What is a mutarotation, and where does it take place?

Answer 3

Mutarotation are changes in configuration at the anomeric carbon by ring opening and closing.

Question 4

What are two conformations of 6 membered rings?

Answer 4

Boat and Chair

Question 5

How are sugars named?

Answer 5

Sugar acids are named by their terminal group.

If you have a terminal aldehyde ==> -aldonic acid
If you have a terminal hydroxyl group ==> -uronic acid

Question 6

Name and describe two commonly found modifications of sugars.

Answer 6

1) Deoxy sugars : replace a hydroxyl group with a hydrogen (e.g. 2-deoxyribose)
2) Amino Sugars: replace a hydroxyl group with an amine group (e.g. glucosamine or galactosamine)

Question 7

What is a glycoside and an aglycone?

Answer 7

Glycoside are when the anomeric hydroxyl group of a sugar reacts with another hydroxy compound

Aglycone is the sugar not providing the anomeric carbon.

Question 8

Which of the three most important polysaccharides have alpha linked sugars? Beta linked sugars? What is the importance of this?

Answer 8

Alpha linked - sucrose (glucose-fructose link), amylose (glycoside-amyloopectin)
Beta linked - lactose (galactose-glucose link), cellulose

…Whys is it important?

Question 9

Name three important disaccharides and tell which have alpha or beta linked sugars

Answer 9

sucrose (alpha glucose-fructose link)
amylose (alpha glycoside-amylopectin)
lactose (beta galactose-glucose link)

Question 10

Tell what glycoaminoglycans are, and name two important ones

Answer 10

Glycoaminoglycans (GAGS) are unbranched polysacchairdes made up of repeating disaccharides where one is an amino sugar and the other is a uronic acid.

Two important ones:

1) Hyaluronic acid: the only GAG not a sulfate or attached to a protein.
2) Heparin : inhibitor of blood clotting (glucosamine and iduronic acid)

Question 11

In the A, B, O blood group substances, where is the difference in the structures of the olgosaccharides located? How many sugars are different?

Answer 11

Differences are due to the presence or absence of N-acetyl-galactosamine or galactose linked to the penultimate galactose by a C1 or C3 linkage.

5 to 6 sugars are different.