Amino Acids, Proteins & DNA Flashcards
What is a zwitterion
An amino acid in neutral conditions
- has a COO- group and a NH3+ group
Why do zwitterions have a higher melting point than amino acids that are not charged
Because of the ionic interaction between zwitterions compared to the weaker H bonding that occurs in the no charge form
Describe a basic vs an acidic amino acid
Basic - have an extra amine group
Acidic - have an extra carboxylic acid group
What happens to amino acids structure in acidic conditions/low pH
All amine groups change to NH3+
What happens to amino acids structure in alkaline conditions/high pH
All carboxyl groups change to COO-
How could you determine protein structure from a diagram?
Does the chain show bending and folding?. If no - 1°
Does it show bonding between R groups? No- 2°, yes - 3°
Describe how secondary protein structure forms
- nitrogen and oxygen are very electronegative
- Therefore C=O and N-H are polar
- Which results in the formation of a hydrogen bond between O and H
- The loan pair on the oxygen atom is strongly attracted to the Delta positive H
Why can a stereospecific active site only bond to one enantiomeric form of a substrate or a drug
If the substrate is chiral then it is likely that only one enantiomer will have the correct stereochemistry to fit in the active site of the enzyme. So only one isomer will be catalysed
How do scientists design enzyme inhibitors
With computers
How would you identify the DNA base in the question
- if it has 2 rings and O2 then it’s guanine, if it has no O2 then it’s adenine
- if it has 1 ring and CH3 then it’s thymine. If it has no CH3 then it’s cytosine
How do DNA bases react with sugar phosphate
The N-H group on the base reacts with the OH on the sugar
Why does cisplatin prevent DNA replication and treat cancer
It bonds to the DNA in cancer cells and creates a distortion in the strand so it can’t unwind and be copied
What kind of bonds are disulfide bridges
Covalent bonds
