Carbohydrates 5

Question 1

Proteoglycans vs. Glycoproteins

Answer 1

Proteoglycans: chain of sugars in EC matrix
Glycoproteins: short branches of sugars covalently bound to membrane proteins hanging out into EC matrix
They help mediate cell-cell communication and structure of cells around each other

Question 2

Sugars are attached where?

Answer 2

In the golgi

Question 3

Carbohydrates facilitate what?

Answer 3

excretion of poorly water soluble metabolites

Question 4

Functions of Extra cellular matrix

Answer 4

elasticity to cartilage, tensile strength to tendons, cohesion to connective tissue, viscosity to ocular fluids

Question 5

Components of a proteoglycan

Answer 5

1. Hyaluronic Acid
2. linker protein
3. Glycosaminoglycans (GAGs) –have a negative charge so positive ions are attacted to them and trapped within the ECM
4. Core Protein

Question 6

Trapping of H2O in ECM

Answer 6

GAGs are negatively charged so they attract positive ions which leads to entrapment of water in the ECM and gives it its elastic properties

Question 7

Chondroitin Sulfate

Answer 7

sulfation on N-acetyl-galactosamine

found in cartilage, tendons and bone

Question 8

Dermatan Sulfate

Answer 8

Sulfation on both sugars

found in skin, blood vessels and valves

Question 9

Heparin

Answer 9

Sulfation on both sugars

found in liver

Question 10

Heparan Sulfate

Answer 10

sulfation on N-acetyl-glucosamine

found in cell surface

Question 11

Hyaluronic Acid

Answer 11

No sulfation

found in joints and ocular fluid

Question 12

Keratan Sulfate

Answer 12

sulfation on N-acetyl-glucosamine

found in cartilage, cornea

Question 13

Degradation of proteoglycans

Answer 13

each one requires its own set of different enzymes depending upon the bonds it has (specific acid hydrolases), each require specialized vacuolar enzymes

Question 14

Mucopolysaccharidosis

Answer 14

defect of one of the many proteoglycan-degrading hydrolases; usually exhibit skeletal deformation

Question 15

Hunter Disease

Answer 15

Dermatan sulfate and heparan sulfate accumulate; iduronate sulfatase defective; intellectual disability and skeletal abnormalities

Question 16

Hurler-Scheie Disease

Answer 16

Dermatan sulfate and heparan sulfate accumulate; alpha-iduronse defective; intellectual disability and skeletal abnormalities

Question 17

Sanfilippo’s (A, B, C, D) Disease

Answer 17

Heparan Sulfate; A/B/C/D root in different defects of heparan sulfate degradation; intellectual disability and skeletal abnormalities

Question 18

For Glycosylation of proteins, the cell needs to synthesize mainly…

Answer 18

Mannose, Galactose, Fucose–all synthesized from Glucose; interconversion of sugars

Question 19

Glycosylation of Metabolites and Xenobiotics–acetaminophen ex.

Answer 19

excretion of poorly water soluble molecules; occurs in liver and requires production of UDP-glucuronic acid to serve as substrate; ex. UDP-glucuronic acid transfer glucuronic acid to acetaminophen and it can be excreted

Question 20

Bilirubin

Answer 20

breakdown product of heme and water insoluble; needs to be conjugated to glucuronic acid in liver to be excreted; defect in hepatic glucuronosyltransferase UGT leads to accumulate of unconjugated bilirubin; jaundice

Question 21

5 Mechanisms Used to Regulate Carb Metabolism

Answer 21

Substrate availability, allosteric regulation, covalent modification (phosphorylation), Translocation of GLUT4 transporter, rate of protein synthesis