carbohydrates Flashcards
(26 cards)
carbohydrates functions
- respiratory substrate in cells
- structural components in plasma membranes and cell walls
monosaccharides
- single sugar
- glucose, fructose, galactose
alpha glucose and beta glucose difference
alpha - OH is in the bottom
beta - OH is on the top
alpha and beta glucose
- isomers
- same atoms but arranged differently
monosaccharides functions
they can be used as respiratory substrates to produce energy for reactions within the body
polysaccharides functions
used as energy storage (glycogen and starch) or build structure (cellulose in cell wall)
disaccharides
- two monosaccharides will bond together through a condensation reaction where a bond is formed and a molecule of water is released
- a glycosidic bond is formed
disaccharides examples
glucose + glucose = maltose
glucose + fructose = sucrose
glucose + galactose = lactose
(1,4) glycosidic bond
- carbon 1 is bonded to carbon 4 on the two molecules
- this is the bond in straight chain polysaccharides
branching
- these are parts of the polysaccharide that branch off the main polysaccharide chain
- the bond which cause branching are (1,6) glycosidic bonds
polysaccharides
a long chain of monosaccharides
3 main polysaccharides
- glycogen
- cellulose
- starch
glycogen function
used as an energy stored molecule in animals
glycogen - location
found in the liver and muscle cells
glycogen - structure
- made out of a long chain of alpha glucose
- branched, helps it to be broken down more quickly and for more of it to fit into a given area
why does branching help glycogen to be broken down more quickly?
- the glycogen will be broken down using enzymes that will perform hydrolysis reactions to break the bonds
- if the molecule is branched, a lot more enzymes are able to act on the ends of chains at a given time, meaning that multiple hydrolysis
starch - function
- energy storage molecule in plants
- made out of alpha glucose
starch - composed of two subunits
- amylose: long, unbranched chains (1,4) glycosidic bonds which are coiled (more compact)
- amylopectin: branched chains (1,4) & (1,6) glycosidic bonds and can only be broken down more quickly by enzymes doing hydrolysis reactions
cellulose - function
used to make a cell wall
why is cellulose important to make a cell wall?
the cell wall is important for giving strength to the cell and stopping it from bursting or shrivelling
cellulose - structure
- long chains of beta glucose
- these long chains are bunched together with cross-lines between them to make them extra long
biochemical test for carbohydrates
benedicts test
Benedicts test
- reducing sugars (monosaccharides)
- orange to brown = positive
how to carry out the Benedicts test
- non-reducing sugars (sucrose)
- hydrochloric acid and sodium hydrogen carbonate solution
- then Benedict’s test
- needs to hydrolyse non-reducing sugar (acid) then neutralise pH
