Amino Acids and DNA A2 Flashcards
What’s the functional group of amino acids
Carboxylic acid and primary amine
What are zwitterions
Ions that have a permanent positive and negative charge, but is overall neutral
What occurs when amino acids are placed with something highly acidic
The lone pair at the amine accepts a H+ ion, forming a positive ions
What occurs when amino acids are placed with something highly alkaline
The -OH loses a proton to form a negative ion
What occurs when two amino acids react
Forms an amide linkage -CONH-. This is a peptide
What are proteins
Molecules containing more than 50 amino acids, forming a polypeptide
What is the primary structure of a protein
A fixed sequence of amino acids for each particular protein
What occurs when polypeptides are boiled with HCl calatyst
All the original amino acids are reformed as the bonds are hydrolysed
What is the secondary structure of a protein
Forms either a helix or a pleated sheet structure, held together by hydrogen bonds or sulfur-sulfur bonds
Where do sulfur-sulfur bonds come from
Amino acids like cysteine has sulfur side chain which can bond the sulfurs together
What is the tertiary structure of a protein
The alpha-helix or beta-pleating sheet can itself be folded into 3 dimensions, containing hydrogen bonds, sulfur-sulfur bonds and ionic interactions
How can the structure of a protein be identified
Reflux with 6 moldm-3 HCl to hydrolyse the protein into amino acids, forming a mixture. This is then used on thin-layer chromatography
Describe thin-layer chromatography
Mixture of amino acids are placed on a starting line and a solvent is placed 0.5cm below the starting line. After some time, the solvent will go up pulling each amino acids at different rates, depending on the affinity for their stationary phase
What is done to the amino acids at the end of thin-layer chromatography
Developing agents are sprayed on the plate such as ninhydrin (or UV) to form a purple compound. The amino acids will be separated
How to calculate Rf
Distance moved by spot / Distance moved by solvent
What are enzymes
Protein-based catalysts, optimised for just one reaction
Describe the shape of an enzyme
They have a crevice called the active site, where the catalysis takes place
What does stereospecificity mean
The active site of an enzyme is so specific that it can catalyst only one of a pair of enantiomers
How to stop an enzyme’s power to catalyse
Enzyme inhibition where a molecule similar to the shape of the substrate is produced, taking its spot. Penicillin does this
How are drugs produced to cause enzyme inhibition
Using computers to analyse long protein chains
What are nucleotides
Monomers which make up the DNA
What makes up a nucleotide
Phosphate group, bonded with the sugar 2-deoxyribose and one of the four organic bases
Describe the full structure of DNA
DNA exists as two complementary strands arranged in the form of a double helix, via hydrogen bonds
What is the example of an anti-cancer drug
Cisplatin, with the formula Pt(Cl)2(NH3)2
How does cisplatin work
They bond to strands of DNA, distorts their shape and stop replication of cells. A dative bond is formed between platinum and a nitrogen atom on guanine
What are the issues with cisplatin
They can stop the replication of healthy cells like hair cells
