Structure Of Biomaterials And Functional Groups

Question 1

Basic properties of organic molecules

Answer 1

• carbon compounds
• gases, liquids or low melting point solids
• burn in oxygen to give Co2 and water
• insoluble in water

Question 2

Alkanes, alkenes and alkynes

Answer 2

• only hydrogen and carbon
  Alkanes: CnH2n+2
  Alkenes: CnH2n
  Alkynes: CnH2n-2

Question 3

Conjugated systems

Answer 3

• more than one double bond separated by a single bond (single double single double)
• extra stability
• long systems absorb UV-VIS light - colouring

Question 4

Aromatic systems

Answer 4

• special class of conjugated systems
• flat ring systems with conjugated bonds
• number of pi electrons needs to be even but not a multiple of 4
• example: benzene

Question 5

Functional groups

Answer 5

• part of molecule that has its own distinctive properties and reactivity
• Halides R-X (X=F, Cl, Br, I)
• Alcohols R-OH
• Aldehydes R-CHO
• Carboxylic acids R-COOH
• Amines R-NH2
• Ethers R-O-R
• Ketones R-CO-R
• Amides R-CO-NHR
  R is part of the molecule containing only C and H

Question 6

Bonding in glass ionomer cement

Answer 6

Ionic bonding
- acid-soluble aluminosilicate glass
- aqueous solution of polyacrylic acid in concentration of 40 to 50 percent
Mixing: acid lowers pH and glass starts dissolving
Setting: Ionic bonds between dissolving ions
Binding to teeth; Ionic bonds to Ca in dentine

Question 7

Van der Waals interactions

Answer 7

Van der waals forces: sum of attractive or repulsive forces between molecules other than those due to covalent or ionic bonds, neutral molecules or charged molecules
Special case - waters high boiling point, cohesive energy, and surface tension
Dipole interactions: attractive or repulsive electrostatic interactions between permanent charges
Induction: attractive interaction between a permanent multipole and an induced multipole on another
Dispersion: attractive interaction between any pair of molecules arising from interactions of instantaneous multipoles

Question 8

Pi-Pi stacking

Answer 8

Attractive interactions in between aromatic rings - important in nucleotide base stacking within DNA and RNA molecules, protein folding and protein drug interactions

Question 9

Hydrophobic interactions

Answer 9

• desire for non-polar molecules to aggregate in aqueous solutions in order to separate from water
• Aliphatic (alkane) and aromatic functional groups/ domains normally hydrophobic
• entropic effect
• important in protein folding
  Amphiphilic / amphipathic: compound possessing both hydrophilic and lipophilic properties eg soap, detergent - route for compartmentalisation
• cell membranes built of amphiphiles called phospholipids