O2: 30 Amino acids, proteins, and DNA Flashcards
What properties do amino acids have?
Both acidic and basic.
How do you draw a zwitterion?
NH2 -> NH3+
COOH -> COO-
How do you draw an amino acid in acidic conditions?
NH2 -> NH3+
How do you draw an amino acid in alkaline conditions?
COOH -> COO-
What are proteins?
Sequences of amino acids joined by peptide links.
Explain the importance of hydrogen bonding and sulfur-sulfur bonds in proteins.
Hydrogen bonds exist between polar groups, stabilising the secondary and tertiary structures of proteins.
Disulfide bonds link together and stabilise the tertiary structure.
What is the primary structure of proteins?
The sequence of amino acids.
What is the secondary structure of proteins?
Hydrogen bonds form between peptide links, folding the protein into either an a-helix or B-pleated sheet.
What is the tertiary structure of proteins?
More bonds form between groups in the protein.
e.g. hydrogen bonds, disulfide bridges, ionic bonds.
What does hydrolysis of the peptide link of a protein produce?
The constituent amino acids.
How can amino acids be seperated and identified?
By thin-layer chromatography.
How can amino acids be located on a chromatogram?
Using developing agents like ninhydrin or UV light.
How can amino acids be identified on a chromatogram?
By their Rf values.
Draw a peptide bond.
H-N=C-O
What is the formula for Rf values?
Rf value = distance travelled by spot / distance travelled by solvent
What are enzymes?
Proteins.
Explain the ‘lock and key’ model for enzymes.
Enzymes’ active sites are highly specific so the substrate needs to have a complementary shape in order for the reaction to be catalysed.
Explain stereospecificity in enzymes.
Because enzymes’ active sites are so highly specific, only one enantiomer of the substrate will work. Enzymes are proteins so also contain chiral centres.
How can drugs work as enzyme inhibitors?
The drugs have a similar shape to the substrate so they bind to the active site, blocking it from substrate molecules.
How are drugs designed now?
With the help of computers to model enzymes’ active sites and predict how drugs will interact with them.
What is a nucleotide made up from?
A phosphate ion bonded to 2-deoxyribose which is bonded to a base.
What is the structure of a single strand of DNA?
A polymer of nucleotides linked by covalent bonds between the phosphate group of one nucleotide and the 2-deoxyribose of another.
This results in a sugar-phosphate polymer chain with bases attached to the sugars.
What does DNA exist as?
Two complementary strands arranged in the form of a double helix.
What is cisplatin used as?
An anticancer drug.
