Carbohydrates, lipids and water Flashcards
What is maltose?
disaccharide formed by condensation of two glucose molecules
what is sucrose?
disaccharide formed by condensation of glucose and fructose
what is lactose?
disaccharide formed by condensation of glucose and galactose
what are the two isomers of glucose
beta and alpha
what is glycogen and starch formed by
the condensation of alpha glucose
what is cellulose formed by
the condensation of beta glucose
what is a monomer
small units from which larger molecules are made
what is a polymer
molecules made from a large number of monomers joined together
what is a condensation reaction
joins two molecules together with the formation of a chemical bond and involves the elimination of a water molecule
what is a hydrolysis reaction
breaks a chemical bond between two molecules and involves the use of a water molecule
what are two groups of lipid
triglyceride and phospholipids
how is a triglyceride formed
condensation of one molecule of glycerol and three molecules of fatty acid
condensation reaction between glycerol and a fatty acid forms a what
an ester bond
what can the r group in a fatty acid be
saturated or unsaturated
what happens in a phospholipid that is different from a triglyceride
one of the fatty acids of a triglyceride is substituted by a phosphate-containing group
explain 5 properties water has that is important in biology
- a metabolite - water can be involved in metabolic reactions such as condensation and hydrolysis
- a solvent - allows metabolic reactions to occur and allows the transpor of substances
- high specific heat capacity - buffers changes in temperature
- large latent heat of vaporisation - provides a cooling effect
- cohesion - supports the formation of continuous columns of water. Produces surface tension which supports small organisms
what are organic molecules
molecules with carbon-carbon and carbon-hydrogen bonds
name 3 monosaccharides
glucose
fructose
galactose
name 3 disaccharides
maltose
lactose
sucrose
name 3 polysaccharides
starches
cellulose
glycogen
what does saccharide mean
sugar
whats the molecular formula for glucose
c6h12o6
what is formed when two monosaccharides join together in a condensation reaction
glycosidic bond
what is a polysaccharide
type of polymer formed by joining many monosaccharides (3+) together by condensation reactions
what is an example of a storage polysaccharide in plants
starch
explain 4 structure features of starch and how it helps its function
1)helical structure which makes it compact allowing many alpha glucose molecules to fit into a small area
2)branched structure which gives it a larger surface area allowing for faster enzyme action
3)large so it cant diffuse out of cells
4)insoluble so doesn’t affect water potential
explain 3 structure features of glycogen and how it helps its function
1)coiled making it compact allowing many alpha glucose molecules to be packed together
2)insoluble so doesn’t affect water potential
3)large molecule so it cannot cross the cell membrane and diffuse out of cells
give 3 ways glycogen has specific adaptations compared to starch
1)shorter chains
2)more highly branched
3)larger surface area
what is cellulose a polymer of
beta glucose
where is cellulose found
plant cell walls
where is the OH group in alpha glucose
below
where is the OH group in beta glucose
above
explain how celluloses structure helps its function
-Several chains of cellulose are joined together into layers by weak hydrogen bonds
-this forms microfibrils which wound together to form cellulose fibres
-these fibres provide rigidity/strength and support to the cell wall
what are the three different tests for carbohydrates
1)benedicts test for reducing sugar
2)benedicts for non-reducing sugar
3)iodine test for starch
name 5 reducing sugar
1)glucose
2)galactose
3)lactose
4)maltose
5)fructose
name a non-reducing sugar
sucrose
explain the benedicts test method for reducing sugar
1)add equal volume of benedicts solution and sample to a test tube
2)heat to 95 degrees
3)if there is a reducing sugar there will be a formation of a brick red precipitate
explain the benedicts test for non-reducing sugar
1)boil a fresh sample with hydrochloric acid for 5 minutes
2)neutralise the solution by adding sodium hydrogen carbonate
3)then follow the same steps as reducing sugar
why do you use hydrochloric acid for the non-reducing benedicts test
it hydrolysis the glycosidic bond to produce glucose and fructose which are both reducing sugars
what is the main role
of lipids
main component of the cell surface membrane
explain 3 other roles lipids have
source of energy- lipids provide twice as much energy as carbohydrates when they are oxidised
insulation- fats dont conduct heat well
protection- layer of fat surrounds organs
how is a triglyceride formed
one molecule of glycerol joined to 3 fatty acids by a condensation reaction which forms 3 ester bonds between the carboxyl group of the fatty acid and the hydroxyl group of glycerol
whats the difference between saturated and unsaturated fatty acids
saturated fatty acids have no double bonds between carbons. Unsaturated fatty acids have double bonds
explain properties of tryglycerides
-triglycerides are hydrophobic
-contain a lot of energy
-have a low energy:mass ratio making it excellen for storing energy(compact)
-release water when oxidised
explain the emulsion test for lipids
-add ethanol to sample and mix
-add water and mix
-if present a white emulsion will appear
how is a phospholipid formed
1 glycerol joins to 2 fatty acids and 1 phosphate group by a condensation reaction
how many bonds are in a:
1) triglyceride
2) phospholipid
1)3 ester bonds
2)2 ester bonds
what are the 2 different parts of a phospholipid called
-hydrophilic head
-hydrophobic fatty acid tail
explain the hydrophilic head in phospholipids
it is attracted to water, so it interacts with it. This is caused by the polar(charged) nature of the phosphate group
explain the hydrophobic tails in phospholipids
they are repelled by water and face away from it. This is because they are non-polar(not charged)
