Carbohydrates 1 Flashcards
Why are carbohydrates described as ‘highly oxidisable’?
Carbs have high energy H atom-association
How are carbs stored in animals and plants respectively?
Animals - glycogen
Plants - Starch
Name the three most important hexose sugars in human biochemistry
Glucose, galactose and fructose
How are disaccharides formed?
Formed from monomers that are linked by glycosidic bonds
What is a glycosidic bond?
Covalent bond formed when hydroxyl group of one monosaccharide reacts with the anomeric carbon of another monosaccharide
What is an anomeric carbon?
It is the carbon on the principle carbon on the glucose residue- the only residue that can be oxidised
What are the three most important disaccharides in human biochemistry?
Maltose, Lactose and sucrose
In what ways can we distinguish between polysaccharides?
- Their recurring monosaccharide units
- Length of their chains
- Types of bonds linking the monosaccharides
- Amount of branching the have
Define a homopolysaccharide
Polysaccharide made of a single monosaccharide species
Define a heteropolysaccharide
Polysaccharide made of two or more monomer species
Describe the structure of starch
Contains two types of glucose polymer (amylose and amylopectin)
Describe the proportion of reducing ends in starch
Low
Describe the structure of glycogen
Polymer of glucose containing 1,4-glycosidic and 1,6-glycosidic bonds (making it extensively branched)
Why store glucose as a polymer?
- Compactness
- Many non-reducing ends allows quick synthesis and catabolism
- Form hydrated gels (partial precipitation) therefor don’t effect osmolarity
What are glycoproteins?
Proteins with covalently attached carbohydrates
What are some functions of glycoproteins?
- Increase protein solubility
- Influence protein folding/configuration
- Protect protein from degradation
- Act as communication between cells
Glycosaminoglycans (GAGs) are made of what?
Un-branched polymers made from repeating units of hexuronic acid and an amino-sugar
Where are GAGs found?
Mucous and synovial fluids
How are proteoglycans formed?
From GAGs covalently attaching to proteins
Where are proteoglycans found?
Found on the surface of cells or in-between cells in the extracellular matrix
Why types of tissues are proteoglycans found in?
Connective tissues
Where in the body are glycoproteins usually found?
Outer plasma membrane and extra-cellular matrix. Can also be found in blood and within cells in the secretory system (Golgi complex)
What are Mucopolysaccharidoses?
A group of genetic disorders caused by the absence or malfunction of enzymes required for the digestion of GAGs
Describe the natural history of a mucopolysaccharidoses disease
Over time, GAGs build up in connective tissue, blood and other cells - these deposits cause damage
What are some of the related pathologies of Mucopolysaccharidoses?
Severe dementia, heart problems, inflamed bones and joints
