Carbohydrates Flashcards
State the elements present in carbohydrates. (F)
- Carbon
- Hydrogen
- Oxygen
State the general formula of carbohydrates. (F)
Cn(H2O)n
Define the term “monosaccharide”. (F)
A single sugar molecule
Define the term “pentose sugar” and give an example. (F)
A monosaccharide composed of 5 carbons i.e. ribose
Define the term “triose sugar” and name an example. (S+C)
A monosaccharide composed of 3 carbons i.e. glyceraldehyde
Describe what is meant by a “furanose ring” and a “pyranose ring”. (S+C)
Furanose ring: a five membered ring with 4 carbon atoms and an oxygen atom
Pyranose ring: a six membered ring with 5 carbon atoms and an oxygen atom
Define the term “isomer”.
Structural variation between molecules with the same atoms.
Describe the difference between alpha- and beta-glucose. (F)
Alpha-glucose has the hydroxyl group on C1 below the carbon ring; beta-glucose has the hydroxyl group on C1 above the carbon ring
List the similarities between alpha-glucose and ribose.
- soluble in water
- composed of C, H and O
- contain -OH groups
List 3 examples of disaccharides and for each state which monosaccharides they are composed of. (F)
- maltose (two alpha-glucose molecules)
- sucrose (alpha-glucose and fructose)
- lactose (beta-glucose and galactose)
State the properties of glucose.
- polar
- water soluble
- sweeter than galactose
State the properties of fructose.
- polar
- water soluble
- sweeter than glucose and galactose
State the properties of galactose.
- polar
- water soluble
- sweet
State the properties of maltose.
- soluble
- less sweet than glucose
State the properties of sucrose.
- sweet
- soluble
State the properties of lactose.
- low solubility
- slow release of energy
Explain why alpha-glucose links together to form starch whereas beta-glucose links together to form cellulose.
Alpha-glucose has both -OH chains on C1 and C4 below the carbon ring, so it forms starch.
Beta-glucose has to rotate to link because the -OH on C1 and C4 are on opposite sides of the carbon ring, so it forms cellulose.
List the two different polysaccharides that make up starch. (F)
- amylose
- amylopectin
Explain why glycosidic bonds are called 1,4 or 1,6.
Glycosidic bonds are 1,4 when they occur between C1 and C4.
Glycosidic bonds are 1,6 when they occur between C1 and C6.
Explain how to calculate the number of glycosidic bonds in a carbohydrate given the number of monosaccharides it is made up from. (S+C)
number of glycosidic bonds = number of monosaccharides - 1
Describe the structure of a cellulose fibre.
Straight chain
State the properties of amylopectin.
- highly branched
- insoluble
- compact
State the properties of cellulose.
- insoluble
- forms fibres which are insoluble
State the properties of glycogen.
- highly branched
- insoluble
- compact
State the properties of amylose.
- compact
- insoluble
Relate the structural properties to the functions of amylopectin with reference to its solubility, size, bonding and presence of side chains. (F)
- insoluble so good for energy storage (doesn’t change water potential of a cell)
- large in size so good for energy storage
- has 1,4 and 1,6 glycosidic bonds so has many side chains (branched) so is good for energy storage and release
Relate the structural properties to the functions of amylose with reference to its solubility, size, bonding and presence of side chains. (F)
- insoluble so good for energy storage (doesn’t change water potential of a cell)
- large so good for energy storage
- has 1,4 bonds glycosidic bonds only and forms a helix with hydrogen bonds so good for energy storage (strong)
- no side chains present
Relate the structural properties to the functions of glycogen with reference to its solubility, size, bonding and presence of side chains. (F)
- insoluble so good for energy storage (doesn’t change water potential of a cell)
- large in size so good for energy storage
- has 1,4 and 1,6 glycosidic bonds so has many side chains (branched) so is good for energy storage and release
Relate the structural properties to the function of cellulose with reference to its solubility, size, bonding and presence of side chains. (F)
- insoluble so doesn’t affect water potential of a cell
- large because fibres are formed, which make it strong
- 1,4 glycosidic bonds only so it is straight chained and strong
- no side chains
Define the term “disaccharide”. (F)
Two sugar molecules joined together
Define the term “polysaccharide”. (F)
A polymer made of many sugar molecules joined together
Define the term “hexose sugar” and give an example. (F)
A monosaccharide composed of 6 carbons i.e. glucose
List the differences between alpha-glucose and ribose.
- A is a hexose sugar; R is pentose sugar
- A is found in starch, cellulose etc.; R is found in RNA and ADP
- A is used for energy storage; R is used in mRNA coding for proteins
State the functions of glucose.
Energy release
State the functions of glucose.
Energy release
State the functions of glucose.
Energy release
State the functions of maltose.
Intermediate step in forming starch from glucose in plants
State where maltose occurs.
Plants
State the functions of sucrose.
Makes fruit sweet
State where sucrose occurs.
Fruit
State the functions of lactose.
Slow energy release for babies
State where lactose occurs.
Milk
State the functions of amylopectin.
Energy storage and release
State the functions of cellulose.
- make cell walls
- fibre for digestive system
State the functions of glycogen.
Energy storage and release
State the functions of amylose.
Energy storage
