biological molecules (carbohydrates, lipids and proteins) Flashcards
monomer
a small molecule that binds to many other identical molecules to from a polymer
polymer
a large molecule made up of many monomers bonded together
covalent bond
a strong bond formed when electrons are shared between 2 atoms
condensation reaction
- 2 hydroxyl groups, line up alongside each other
- 1 combines with an H atom to form on H2O
hydrolysis reaction
- a water molecule, is used to split the disaccharide
- breaks the glycosidic bond
what elements do all biological molecules contain
carbon, hydrogen and oxygen
name a non - reducing sugars
sucrose
name 3 reducing sugars
- lactose
- maltose
- cellubiose
name 3 reducing sugars
- lactose
- maltose
- cellobiose
what is a qualitative test
positive or negative results (tells use whether a particular substance is present)
what is a quantitative test
tells us how much (concentration) of a substance is present)
are polysaccharides more or less soluble in water than monosaccharides
less soluble in water
what is the structure of amylose?
- straight chain structure
- alpha - glucose molecules held together by 1,4 glycosidic bonds
- repetition of 1,4 glycosidic bonds, causes amylose to coil into a helix
what is the structure of amylopectin?
- similar to amylose, but can also from 1,6 glycosidic bonds
- forms branches, that allows amylase (enzyme) to break of molecules of glucose when the are require
- (they do contain 1,4 glycosidic bonds as well as the 1,6)
what is the structure of cellulose
- each adjacent beta - glucose molecule, will rotate 180 degrees in order to from the straight chain.
- this allows it to from a straight chain glycosidic bond
what is the most common type of lipids
triglycerides
what are the two main properties of lipids
- insoluble in water (non - polar)
- high in energy -> rich in C-H bonds ( higher than carbohydrates)
what is a condensation reaction
occur when 2 molecules, are joined with the removal of water -> forms a covalent bond
what is a hydrolysis reaction
splitting, 2 molecules apart with the addition of water -> breaks a covalent bond
what is the monomer of carbohydrates
monosaccharides
what is the polymer of carbohydrates
polysaccharides
what is the monomer of proteins
amino acids
what is the polymer of proteins
polypeptide
what is the definition of a polar molecule
a molecule with regions of slight positive charge and slight negative charge.
what will happen if something is less dense than water for example a frog
it will simply float on the surface of the water.
what bonds do amino acids form, when the interact with the water,
hydrogen bond
why must lipids not be filtered, with filter paper, when doing a food test
the lipids, could stick to the filter paper
what is a reducing sugar
reducing sugars, can donate an electron to another molecule
what are the properties that water has, due to hydrogen bonds?
- liquid at room temperature
- density
- solvent for molecules
- water and non polar molecules
- cohesion and surface tension
- high specific capacity
- high latent heat of vaporisation
- water as reactant (not directly linked to hydrogen bonds)
what are the properties, of monosaccharides
- sweet taste
- soluble in water (polar solvent)
- insoluble in non - polar solvents
what are isomers
molecules, with the same molecular formula, but a different structural formula.
what is the structure of Alpha - Glucose
what is the structure of Beta - Glucose
what are the properties of disaccharides
- taste sweet
- soluble in polar solvents
- some are reducing (donate electrons)
give an example of a reducing sugar and an example of a non - reducing sugar
- maltose (reducing)
- sucrose (non - reducing)
what is a reducing agent
- donates/provides electrons to another molecule
what is a oxidising agent
accepts electrons from another molecule
oxidation is …
reduction is …
- loss of electrons
- gain of electrons
all monosaccharides are reducing sugars
true
what is a polysaccharide
a molecule, which consists of hundreds or thousands of monosaccharides, which are joined by condensation reactions, resulting in the formation of glycosidic bonds
why are glycogen and amylopectin branched
- more compact
- also offers the chance, for lots of glucose molecules to be snipped off by hydrolysis at the same time, when lots of energy is required.
describe, what happens in the formation of Starch
- amylose helix, becomes tangled in amylopectin branches
- mixtures of amylose/amylopectin build up
describe the structure of Glycogen
- very similar to amylopectin, but it is more branched (more frequent 1,6 glycosidic bonds)
- more compact
- insulin, causes alpha glucose molecules, to condense
what are the properties of lipids
- insoluble in water (non - polar) - but are soluble in organic solvent e.g. - ethanol
- high in energy (higher than carbohydrates)
what is a unsaturated fatty acid
- this means that there is one or more carbon double bond
- this causes the molecule to kink, thus spacing it out more.
what is a saturated fatty acid
- only contains single carbon bonds
what is the structure of a triglyceride
- a glycerol backbone, connect to 3 fatty acid molecules, via 3 carbon bonds.
how do the fatty acid molecules, attach to triglyceride
- they attach via a condensation reaction
what do we call the bond that is formed between each fatty acid and hydroxyl group
- an ester bond
what are the functions of triglycerides
- energy source
- energy store
- insulation (heat insulator or electrical insulator
- buoyancy
- protection
what are waxes composed of
- waxes are composed of large alcohols, attached to fatty acids
how do we test for lipids
- the emulsion test
- add the mixture, to ethanol shape and see if a emulsion layer (precipitate) has formed, to signify the presence of a lipid
what are phospholipids
they are like a triglyceride, except one of the fatty acids is replaced by a phosphate group.
what is cholesterol
- cholesterol, is a steroid alcohol
- consists of 4 carbon based rings or isoprene units
- in animals, it is made in the liver
what are the properties and functions of cholesterol
- helps to regulate the fluidity of the cell membrane
- at high temperatures, it stabilises the membrane and raises the melting point.
- at low temperatures it intercalates between the phospholipids and prevents clustering
what are the functions of proteins
- essential component of phospholipid bilayer
- all enzymes are proteins
- antibodies are proteins
- haemoglobin
- collagen
- keratin
- structural role
what is the structure of an amino acid
what is primary protein structure
sequence of amino acids, held together by peptide bonds
what is the secondary protein structure
folding of amino acid chain into alpha helix or beta pleated sheet, due to hydrogen bonding between amino acids.
what is the tertiary protein structure
folding of the secondary structure, to form a precise 3D shape.
what is the quaternary protein structure
a protein, which is made up of 2 or more polypeptide chains.
what are the 5 Cations
- calcium
- sodium
- potassium
- hydrogen
- ammonium
what are the 5 Anions
- nitrate
- hydrogen carbonate
- chloride
- phosphate
- hydroxide
how do you test for non reducing sugar?
- carry out a normal sugar test and get a negative result
- take some of this sample, and boil it with hydrochloric acid (use anti bumping granules)
- cool the solution and then add sodium carbonate to neutralise the solution,
- check using pH paper that the solution has been neutralised.
- then carry out the reducing sugar test again and you should have positive result in the form of a brick red precipitate if non - reducing sugars are present.
why do we use anti bumping granules in the non reducing sugar test?
To prevent the formation of large gas bubbles that cause violent boiling.
why do we filter the red precipitate after the benedicts test
in order to form a supernatant solution, that we can use in order to measure the light absorbance on a colorimeter and we can compare this to known values, in order to see the concentration of the solution.
