Amino acids , DNA and proteins Flashcards
What is an amino acid ?
Is a compound with an amine group and a carboxylic acid group
Why do amino acids react as both acids and bases?
- Due to the two functional groups
- in different conditions
What happens in acidic conditions
(Low ph) the lone pair is ore likely to accept a. Hydrogen atom producing a positive acid end to the molecule
What happens in basic conditions ?
In basic conditions (high pH), the hydrogen atom on the -OH group is more likely to be lost, producing a negative (basic) end to the molecule.
What is zwitterion and when do they form ?
- molecule with both a positive and negative charge
- A zwitterion forms when the overall pH of the molecule is zero, known as the isoelectric point.
What can be used to identify unknown amino acids ?
Thin-layer chromatography can be used to identify unknown amino acids using UV light to view the traces on the silica plate.
What is a protein ?
Sequence of amino acids joined together by peptide links
Describe the structure of proteins
Proteins have complex structures which are held together with hydrogen bonds, van der waals forces and sulfur-sulfur bonds.
Describe a primary structure of a protein
single polypeptide chain of amino acids.
Describe secondary structure
an a-helix or ß-pleated sheet held with hydrogen bonds.
Descibe a tertiary structure
chains folded into a 3D coil with hydrogen and disulfide bonding.
What is disulfide bonding ?
- The sulfur-sulfur bonds that hold together tertiary structures are known as a disulfide bridge.
- They keep the protein structure stable by losing two hydrogen atoms.
What is an enzyme and describe its structure ?
- Enzymes are proteins with a tertiary structure that act as biological catalysts.
- They contain active sites that are specific to a certain molecule that they break down, called a substrate.
Enzymes are stereospecific, what does this mean ?
Enzymes are stereospecific, meaning they can only break down a single enantiomer and will have no effect on the other optical isomer.
What is DNA structure ?
join together to form a nucleotide which consists of one of each molecule.
How do base pairs bond together ?
bases pair up to allow a single strand of DNA to join with another via hydrogen bonding to form a double helix structure of DNA.
How many hydrogen bonds form between Guanine and cytosine ?
3
How many hydrogen bonds form between adenine and thymine
2
What is cisplatin and what is it used for ?
- Cisplatin is used as an anticancer drug.
- It is the cis isomer of a square planar complex of platinum.
How does cisplatin work ?
- Cancer spreads by replicating ‘bad DNA.
- Cisplatin bonds to strands of this mutated DNA to prevent it from replicating via ligand replacement with guanine.
Side effects of cisplatin
Hair loss
How can the side effects be combatted
Use cisplatin in small doses
