Vpliv zunanjih sil ter minimizacije proste membranske energije na membrano eritrocita

Ivanuš, Bor (author), Penič, Samo (mentor)

Celiˇcna membrana je izredno zapleten sistem, ki ga je teˇzko analizirati. To ni zgolj zaradi zapletenosti in ˇstevilnih beljakovin, napetosti in sil, ki so v to vpletene, vendar tudi zaradi izredno majhne velikosti celic. Zaradi tega bomo uporabili simuliranje, da napovemo obliko celiˇcnih membran. To obnaˇsanje narekujejo lastnosti lipidov, iz katerih je narejena veˇcina celiˇcnih membran[2]. Analize termiˇcnih fluktuacij smo se lotili numeriˇcno, z uporabo programske opreme trisurf. Pri tem smo upoˇstevali razliko med zunanjim in notranjim pritiskom kot glavni zunanji, ter minimizacijo proste energije na membrani kot glavni notranji vpliv na oblike celiˇcnih membran. Analizirali smo celice brez jeder, saj so na tem podroˇcju najbolj zanimivi eritrociti[13], ki pri ljudeh nimajo jeder. Naredili smo 3 prelete faznega prostora rigidnosti in razlike tlaka. Po vsakem preletu smo doloˇcili pod-podroˇcje, kjer bi prepoznali realistiˇcne in zanimive primere. Po zadnjem preletu smo vse toˇcke (oblike membran) v naˇsem obmoˇcju analizirali glede na njihov reducirani volumen in vezano energijo. Primerjali smo jih tudi z eksperimentalnimi rezultati in priˇsli do zakljuˇcka, da je za veˇcino celic minimizacija proste energije na membrani izredno pomemben proces, ki vpliva na obliko celice in nasprotuje zunanjim silam. To odpove komaj pri celicah z zelo nehomogeno lokalno sestavo membrane, kjer prevladajo deformacije zaradi membranskih beljakovin[8].

• Language: Slovenian
• Keywords: eritrocit, minimizacija proste membranske energije, monte carlo, simulacija, trisurf
• Work type: Bachelor thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2022
• PID: 20.500.12556/RUL-139970
• COBISS.SI-ID: 120934403
• Publication date in RUL: 09.09.2022

IVANUŠ, Bor, 2022, Vpliv zunanjih sil ter minimizacije proste membranske energije na membrano eritrocita [online]. Bachelor’s thesis. [Accessed 11 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=139970

Secondary language

• Language: English
• Title: Analysis of extrinsic forces and membrane free energy minimization on the erythrocyte membrane

Abstract

The cell membrane is an incredibly complex system, which is hard to analyse. This is not only due to its complexity and the many proteins, tensions, and forces to take into account, but also because of the cell’s incredibly small size. As such, simulations will be used to predict the membranes’ shapes. This behaviour is dictated by the properties of the lipids, out of which a majority of the membrane is made[2]. To analyse this phenomenon, we used the trisurf simulation software. In the analysis, we accounted for external forces by inducing a pressure difference within and without the cell. The most important mechanism was the minimization of free energy, which causes the cell to deform into the most energy-efficient shape possible under any pressure. We disregarded the nucleus due to the fact that erythrocytes are the most interesting cell when it comes to abnormal shapes[13], and human erythrocytes have no nucleus. We started by making 3 sweeps of the rigidity-pressure phase space, after which we determined which sub-space we will analyse next, based on our results. After 3 sweeps, we found an area with sufficiently realistic and interesting results. We analysed all of the points (membrane shapes) in this sub-space by their reduced volume and membrane free energy. We also compared them with experimental results and came to the conclusion that for most cells, minimization of free membrane energy is an important process and can alone determine the final cell shape. This is not true for cells whose membranes are significantly non-homogeneous in certain areas, as locally the proteins will win out and affect the shape, making our model insufficient.

• Keywords: erythrocyte, minimization of free cell energy, monte carlo, simulation, trisurf