Amino acids, proteins and DNA Flashcards
What is an amino acid?
A compound with an amine group and a carboxylic acid group within the molecule
What are Zwitterions?
Molecules that can act as both an acid and a base.
In acidic conditions, the lone electron pair is more likely to accept a H+, so an NH3+ is produced on the end. (so it is a base)
In basic conditions, the H on the OH group is likely to be lost, forming H2O as a side product. (so it is an acid)
What is the isoelectric point?
The point at which the Zwitterion forms (when the overall pH is zero)
What are proteins?
Sequences of amino acids joined together by peptide links.
How can peptide links be undone?
Boiling the protein in concentrated HCl for 24 hours (hydrolysis)
What is a primary protein structure?
A single polypeptide chain of amino acids
What is a secondary protein structure?
An α-helix or a β-pleated sheet held with hydrogen bonds
What is a tertiary protein structure?
Chains folded into a 3D coil with hydrogen and disulfide bonding
What is disulfide bonding?
S-S bonds that hold tertiary structures together (disulfide bridge). Keep protein structure stable by losing 2 hydrogen atoms. They are covalent bonds
What are enzymes?
Proteins with a tertiary structure that act as biological catalysts. They contain active sites that are specific to a substrate
What is meant by stereospecific?
Enzymes are stereospecific, they can only break down a single enantiomer and have no effect on the other optical isomer
What is DNA?
A condensation polymer formed from a sugar, a phosphate and a base.
What is a nucleotide?
A monomer, the phosphate group is attached to the C group on the sugar, the base to the other C group…?
What are the 4 bases of DNA?
Adenine
Thymine
Cytosine
Guanine
How are bases bonded in DNA?
Via hydrogen bonding
What are the complimentary base pairs?
A-T ; 2 hydrogen bonds
C-G ; 3 hydrogen bonds
Describe how cisplatin works
Cells are chiral, so only the Z-isomer of the drug is effective and will be in the correct orientation to fit the cells. It has to be able to bond to two adjacent Guanine bases. It bonds to strands of mutated DNA to prevent it from replicating via ligand replacement with Guanine.
Describe how cisplatin causes negative side effects
It can bond to heated DNA strands, causing side effects such as hair loss.
