Carbohydrates

Question 1

Describe the cause/effect of Hurler’s syndrome (iduronidase deficiency) and Hunter’s syndrome (X linked iduronidase suphatase deficiency)

Answer 1

GAGs are normally degraded by lysosomal hydrolases - these dereditary diseases lead to enzyme deficiencies. These complex carbohydrates, therefore, accumulate within the lysozome of the cell and the cell begins to bulge which leads to deformity and mental retardation.

Question 2

Describe Glycoprotein storage disease - how do we test for it?

Answer 2

It is a clinically progressive hereditary disorder that causes a deficiency in lysosomal hydrolases - which cause accumulation of partially degraded structures in the lysosome

We test for oligosaccharides in the urine to diagnose this disease

Question 3

What do you call a one, two, three

five, six or seven carbon carbohydrate?

Answer 3

1= monosaccharide

2= disaccharide

3= triose

5= pentose

6= hexose

7= heptose

Question 4

What is the difference between an aldose/ketose carbohydrate?

Answer 4

aldose = aldehyde group

ketose = ketone group

Question 5

Name a few common 6 carbon carbohydrates

Answer 5

Glucose

Fructose

Galactose

Mannose

Question 6

Are the vast majority of sugars L or D sugars?

Answer 6

D sugars

Question 7

What is an isomer?

Answer 7

same chemical formula but different structures

i.e) glucose and fructose have the same chemical formula, but they have different structures

Question 8

What is an enantiomer?

Answer 8

Structures that are mirror images of eachother

D and L sugars

Question 9

What is the difference between a D sugar and an L sugar?

Answer 9

D sugar= OH group on the asymmetric carbon farthest from carbonyl carbon on right

L sugar= OH group on the asymmetric carbon farthest from carbonyl carbon on left side

Question 10

What do we call a 6 member ring that is a product of cyclisation?

Answer 10

a Pyranose

Question 11

What is the difference structurally between an alpha conformation of an anomer and a beta conformation of an anomer?

Answer 11

alpha conformation has the hydrogen facing up and the beta conformation has the hydrogen facing down

Question 12

Which carbon in a ring is the anomeric carbon?

Answer 12

the anomeric carbon is at C1 of an Aldose or C2 of a ketose - it is traditionally the carbon that has a carboxyl group attached to it

Question 13

How does an anomer of a saccharide differ in structure?

Answer 13

It only differs in structure at the anomeric carbon

Question 14

Sugar can act as what sort of agent?

Answer 14

it can act as a reducing agent - due to the OH group

Question 15

Describe a glycosidic bond

Answer 15

It is a bond between two carbohydrates at the 1 and 4 carbons (usually)-

the name of the bond depends on the numbers of carbons, the position of the anomeric hydroxyl group (alpha or beta)

Question 16

What is the general structure of GAGs?

Answer 16

they are a repeating disaccharide unit

with an acidic sugar and an amino sugar repeat units

Question 17

What are the functions of proteoglycans?

Answer 17

They are found in connective tissue and cartilage (they contain the hyluronic acid GAG that makes up the extracellular structure in cartilage and connective tissue) They act as molecular sieves.

Question 18

What are GAGs?

Answer 18

Glycosaminoglycans = large complexes of negatively charged unbranched heteropolysaccharide chaines - they bind large amounts of water and make up the extracellular matrix

Question 19

What are glycoproteins used for? What are they?

Answer 19

Glycoproteins are proteins with attached oligosaccharides - they contain no glucose.

They serve to sort proteins into various compartments, acting as enzymes, hormones, antibodies and structural proteins.

Question 20

What type GAGs are present in synovial fluid of joints, humor of eye, loose connective tissue and cartilage?

Answer 20

Hyaluronic acid which is a lubricant and shock absorber GAG found in all of these areas

Question 21

Which type of GAG is found in the mast cells that line arteries in liver, lungs and skin?

Answer 21

Heparin = which acts as an intracellular anticoagulant GAG all of these places

Question 22

What are the proteoglycans (PG) ?

Answer 22

They are glycosaminoglycan chains with protein cores and protein links attached to the hyaluronic acid backbone

Question 23

What is a common example of glycoproteins in the body?

Answer 23

Mucins (80% carbohydrate) act as protective lubricants in the GI and GU tract