BGM1002/L11 Carbohydrates II Flashcards
What is maltose?
Disaccharide of glucose + glucose
Major product generated from starch digestion
What is lactose?
Disaccharide of glucose + galactose
Milk sugar
What is sucrose?
Disaccharide of glucose + fructose
Transport form of carbohydrate from plants (table sugar)
Name 2 important energy storage molecules in the human body.
Starch
Glycogen
What types of glycosidic bond exist in starch and glycogen?
Alpha-1,4
Alpha-1,6
Where can starch be found? (2)
Plants
Human food sources
Where is glycogen found?
Animals
Which end of a polysaccharide is the reducing end?
Terminal in which C1 is unattached
Which end of a polysaccharide is the non-reducing end?
The terminal in which C1 is involved in a glycosidic bond
Cannot reduce other molecules
What causes some polysaccharides to twist into a helical structure?
Alpha-1,4-glycosidic bonds
Why is a helical structure favourable for sugars? (2)
More compact
Easily accessible
Where is cellulose found?
Plant cell walls
What causes cellulose chains to be planar?
Beta-1,4-glycosidic bonds
How do cellulose chains pack together?
Hydrogen bonds between chains
Where is peptidoglycan found?
Bacterial cell walls
What is a glycoconjugate?
A carbohydrate covalently bonded to other molecules e.g., proteins and lipids
Give a function of glycolipids.
Receptors for cell recognition
What are N- and O-linked glycoproteins
N- nitrogen-linked
O- oxygen-linked
What 3 functions does N-glycosylation have?
Protein folding
Stability
Cell recognition
What are N-linked glycoproteins attached to?
Amide group of asparagines
What are O-linked glycoproteins attached to?
Hydroxyl group of serine or threonine
What kind of glycosylation plays a role in mucins?
O-glycosylation
What is a glycosaminoglycan?
Protein attached via O-linkage to polysaccharides
Give 2 functions of proteoglycans.
Joint lubricants
Structural components of ECM
Mediate adhesion of cells to ECM
Bind factors that stimulate cell proliferation
Which component of proteoglycans determines function?
GAG
What are proteoglycans composed of?
Disaccharide repeats of amino sugar and uronic acid sugar
What is the function of glycotransferases?
Transfer of sugars from nucleotides onto other molecules
What is the initial step of a viral infection?
Binding of spike protein surface to human angiotensin-converting enzyme 2 (ACE2) receptor
What is passive ‘antibody shielding’?
Antibodies bind to spike protein and ‘block’ interaction between virus and ACE2
What role do N-glycans play in RBD?
They stabilise the ‘up’ state of spike protein
