Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
25 Cards in this Set
- Front
- Back
|
What is an oligosaccharide?
Name the two types: |
A short, non-repetitive complex carbohydrates.
1. Glycoproteins 2. Glycolipids |
|
|
What is a polysaccharide?
Name the two types |
Long, repetitive complex carbohydrates.
1. Glycogen 2. Glycosaminoglycans |
|
|
In order for monosaccharides to attach to a protein or lipid what needs to happen first?
|
They need to be nucleotide activated.
Usually by UDP. Exceptions: *GDP-mannose *GDP-L-fucose *CMP-acetylneuraminic (sialic) acid |
|
|
Where are monosaccharides added?
Any exceptions? |
To the reducing end- i.e. the hydroxyl group of the 1st carbon.
Exceptions: *Amide group-Asparagine *Carboxyl group-Bilirubin |
|
|
What are some functions of glycosylation?
|
*Glycosylation increases solubilty.
* Distributes/maintains proteins in the aqueous environment of the human body *Clears out foreign substances (toxins/drugs) *removes degradation products (steroids/heme) *Contributes to cell recognition in glycoproteins and glycolipids. * Contributes to the mechanical function of glycosaminoglycans in the extracellular matrix |
|
|
How is UDP-glucuronate formed?
What catalyzes this reaction? |
By oxidation of UDP glucose.
UDP-glucose+ NADH--> UDP-glucuronate Catalyzed by UDP dehydrogenase |
|
|
What is the function of UDP-glucuronate?
|
Forms glucuronides which are resposible for removal of: bilirubin, steroid hormone, drugs, and toxins from the human body.
|
|
|
What catalyzes the following reaction:
UDP-glucuronate + ROH-> Glucuronide-> bile or urine |
UDP-glucuronate transferase
|
|
|
What causes jaundice (yellow skin and sclera) in new borns?
|
Low bilirubin glucuronyltransferase levels.
The inability to conjucate and excrete bilirubin. Note: bilirubin is excreted into the bile. |
|
|
What is biliruben and where is it secreted to?
|
Bilirubin is a degradation product of the heme group of hemoglobin.
It is secreted into the liver. |
|
|
What are the components of glycosaminoglycans?
|
*acidic sugar
*N-acetylated amino sugar NOTE: Keratan sulfate has galactose instead of an acidic sugar. |
|
|
Name the classes of glycosaminoglycans:
|
1. Hyaluronic Acid
2. Chondriotin sulfate 3. Dermatan Sulfate 4. Keratan sulfate 5. Heparan sulfate 6. Heparin |
|
|
Where are glycosaminoglycans synthesized?
|
In the golgi EXCEPT hyaluronic acid which is synthesized in the plasma membrane.
|
|
|
What are the main properties of glycosaminoglycans?
|
1. They are negatively charged which attracts a lot of water and makes them behave like sponges.
2. They are synthesized on a protein core (except hyaluronic acid) 3. They are sulfated (except hyaluronic acid) 4. They contain a B-glycosidic bond (except heparin and heparan sulfate). 5. They are part of extracellular matrix molecles or cell membrane molecules |
|
|
Where is hyaluronic acid found?
|
1. Cartilage
2. Connective tissue (loose) 3. Synovial fluid 4. Vitreous humor of the eye |
|
|
What is hyaluronic acid important for?
|
1. Morphogenesis
2. Embryogenesis 3. Wound healing 4. Used in eye surgery (healon) 5. Used to treat osteoarthritic pain NOTE: without hyaluronic acid there is no vertebrate life! |
|
|
Where is chondroitin sulfate found?
|
Mostly in Cartilage
NOTE: it is the most abundant glycosaminoglycan in the human body! |
|
|
Where can dermatan sulfate be found?
|
1. Skin
2. Blood vessels 3. Heart valves NOTE: accumulation of dermatan sulfate in the mitral valves leads to mitral valve prolapse (thickening and abnormal placement of the valve into the left atrium) |
|
|
Deficiency of _______ results in insufficient sulfation of keratan sulfate in the cornea causing macular corneal dystrophy (cloudy corneas and visual impairment)
|
Carbohydrate sulfotransferase 6 (CHST 6).
|
|
|
Where is Keratan sufate (type 1 and 2) found?
|
KS1- found in the cornea of the eye (linked to the amide of ASN)
KS2- found in the cartilage (linked to the hydroxyl of serine) |
|
|
Where is Heparin found and what is it's function?
|
Heparin is stored and released by Mast Cells.
It is used as an anticoagulant in medicine. |
|
|
Where is Heparan Sulfate found and how does it differ from Heparin?
|
Heparan Sulfated is less sulfated than Heparin.
1. It is part of a major proteoglycan (perlecan) in basement membranes. 2. Compenent of cell surface molecules and receptors |
|
|
What is a proteoglycan?
|
A protein with at least one glycosaminoglycan chain attached
|
|
|
How are proteins linked to glycosaminoglycans?
|
Proteins are linked to a glycosaminoglycan through a linker region. The linker region is attached to either:
1. The amide group of asparagine OR 2. The hydroxyl group of serine |
|
|
What is aggrecan (cartilage proteoglycan) comprised of?
|
1. Chondroitin sulfate
2. Keratin Sulfate II |
