Module 5 Flashcards
carbohydrates
What are the use of carbohydrates?
Source of energy/stored fuels (glycogen granules)
Provide structure to cells and organisms (cellulose in plants, chitin in arthropods)
Cell biology
-major component cell surface
Influence the function of proteins
recognition interaction
Information molecules
Why are cell surface sugar important
Cell-cell adhesion
Bacteria adhesion
Virus attachment to host cell
Binding of toxin to cell surface
What does gene encodes
Protein, no surgars
What defines monosaccharide
The simplest form of sugar (basic unit of carbohydrates)
Aldehyde or ketones that ahve 2 or more hydroxyl groups
[C-H2O]n (carbon hydrate)
What are aldose
aldehyde group
What are ketose
ketone
How to define glyceraldehyde
Has a single asymmetric (chiral) carbon atom
D- and L- are enantiomers or mirror images
What are the number of carbon atoms monosaccharides can have
More or equal to 3 carbon
What are 3 carbon sugars called
triose
What are 4 carbon sugars called
tetrose
What are 5 carbon sugars called
pentose
What are 6 carbon sugars called
hexose
What are 7 carbon sugars called
heptose
Which monosaccharides are most common
Hexose (6C)
How many asymmetric centers does hexose have?
4, 16 stereoisomers, Most are D isomers
3 most abundant hexose
D-glucose, D-mannose and D-galactose
What are the 2 tetrose aldose
2, Erythrose and threose
What are the 5C aldose
4, Ribose, arabinose, xylose, lyxose
What are the 6C sugars
8, allose, altrose, glucose, mannose, gulose, idose, galactose, talose
D-Erythrose
4C, OH like a E
D-Threose
4C, Left then right
D-Ribose
5C, All right side
D-arabinose
5C, Left right right
D-xylose
5C, Cris-cross right left right
D-lyxose
5C, Like arab, left left right
D-Allose
6C, All right
D-altrose
6C, top carbon left, the rest are right
D-Glucose
6C, La li la la
D-Mannose
6C, nn, so its 2 pairs, left left right right
D-gulose
6C, lose, almost the last Right right left right
D-Idose
6C, Reciprocate to say I do, left right left right
D-Galactose
6C, Like a galaxy edge, u shape, Right left left right
D-Talose
6C, All left except for for last
What are epimers
configuration around one carbon
Which hexose are epimers
D-mannose, D-glucose, D-galactose
What happens when hexose cyclize
Forms pyranose ring
How can monosaccharides be modified
Addition of chemical groups (GalNAc)
What is the fisher projection?
Like a fishing rod
What is the haworth perspective
Cyclic, Right is down
How are disaccharide called and formed
Glycosidic bonds, condenses the OH group and eliminate H2O
What are alpha linkages in disaccharides
Alpha is OH down
Whare beta linkages in disaccharides
Beta is OH up
What are the rule of glycosidic linkages regarding the OH group
Always involve C-1 of the left sugar(first)
What large polymeric structures called
Polysaccharides
Examples of unbranched homopolysaccharides
Cell wall (cellulose) and chitin for animals (exoskeleton)
What can branched carbohydrates used for
Starch (plants) and glycogen (animals)
What linkage does the branch point of carbohydrates have
alpha-1,6 glycosidic bond
What bond does unbranched glycogen have
alpha 1,4 linkages
What are the ends of the oligosaccharides
Nonreducing sugar (left), reducing sugar (right) Side with OH beside the O can be further reduced
How do you determine sugar concentration?
By measuring CuO2 (red) after adding Cu2+(blue) (used to determine blood glucose levels) Benedict’s solution copper citrate
What linkage are cellulose
glucose residues linked by Beta 1,4 glycosidic bonds
How are cellulose so stable
Stabilized by H bonds, result in long flat molecule, chains can form interchain hydrogen bonds
What is the structure of chitin
linear homopolymer of N-acetylglucosamine residues
similar to cellulose- only difference is the presence of an acetylated amino group at C-2
What is the structure of glycogen and starch (storage polysaccharide)
alpha 1,4 linkage, open helix structure ( Provides an accessible store of sugar )
What are carbohydrate groups that are covalently attached to many proteins
Glycoproteins, short oligosaccharide, function in recognition
How are carbohydrate linked to proteins
Via asparagine residue (N-glycans)
Via Serine or Threonine residues (O-glycans)
What enzymes are responsible for oligosaccharide assembly
Glycosyl (sugar) transferase
Nucleotide-monosaccharide (e.g. UDP-Glc)
+ Acceptor (carbohydrate)
—>
monosaccharide-Acceptor + nucleotide
monosaccharide is transferred from the nucleotide sugar to the non-reducing end of the carbohydrate acceptor
synthesis of the disaccharide lactose
β1,4 galactosyltransferase
UDP-Gal + Glc (Acceptor) —> Gal β1,4 Glc + UDP
What are the Human ABO blood groups
carbohydrate antigens
What are the ABO blood group antigens
glycosphingolipids
What is the oligosaccharide antigens of A antigen
GalNAc
What is the oligosaccharide antigens of B antigen
Gal
How many gene control the synthesis of ABO blood groups
one
What does the ABO blood group gene encode
glycosyltransferase (enzyme)
What does glycosyltransferase (enzyme) do
synthesis of particular oligosaccharides (high specific)
Where does specific residue connected to in the antigen?
C2 of the terminal galactose
How are antibodies produce?
occur naturally in individuals
What antigen does AB blood have
Both A and B
What antibodies does O blood have
None
What does antibodies do in blood
Antibodies will cross link the “foreign” red blood cells (agglutination)
What Does Lectins do
recognise carbohydrates
What is C-type lectins
Calcium binding lectins
What does calcium in c-type lectin do
acts a bridge between the protein and the sugar through direct interaction with sugar hydroxyl groups
Example of C-type lectins
Selectins
What is the role of selectins
- Are involved in cell-cell adhesion
* Bind white blood cells to sites of injury and allow movement of cells from blood stream to site of infection
How does most virus attach to host cell
vio carbohydrate
How does white blood cell binding to site of inflammation?
Selectin binding followed by integrin binding
How does virus bind to cell surface
Binds to the receptors( may be carbohydrates)
Where does influenza virus binds to
recognizes sialic acid residues present on cell surface glycoproteins
What is the anti-flu drug
relenza, is a sialic acid analogue
How does RELENZA work
inhibits the enzyme NEURIMINIDASE from flu virus to prevent virion from releasing, which halt viral replication
What is the Reaction between the CHO group at C-1 and the OH group at C-5 linkage called
hemiacetallinkage
Percentage of β-D-glucopyranose that exist
64%
How does GLUT1 transport glucose
Central polar region allowing the Glucose interactions (shielded from the hydrophobic environment of the bilayer core)
How does GLUT1 move?
Ligand bound occluded when glucose enter, then inward open, outward open when glucose goes through after ICH attach the ligand binding
What is the mid point of the transporter graph called
Kt (analogous to Km (enzyme))
Where is GLUT1 found and what it is used for
everywhere, basal glucose uptake
Where is GLUT2 found and what it is used for
Liver, pancreatic islets, intestine
In liver and kidney, removal of excess glucose from blood
In pancrease, regulation of insulin release
Where is GLUT3 found and what it is used for
Brain(neuronal), testis (sperm)
Basal glucose uptake
Where is GLUT4 found and what it is used for
Muscle, fat, heart
Activity increased by insulin
What is insulin for
Prevent glucose in blood to going too high
