Amino acids, proteins and DNA

• What is an amino acid?

  An amino acid is a compound with an amine group and a carboxylic acid group.

  
• Why do amino acids exist as optical isomers?

  The second carbon is often chiral, having four different groups bonded to it.
• What is a zwitterion?

  A zwitterion is a molecule that can react as both an acid and a base.

  
• What happens to amino acids in acidic conditions?

  In acidic conditions, the lone electron pair is more likely to accept a hydrogen atom, producing a positive end.
• What happens to amino acids in basic conditions?

  In basic conditions, the hydrogen atom on the -OH group is more likely to be lost, producing a negative end.
• What is the isoelectric point?

  The isoelectric point is when the overall pH of the molecule is zero.
• How can thin-layer chromatography be used with amino acids?

  Thin-layer chromatography can identify unknown amino acids using UV light to view traces on the silica plate.
• What are proteins made of?

  Proteins are sequences of amino acids joined together by peptide links.
• What are the different structures of proteins?

  • Primary Structure: A single polypeptide chain of amino acids.
  • Secondary Structure: An α-helix or β-pleated sheet held with hydrogen bonds.
  • Tertiary Structure: Chains folded into a 3D coil with hydrogen and disulfide bonding.

  
• What is the role of enzymes?

  Enzymes are proteins that act as biological catalysts.
• What is the significance of the active site in enzymes?

  Active sites are specific to a certain molecule called a substrate that enzymes break down.
• What is DNA?

  DNA (deoxyribonucleic acid) is a condensation polymer formed from a sugar, a phosphate, and a base.

  
• What is a nucleotide?

  A nucleotide consists of one sugar, one phosphate, and one base.

  
• What sugar is present in DNA nucleotides?

  The sugar present in DNA is 2-deoxyribose.

  
• What forms the sugar-phosphate backbone in DNA?

  Sugar-phosphate bonds hold together multiple nucleotides into a polynucleotide strand, forming the sugar-phosphate backbone.

  
• What are the four possible bases in DNA nucleotides?

  • Adenine
  • Cytosine
  • Thymine
  • Guanine

  
• How do bases pair in DNA?

  Bases pair up in specific complementary pairs to form a double helix structure.
• What are the complementary base pairs in DNA?

  Guanine and Cytosine bond with three hydrogen bonds; Thymine and Adenine bond with two hydrogen bonds.

  
• What is cisplatin used for?

  Cisplatin is used as an anticancer drug.
• What is the structure of cisplatin?

  Cisplatin is the cis isomer of a square planar complex of platinum.

  
• Why is only the Z-isomer of cisplatin effective?

  Only the Z-isomer is effective because cells in the natural world are chiral and it fits correctly.
• How does cisplatin prevent cancer from spreading?

  Cisplatin bonds to strands of mutated DNA to prevent it from replicating via ligand replacement with guanine.
• What are the side effects of cisplatin?

  Cisplatin can bond to heated DNA strands causing serious side effects such as hair loss.
• How is cisplatin administered to reduce side effects?

  Cisplatin is administered in small amounts to try and reduce side effects.
• Why is cisplatin still used despite side effects?

  The long-term benefits and effectiveness of cisplatin as an anticancer drug mean it continues to be used.
• Alkenes are unsaturated hydrocarbons that contain at least one carbon-carbon double bond.
• The general formula for an alkene is CnH2n