carbohydrates Flashcards
what is a monosaccharide?
a single sugar unit
give 2 examples of monosaccharides
- ribose
- glucose
give 3 examples of disaccharides
- maltose
- lactose
- sucrose
give 3 examples of polysaccharides
- starch
- cellulose
- glycogen
how are carbohydrates bonded?
glycosidic bond
what makes glucose a hexose monosaccharide?
contains 6 carbon atoms
state the difference between alpha and beta glucose
in alpha glucose, the right hand carbon atom has hydrogen on top and hydroxide on the bottom
- the other way round in beta
why is glucose soluble?
due to hydrogen bonding
state 4 characteristics of glucose
- small
- soluble
- easily transported
- easily oxidised
describe how a di/poly saccharide forms
- hydroxyl groups interact
- glycosidic bond forms between carbon 1 and carbon 4
- water is released
- condensation reaction
describe amylose
- linear
1-4 glycosidic bonds - soluble
- helix chain (resistant to digestion, slow energy release)
- alpha glucose
describe amylopectin
- branched
- 1-4 and 1-6 glycosidic bonds
- insoluble
- faster glucose release
describe the structure and function of starch
- made of amylose and amylopectin
- joined by glycosidic bonds
- storage
describe the structure and function of glycogen
- alpha glucose
- insoluble (doesn’t affect cell’s water potential)
- branched
- free ends so molecules can easily be added/removed
- storage
- many in liver/muscle for respiration
- glucose storage in animals
describe the structure and function of cellulose
- insoluble
- beta glucose
- alternate monomers flipped
- linear
- hydrogen bonds form microfibrils which form strong fibres for cell walls
- 1-4 glycosidic bonds
- can stretch
- matrix provides strength
- fibres are permeable so water and solutes reach cell surface membrane
state and explain 2 ways in which the glucose molecule is well suited to its function (2)
it is soluble so can be easily transported around the cell. it is easily oxidised which means it can provide energy quickly.
agarose forms a complex carbohydrate - agar. agar is used as a growth medium for bacteria. suggest why bacteria cannot break down the agarose.
bacteria does not have the correct enzymes
explain why glycogen makes a good storage molecule (3)
- branched structure
- takes up less space
- easy to break down
- insoluble so does not affect cell’s water potential
