AA, proteins and DNA Flashcards
functional groups of AA
NH2 and COOH
how many naturally occurring AA are there in the body
20
what type of AA are found in the body
alpha
the NH2 is always on the carbon next to COOH
generic formula for an alpha AA
R
I
H2N - C - COOH
I
Hwhich enantiomer do alpha AA exist as in nature
- enantiomer
is the product from AA being synthesises naturally optically active
no
a racemix is formed as the CN- can attack from above or below the planar C=O
in what form do AA exist as solids
zwitterions
what colour are zwitterions
white solids
zwitterion
ions which have both a permanent positive and negative charge but are neutral overall
zwitterion AA
R
I
H3N+ - C - COO-
I
Hwhat happens to AA in acidic conditions
gains a proton on NH2 group
what happens to AA in alkaline conditions
loses a proton from COOH group
peptide linkage
CONH
what name is given to chains of AA up to 50 AA
polypeptide
what name is given to a chain of AA with more than 50
proteins
conditions needed for hydrolysis to occur
6 mol dm3
HCl
reflux for 24 hours
primary structure
sequence of AA along the protein chain bonded by covalent bonds
secondary structure
shape of the protein chain
how is the secondary structure held together
hydrogen bonding
tertiary shape of a protein
alpha helix or beta pleated sheet is folded into a complex 3D shape
how is the tertiary structure held together
hydrogen bonding
ionic interactions
disulphide bridges
van der waals
what is TLC plate made of
plastic sheet coated with silica
this is the stationary phase
describe the process of TLC
spot the samples onto a pencil line a few cm above the base
place this in a beaker with solvent lower than the pencil line
wait until the solvent front is almost at the top of the plate
remove and analyse
how do you calculate the Rf value
distance moved by that substance divided by the distance moved by the solvent front
what is 2D TLC
uses a square TLC plate
spot the AA in one corner then run TLC in first solvent
flip the plate through 90’ and repeat TLC in a second different solvent
what is an enzyme
protein based catalyst that speed up reactions in the body by factors of up to 10^10
structure of an enzyme
globular protein with a creft/crevice in it, known as an active site
how structure help the function
the reacting molecules fit precisely into the active site and are held at exactly the right orientation to react
enzymes increase the ror
reacting molecules form temporary bonds to the enzyme
this weakens the bonds in the molecules promotes electron movement and lowers Ea
what does the stereospecificity of enzymes mean
active sites are so selective of the shape of substrates that only reactions involving one enantiomer are catalysed
example of a drug that works through enzyme inhibition
penicillin
DNA
deoxyribonucleic acid
what does DNA do
present in all cells and is a blueprint from which all organisms are made
cisplatin
Cl NH3
Pt
Cl NH3
function of cisplatin
bonds to strands of DNA to distort shape and prevent cell replication
bonds to N atoms on 2 adjacent G bases
N atom replaces Cl- ligand
