Amino Acids, Proteins And DNA Flashcards
What is the structure of an amino acid?
Contains both an amine and carboxyl group
NH2RCHCOOH
What are zwitter ions?
Amino acids exist as zwitter ions
Where the amine group has accepted an extra hydrogen to become positively charged and the carboxyl group has donate a hydrogen to become negatively charged
Gives amino acids it’s amphoteric properties
What are the amphoteric properties of amino acids?
The amine group is able to accept hydrogen atoms and therefore act as a base
The carboxyl group can donate hydrogen atoms and act as an acid
What reactions can take place with the acid end of an amino acid?
React with:
Metal oxides to form a salt and water
Alkalis to form a slay and water
Carbonates to form a salt CO2 and water
Alcohols to form an Ester and water
What reactions can take place with the amine end of an amino acid?
The lone pair of electrons in the nitrogen can accept a hydrogen atom and form an ammonium salt.
How are proteins formed?
Via a condensation reaction between the carboxyl is acid end of one amino acid and the amine group of another amino acid
Forms a peptide bond
Proteins are polypeptides (50+ amino acids)
How can proteins be hydrolysed?
By heating with conc HCL
How can individual amino acids be separated?
Using thin layer chromatography
Use ninhydrin to make them visible
What is the primary structure of a protein?
Sequence of amino acids in the polypeptide chain
What is the secondary structure of a protein?
How the amino acid forms an alpha helix or beta pleated sheet due to hydrogen bonding.
This can easily be disrupted by temperature or pH
What is the tertiary structure of a protein?
The 3D shape the alpha helix or beta pleated sheet is folded into.
This is held together by hydrogen bonds, ionic bonds or disulphide bridges between the R groups of the amino acids.
Are amino acids chiral molecules?
Yes all except from glycine which has the R group of H
What are enzymes?
Biological catalysts which increase the rate of metabolic reactions
What are the structures of enzymes?
Usually globular tertiary proteins
Catalytic activity at the active site
Substrates fit into the active site and bind temporarily via intermolecular forces
This bonding promotes the movement of electrons within the substrate lowering the activation energy for the reaction
Why are enzymes said to have stereospecificity?
Only the complementary shape substrate will fit into the active site as the bonds have to be in exactly the right place.
Even the wrong stereoisomers (enantiomer) will not be catalysed by the enzyme.