molecules of life N Flashcards
amino acid
a monomer which makes up protein
has a central carbon atom bonded to a carboxylic acid group, an amino group a hydrogen atom and an R group
condensation reaction
a chemical procss when two monomers combine to form a polymer eliminating a simple substance - usually water
covalent bond
bond between two non metals that share a pair of electrons
hydrolysis
breaking down of large molecules into smaller ones by the addition of water molecules
monomer
a single unit which is used to form larger more complex molecules
nucleotide
a compound consisting of an organic base and ribose sugar linked to a phosphate group
they form monomers of nucleic acids such as dna
organic molecule
molecules containing carbon which can be found in living things
- carbohydrates
- proteins
- lipids
- nucleic acids
what elements are common to all forms of life
carbon, oxygen and hydrogen
3 examples of polymers
polysaccarides
protein
dna/rna
3 hexos monosaccarides
glucose
fructose
galactos
all have molecular formula : C6H12O6
type of bond formed when monosaccarides react
1-4or 1-6 glycosidic bonds
3 disaccarides and how they form + their molecular formula
- glucose + glucose = maltose
- glucose + galactose = lactose
- lucose + fructose = sucrose
all have molecular formula C12H22011
molecular formula of sucros / maltose/ lactose
C12H22O11
3 things
starch
- storage molecule of alpha glucose in plant cells
- insouluble - so osmotic effect in cells
- large - does not diffuse out of cells
2 properties of starch and their uses
- large - so it doesnt diffuse out of plant cells
- insoluble - so no osmotic effect in cells
amylose
- 1-4 glycosidic bonds
- long unbranched chain of alpha glucose
- coiled shape with intermolecular h bonds making it compact
found in starch
amylopectin
- 1-4 and 1-6 glycosidic bonds
- branched - increases surface area for enzyme action for hydrolysis into glucose - glucose can be released fast
found in starch
5 things
glycogen
- main storage molecule of glucose in animals - also found in plants
- 1-4 and 1-6 glycosidic bonds
- insoluble - no osmatic effect
- coiled shape with intermolecular hydrogen bonds - compact
- branched - many terminal ends increase surface area for hydrolysis
why is cellulose needed in cell walls
prevents bursting under turgor pressure and holds up stem
4 things
cellulose
- polymer of beta glucose which reinforces cell walls
- 1-4 glycosidic bonds
- cellulose chains linked by H bonds forming microfibrils
- H bonds between cellulose chains make microfibrils strong and flexible
uses of starch
storage molecule for excess glucose in plants as it is too large to exit cell and insoluble so wont effect water potential
starch is hydrolised to release glucose for respiration
uses of cellulose
major structoral component in plant cells allowing cells to become turgid and providing support
uses of glycogen
used to store excess glucose in muscle and liver cells which can be used as an energy source when hydrolised to release glucose for respiration (i.e during exercise)
test for starch
iodine
iodine test
- tests for starch
- addiodine dissolved in potassium iodide to sample
- if starch present change from browny orange - bluey black
why is being insoluble good for storage
-doesnt affect water potential so water doesnt enter cells via osmosis causing them to swell
Glycerol
a molecule which combines 3 fatty acids to form triglycerides
its a 3 carbon chain with 3 hydrocyl groups
hydrophillic
section of a molecule attracted to water
hydrophobic
section of molecule repulsed by water
Test for lipids
- Dissolve solid sample in ethanol
- add equal volume of water and shake
- positive - milky white emulsion
How triglycerides form
Condensation reaction between 1 glycerol & 3 fatty acids forms ester bonds
Compare saturate and unsaturated fatty acids
saturated
- contain only single bonds
- straight chain molecules
- higher melt point - solid at room temp
- found in animal fats
unsaturated
- contain c=c double bonds
- kinked molecules - have fewer contact points
- found in plant oils
How is the structure of triglycerides good for their function
- high energy - mass ratio = high calorific value - energy storage
- insoluble hydrocarbon chain - no effect on water potential + used for water proofing
- slow conductor of heat = thermal insulation
- less dense than water - buoyancy of aquatic animals
Structure of phospholipids
Glycerol backbone attached to 2 hydrophobic fatty acid tails and 1 hydrophilic phosphate head
How is structure of phospholipids used
- forms phosopholipid bilayer in water - component of membranes
- tails can splay outward for waterproofing
What type of molecules lipids
Macromolecules - not polymers
Why is water a polar molecule
- o is more electronegative than H so attracts e- more strongly
- o is slightly negative charge
- h has a slightly positive charge
Properties of water
- metabolite
- high specific heat
- high latent heat
- strong cohesion
- solvent
Why and is water important to living organisms
- solvent during metabolic reactions - hydrolysis
And condensation - enables temperature management in organisms
- cohesion in transpiration stream
Why and is water important to living organisms
- solvent during metabolic reactions - hydrolysis
And condensation - enables temperature management in organisms
- cohesion in transpiration stream
What molecules in glucose bond in a condensation reaction
Two OH bond to form H20 leaving one oxygen for the glycosidic bond
Example of a non reducing sugar
Sucrose
Reducing sugar
Sugar that can be used as a reducing agent includes all monosaccharides and some disaccharides
Non reducing sugar
Sugar that can’t be used as a reducing agent I.e sucrose
Example of reducing sugar
Any monosaccharide (some disaccharides I.e maltose)
Test for reducing sugars
Benedict’s
Method to test for reducing sugars
- add 2cm³ of food sample in liquid form or aqueous
- add 2cm³ of Benedict’s reagent (copper II sulphate)
- heat in a water bath for five minutes
- positive - a brick red precipitate will form ( or orange / yellow/ green)
- negative - solution will remain blue and no precipitate will form
Test for non reducing sugars
- add 2cm³ of dilute hcl to food sample and place test tube in a water bath for 5 minutes so it can hydrolyse the disaccharides and polysaccharides
- add an alkali ( I.e sodium hydrogen carbonate) to neutralise the solution as Benedict’s won’t work in acidic conditions
- use ph paper to ensure it’s neutralised
- add 2cm³ of Benedict’s (copper II sulphate)
- if positive a brick red precipitate forms
Benedict’s reagent
- Copper II sulphate
- used to test for reducing sugars
- don’t work in acidic conditions
Maltose
Disaccharide of aplastic glucose x2
Sucrose
Disaccharide of glucose and fructose
Non reducing sugar
lactose
Disaccharide of galactose and glucose
Glycogen
- polysaccharide of alpha glucose
- main energy storage molecule in animals
- 1,4 and 1,6 glycosidic bonds
- branched with many terminal ends increasing surface area for reactions (I.e hydrolysis)
- compact - maximising amount of energy that can be stored
- insoluble so won’t affect the water potential no osmotic effect
Starch
- polysaccharide of alpha glucose
- formed by amylose (unbranched) and amylopectin (branched)
- 1,4 and 1,6 glycosidic bonds
- compact so it can be transported easily and more energy can be stored in a small space
- insoluble solution don’t affect water potential so don’t diffuse out
