Past Paper Questions

Question 1

Name 4 types of Biomaterials

Answer 1

pacemaker, skin graft, hip replacement, ocular implant

Question 2

What is a phospholipid?

Answer 2

has a polar head group (phosphate) and a hydrophobic tail. They form a bilayer with the polar head group (hydrophillic) pointing outwards towards the aqueous surrounding.

Question 3

What are the 3 main functions of phospholipids?

Answer 3

Building blocks of biological membranes. Hormones and intracellular membranes. Energy storage.

Question 4

What are the 4 main nanostructrues formed by phospholipids

Answer 4

Bilayer, Micelle, Liposome, Lipid monolayer.

Question 5

Describe two methods for surface tension measurement of a peptide solution

Answer 5

Wilhelmy Plate Method. (suspended ring on surface of water) Du Noüy ring (slowly lifting ring out of the water).

Question 6

Explain the meanings of primary sequence, and secondary, tertiary and quaternary structures of a protein.

Answer 6

Primary sequence is the linear order of amino acids. Secondary is local folded structures. Tertiary is 3D shape of whole molecule. Quanternary refers to the arrangement of peptide chains.

Question 7

Describe the non-covelant forces involved in the stabalisation of proteins.

Answer 7

Hydrogen bonds (alpha and beta), ionic bonds (inside and outside of proteins), Van der Waals force, Hydrophobic interaction (folding of proteins)

Question 8

How can you stabilise a bioengineered antibody.

Answer 8

pH adjustment and buffering. Addition of stabilising. Control temperature.

Question 9

What are the key properties of hydrogels that can be used to spread onto wounds.

Answer 9

Semi-permeable. Strong. anti bacterial properties.Biodegradable

Question 10

Describe two structural features and two physical characteristics of a surfactant.

Answer 10

Structural: Hydrophobic tail, hydrophilic head. Physical: Amphiphilic, leads to interfacial adsorption lowering surface tension and allowing water to spread. - Antimicrobial negative charge bacterial cell membranes get broken down.

Question 11

Describe how cationic surfactants and peptides work to kill pathogenic bacteria.

Answer 11

Disrupt the bacterial cell membrane.

Question 12

Explain why a cationic surfactant may not achieve as high selectivity as a cationic
peptide.

Answer 12

cationic peptides can specifically target bacterial cell components.

Question 13

What factors affect the minimum inhibition concentration.

Answer 13

Ph, Ionic strength, aggregation somehow….

Question 14

Describe a method, and key processes involved, in producing lipid nanoparticles
for the delivery of RNA. Justify the lipid components you use.

Answer 14

Cholesterol: structure builder. DLin-MC3-DMA (cationic surfactant): charge neutralisation. Helper lipid: flexibility. DMG-PEG-2000 (outer surface cover) strong steric stabilisation.

Question 15

Give 5 reasons for development of biomedical materials.

Answer 15

Ageing/diseases/cancers, Birth defect, Accidents, War casualties, Beauty

Question 16

Describe the main four structural features of collagens and how these features affect their mechanical behaviour

Answer 16

Amino acid sequence: -Gly-Pro-Hyp-Gly-X. X is any other amino acid. 3 left-handed helical peptide chains coiled together to give aright handed coiled tropocollagen superhelix with periodicity of 2.86 nm. Hydrogen bonding between the glycine residues and the OH groups of hydroxyproline

Question 17

Describe the mechanical behaviour of self-assembled hydrogels. Outline the main
characteristic features desired for topical wound treatment.

Answer 17

They are viscoelastic. Biocompatibility, permeable to oxygen, strong against friction.

Question 18

Why is neutron reflection good for studying buries interfaces?

Answer 18

Nuetrons are uncharged so highly penetrative. Stable. eg (imaging on plane for damage)

Question 19

Give three main properties of biomaterials

Answer 19

Viscoelastic (mechanical), transparant (optical), biocompatible

Question 20

Draw three types of hydrogen bonds

Answer 20

Acceptor H2O—H-OH donor; HO—H-NH-R; R1-H2N—H-NH-R2

Question 21

write the equation for the reaction between 2 amino acids to form a dipeptide

Answer 21

week 6 long qesutions 2

Question 22

Why is tha charge on a protein pH dependent?

Answer 22

Proteins contain charged amino acids, which can dissociate depending on the pH solution, createing different charges

Question 23

Describe a process for measuring the isoelectric point

Answer 23

Measuring the zeta potential. Isoelectric focussing (IEF). Separates charged molecules, carried out in gel with pH gradient.

Question 24

What secondary structure would peptide GIIIQGK-NH2 prefer to adopt.

Answer 24

Anti parallel B sheet.

Question 25

5 main differences in NR and X-ray reflection

Answer 25

Isotopic variateions make it easier to study structures in more detail by parallel runs. NR has less resolution than X-ray. NR is better at resolving complex interfaces. NR avoids contribution of water from NRW by mixing 8.1vol% D2O with H2O0 scattering density. X-ray is better for electron, NR is better for nuclei.

Question 26

What are the key features of viscoelasticity

Answer 26

time dependent deformation, stress relaxatio, strain and rate dependence

Question 27

Sketch temperature, composition diagram for copper and nickle (nickle has a higher melting point. Write equation for amount of liquid in L+a phase.

Answer 27

(Calp - C_A)/Calp - CL) = L /(alp + L)

Question 28

Sketch temperature, composition diagram for copper and Ag

Question 29

Write down equation for strain of a dashpot and how strain is in the maxwell and voight models

Answer 29

maxwell: et = e_spring + e_dash
voight: et = e_spring = e_dash
sigma = visx de/dt

Question 30

What are the hume rothery rules?

Answer 30

To form a solid solution: substitutional solids. -r difference less than 15% - Same crystal - same valance - same electronegativity. Interstitial solid: solute atoms smaller than sites - same electrognegativity - same valence.

Question 31

name two charactersitic properties of hydrogels

Answer 31

• phase difference between stress and strain. - shear storage and shear loss moduli. G’ = (sigma0/eps0)cosPhi.G’‘=sigma0/eps0)cosPhi

Question 32

write equation for debye length, bjerrum length and ionic strength

Answer 32

I = 0.5sum c z^2. Lambda b = e^2/(4pi eps0 epsr kB T). k-1 = 1/sqrt(8pi lambda b N_A *10^3 I)