2.1.2 biological molecules Flashcards
why is collagen described as having a quaternary structure rather than tertiary?
it has 3 polypeptide chains in each molecule so forms a triple helix structure
what chemical elements make up carbohydrates?
carbon, hydrogen , oxygen
what chemical elements make up lipids?
carbon, hydrogen , oxygen.
what chemical elements make up proteins?
carbon , hydrogen, oxygen ,nitrogen, sulphur
what chemical elements make up nucleic acids?
carbon , hydrogen, oxygen, nitrogen, phosphorus
- give 3 examples of fibrous proteins. ( beginning with k,c and e)
- where are they found?
- keratin (found in hair and nails)
- collagen (found in skin and tendons)
-elastin ( found in connective tissue and skin)
how do you calculate the Rf value for chromatography?
distance moved by solute / distance moved by solvent
describe is the test for proteins?
what will you see for a positive test?
- biuret test
- add your testing sample to a test tube.
-add an equal amount of sodium hydroxide.
-then add a few drops of copper surface and mix.
-if positive, the solution will turn purple
-if negative solution will stay blue
what is the test for non-reducing and reducing sugars?
what will you see for a positive result?
- benedict’s test
- add benedict’s reagent to a test tube.
- add your test sample
- put in a water bath of 70°c for 30 minutes
- if positive, it will be a brick red colour.
-if negative it will stay blue
what is the test for lipids?
what will you see if it’s a positive test?
- emulsion test
- add 2cm3 of test sample to a test tube
- add 5cm3 of cold ethanol to test tube and mix
- add 5cm3 of distilled water
- if positive, the solution will turn cloudy
- if negative the solution will stay clear
what is the test for starch?
what will you see if it’s a positive result?
- iodine test
- add your sample to a spotting tile
- add a few drops of iodine to the sample
- if positive, the sample will turn blue-black
- if negative it will remain orange-brown
what is the functions of fibrous proteins?
what properties do fibrous proteins possess?
what’s the general structure of an amino acid?
what’s the function of collagen?
- provide mechanical strength
what’s the function of elastin?
-
what’s the function of keratin? (2)
- provides mechanical protection
- provides an impermeable barrier to infection and water-borne pollutants
what ions has the symbol NO3-?
nitrate
what ion has the symbol Ca²+?
calcium ions
what ion has the symbol Na+?
sodium ion
what ion has the symbol OH-?
hydroxide ion
what is the symbol for phosphate ion?
PO43-
what ion has the symbol H+?
hydrogen ions
what ion has the symbol NH4+?
ammonium ion
what ion has the symbol HCO3-?
hydrogen carbonate ion
what ion has the symbol K+?
potassium ion
what ion has the symbol Cl-?
chloride ion
what is the primary structure of proteins?
the sequence of amino acids in a chain bonded by peptide bonds
what determines the primary structure of a protein?
it’s dna
what is the secondary structure of a protein?
what is the tertiary structure of a protein?
further folding of the protein forming additional bonds between the R groups
what are the 4 additional bonds in the tertiary structure and where do they take place?
- hydrogen bonding between R groups
- disulphide bonds between cysteine amino acids
- ionic bonds between charged R groups
- hydrophobic interactions between non-polar R groups
what does the tertiary structure of a protein determine?
it’s function
what is the quaternary structure of a protein?
more than one polypeptide chain working together
what is the difference between a hexose and pentose sugar?
hexose sugars have 6 carbon atoms, whereas pentose sugars have 5 carbon atoms
where are inorganic ions found?
in the cytoplasm and in bodily fluids
name properties of water (4)
- dipole
- has a high specific heat capacity
- has a high latent heat of vaporisation
- is cohesive
how does having a high latent heat of vaporisation give water a function?
how does the dipole nature of water give it a function?
- since it is dipole, other charged molecules can dissolve in water, allowing it to be a great solvent
how does the cohesive nature of water give it a function? (2)
- there’s cohesion between the water molecules, enabling effective transport of water in the xylem of a plant
- there is also high surface tension at the water air boundary
