carbs Flashcards
what are carbohydrates made up of
carbon, hydrogen and oxygen
what are the functional groups of carbohydrates?
carbonyl group (C=O) and hydroxyl groups
what is the molecular formula of glucose?
C6H12O6
what is the general formula for monosaccharides?
(CH2O)n where n = 3/4/5/6/7
what are 3 important uses of monosaccharides
energy sources to produce ATP during cellular respiration
building blocks to synthesise larger carbs
raw material for synthesis of other organic molecules
what are the 2 groups a carbonyl group could be?
aldehyde group (H-C=O) or a ketone group (C=O)
aldehyde groups are easily oxidised to carboxylic acids so do-monosaccharides are strong reducing agents
what is an anomeric carbon?
carbon that is bonded to TWO oxygen atoms
where does the hydroxyl group bonded to anomeric carbon lie in alpha glucose?
the hydroxyl group lies below the plane of the ring
where does the hydroxyl group bonded to anomeric carbon lie in beta glucose?
the hydroxyl group lies above the plane of the ring
how are disaccharides formed?
two monosaccharides are joined by a glycosidic bond during a condensation reaction resulting in the loss of a water molecule
what is a glycosidic bond?
the bond formed between the anomeric carbon of one sugar unit and another carbon on the other sugar unit
what are the TWO ways hydrolysis (break down) of a disaccharide can occur?
- incubation with dilute acid at 100C
- incubation with an enzyme
what are the monosaccharides that make up maltose, sucrose and lactose?
maltose: glucose + glucose
sucrose: glucose + fructose
lactose: glucose + galactose
what monomer is starch made up of
ONLY alpha glucose
starch consists of unbranced amylose and branced amylopectin, both of which are made up of glucose
what monomer is amylose made up of and what bond are involved?
alpha glucose
alpha (1,4) glycosidic bonds
what is the structure of amylose?
amylose forms a compact helical structure. there are 6 glucose units per turn in the helix
since amylose is bulky, it is poorly soluble in water and doesn’t exert osmotic influence in the cell
what monomer is amylopectin made up of and what bonds are involved?
alpha glucose
alpha (1,4) glycosidic bonds and alpha (1,6) glycosidic bonds
alpha (1,6) glycosidic bonds causes amylopectin to be branched
what are the advantages of amylopectin and glycogen being branched?
- the many branch ends allow a large number of enzymes to act on it at any one time so it is easily hydrolysed
- extensive branching causes amylopectin and glycogen to be highly compact
(i think) amylopectin is more compact than amylose
what monomer is glycogen made up of and what bonds are involved?
alpha glucose
alpha (1,4) glycosidic bonds and alpha (1,6) glycosidic bonds
alpha (1,6) bonds occur more frequently in glycogen than in amylopectin - so glycogen is more compact than amylopectin
what monomer is cellulose made up of and what bond is involved?
beta glucose
beta (1,4) glycosidic bonds
what is the effect of cellulose having alternate monomers inverted?
cellulose is long, unbranched and a straight chain
how is the cellulose polymer formed?
- cellulose chains run parallel to each other. OH groups project outwards from each chain
- extensive hydrogen bonds form between the OH groups, establishing rigid cross links between chains
- the cross-linked cellulose chains associate in groups, forming microfibrils
- microfibrils associate with other non-cellulose polysaccharides and are arranged in larger bundles, forming macrofibrils
what property of cellulose accounts for its high tensile strength?
cellulose fibrils are laid down in different orientations in different layers of the plant cell wall, permitting the cell wall to withstand forces exerted in all directions
