Topic 30: Amino acids, proteins and DNA Flashcards
Amino acid
a carboxylic acid group (-COOH) and an amine group (-NH₂) usually around a chiral carbon
Naming amino acid
2-aminoethanoic acid
anoic acid plus whatever groups
Zwitterion
A molecule containing both a positively charged group (cation) and a negatively charged group (anion)
Can come from amino acids. Isoelectric point
Amino acid with no optical isomerism
Glycine - hasn’t got a chiral carbon centre
Boiling points of zwitterons
Higher than their amino acids as have more imfs
Amino acids acids and bases
Act as both as have both functional groups
Amino acids acid and base reactions
Form salts
Chromatography of amino acids developing agent
Ninhydrin makes the spots of aas more visible
Peptides
Amino acids joining together via an amide or peptide links
Hydrolysis of peptides
Attack takes place at slightly positive C of C=O
The C-N bond broken
Broken into their amino acids
Hydrolysis of peptides water
Very slow
Hydrolysis of peptides acid/alkaline conditions
Quick, produces salts
Acid- amine group protonated
Alkaline - acid group becomes sodium salts
Mechanism of peptide synthesis
Addition- elimination
Proteins IMFs
Hydrogen bonding
C=O and N-H bonds are polar so H bonding between chains
DNA structure elements
Deoxyribose sugar, Phosphate and Nitrogenous organic base
Nucleotide
Monomers of DNA
Making nucleotide
Two condensation reactions joining the 3 parts together making water
Bond between nucleotides
Phosphodiester, covant bond between phosphate group and pentose sugar on neighbouring nucleotide
Why are DNA bases bases?
They accept a proton
Why is DNA acidic
Can donate a proton from phosphate
IMFs between DNA bases
H bonding
3 between C and G
2 between A and T
DNA replication
Basic expaination
H bonds break
Free nucleotides pair
Recoils
2 New strands
Cisplatin
Anti-cancer drug
cis-[Pt(NH3)2Cl2]
Cisplatin shape
Square planar
How cisplatin works
Lone pairs on nitrogen on G dative bond with Pt
water displaces Cls on Pt
Water ligands displaces in ligand substitution by N on G
Distorts the shape of DNA preventing replication
Cisplatin side affects
Works on normal DNA but mostly on cancer as faster, hair follicles have fast DNA replication so hair falls out
Primary structure of protein
Amino acid sequence
Secondary structure of protein
H bonding
Alpha helix/ beta pleated sheet
Bonding in proteins
Hydrogen
Ionic between different groups
Disulphide bridge (sulfur-sulfur bond
Tertiary structure of protein
3D shape
Mixture of different bonds
Determining protein structure
Reflux in conc. HCl to break into its amino acids
How enzymes work
Lock and key
Substrate must fit and be at right orientation to react.
Also temp. have IMFs between
E- move within substrate lowering activation energy
Stereospecificity of enzymes
Will only catalyse the reaction for one of the other enantiomer of a molecule.
Enzyme competitive inhibition
Similar structure to substrate
Competes with substrate for active site
Stops harmful enzyme catalysed reactions in the body
