Biomaterials (Lichtenegger) - Exam Questions 2016

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Joshy
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Registriert: 05.10.2010, 14:01

Biomaterials (Lichtenegger) - Exam Questions 2016

Beitrag von Joshy »

Attached you find today's exam of Biomaterials (24.5.2016).
Du hast keine ausreichende Berechtigung, um die Dateianhänge dieses Beitrags anzusehen.

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_Hofi_
Beiträge: 24
Registriert: 29.01.2015, 19:04

Re: Biomaterials (Lichtenegger) - Exam Questions 2016

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Danke vielmals!

shevegen
Beiträge: 8
Registriert: 02.02.2012, 13:14

Re: Biomaterials (Lichtenegger) - Exam Questions 2016

Beitrag von shevegen »

24.05.2016:

Das ist ein Scan - ich habe mir erlaubt das ganze abzutippen; ich glaube das ist für andere einfacher, da sie dann einfach copy/pasten können. :)

1) Structual Levels of Proteins (4 Credit Points, CP):
a) What is the primary, secondary, tertiary and quarternary structure of a protein?
b) What does it depend on which secondary structure is realized? What is a Ramachandran plot?
2) Keratin (4 CP):
a) Briefly describe the structure of Keratin at the molecular level!
b) How does the presence of the amino acid cysteine influence the mechanical stability of keratin?
c) What is the difference between hair keratin and feather keratin?
3) Remodelling of bone (4 CP):
a) Describe the remodeling process in bone! Which cells are involved and what are their functions?
b) What is osteoporosis?
4) Insect Cuticle (4 CP):
c) Chemical composition (main component) of insect cuticle and their arrangement in the composite.
d) Insect Cuticle can be soft or stiff at very similar density. Name and briefly describe at least 2 strategies in insect cuticle to tune the mechanical properties! What is "tanning"?
5) Reaction Wood / diagram reading exercise (4 CP)
a) The mechanical properties of wood strongly depend on the orientation of cellulose fibrils in the wood cell wall (microfibril angle; MFA). Below you find stress-strain curves of wood with different MFA (20° and 50°). Mark the correct ones!
b) Wood adapts to repeated, excessive loading by forming reaction wood. The below stems of trees are subject to constant wind forces (direction of wind marked by arrows) and contain tension and compression wood respectively (thickening of stem).

-> Which one is tension and compression wood? Mark them correctly in the diagram.
-> In which tree species do you find one or the other? Mark the check box. (Available are: conifer and deciduous tree; conifer is softwood, deciduous tree is hardwood)
c) Below the cellulose microfibril arrangement in tension and compression wood is shown (longitudinal cell axis denoted by dashed line)

-> Which one is tension and which one is compression wood? Mark them correctly in the diagram.
-> Why is the arrangement different? Describe the functionality of tension wood and compression wood.
6) Self-assembly (4 CP)
Self-assembly is driven by physical forces, typically weak ones.
a) Name at least two relevant forces!
b) The thermal energy at room temperature is about 25 meV (milli electron Volt). Which is the (approximate) binding energy of the above weak forces?
c) Describe an example of self-assembly in a biological tissue involving one of the above forces (2-3 sentences)

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Also 24 Punkte in Summe, 6 Fragen zu je 4 Punkte.

Edit: Tanning bedeutet so viel wie "to chemically harden a substance". Also
meistens im Kontext zur Insekten-Haut bzw. eben zum Insekten-Panzer.

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