SCI260–IntroductiontoBiochemistryLesson6

1. Describe(inwords)theoverallstructureofalipidbilayer.

2. Whataretheproperties(i.e.,characteristics)ofthelipidbilayerofacellthatmakeitimpermeabletoionsandmostmolecules?

3. Describetheroleofcholesterolinmaintainingthefluidityofthelipidbilayerofa

cell?

4. Thetriglyceridesinanimalstendtobesolids(i.e.,fats)atroomtemperaturewhereasthetriglyceridesinplantstendtobeliquids(i.e.,oils)atroomtemperature.Basedonthisfact,whatcanyouconcludeaboutthecharacteristicsofthefattyacidsinanimaltriglyceridescomparedtothefattyacidsinplanttriglycerides?

5. Peanutoilcontainsahighpercentageofmonounsaturatedtriglycerideswhereas

vegetableoilcontainsahigherpercentageofpolyunsaturatedtriacylglycerols.Abottleofpeanutoilandabottleofvegetableoilarestoredinapantrywithanoutsidewall.Duringacoldspell,thepeanutoilfreezes,butthevegetableoilremainsliquid.Explainwhy.

6. HowmanymoleculesofATParegeneratedwhenstearicacid(i.e.,stearate),an

18-carbonsaturatedfattyacid,iscompletelyoxidizedviathebeta-oxidationpathwayinthemitochondria?a) 112b) 129c) 146d) 163

7. Whichofthefollowingfattyacidsbelowareessentialforhumans?*Selectoneor

more.a) Oleicacidb) Linoleicacidc) Linolenicacidd) Palmitoleicacide) Eicosapentaenoicacid(EPA)

8. RefertoQuestion7,lookupthestructuresofeachfattyacidthatisessentialandexplainwhytheyareessentialforhumans?

9. Aretransfattyacidssaturatedorunsaturated?

10. Providefour(4)examplesoffoodsthatcontaintransfattyacids.Youmayuseyourtextbookand/ortheinternettoassistyou.Youwillearn10pointsforcorrectlyansweringeachquestion(maximumpointsearned=100points).