Plastika ima v industriji pomembno vlogo, zato se njena proizvodnja iz leta v leto povečuje. Pomanjkanje učinkovitih metod za odstranjevanje plastike po uporabi se odraža v čedalje večjem onesnaženju naravnih okolij, kjer zaradi vpliva okoljskih dejavnikov počasi razpada in tako predstavlja glavni vir onesnaženja ekosistemov z mikroplastiko. Organizmi, ki so mikroplastiki izpostavljeni bi lahko imeli povečano tveganje za razvoj bolezenskih stanj. Mikroplastika lahko povzroča fizične poškodbe tkiv prebavne in dihalne poti. Služi lahko tudi kot vektor za prenos ostalih toksičnih onesnažil, ki se iz okolja akumulirajo na njeni površini. Pogosto mikroplastika vsebuje tudi nevarne aditive, ki so ji dodani ob izdelavi. Z analizami proteoma lahko identificiramo tarče toksičnega delovanja na molekularni ravni, vendar pa je takšnih raziskav na področju posledic izpostavljenosti mikroplastiki do danes še zelo malo. V raziskovalni nalogi smo proučevali vpliv mikroplastike na proteom modelne praživali Tetrahymena thermophila. Za ločevanje in identifikacijo proteinov, katerih raven se je ob izpostavitvi glede na kontrolno skupino spremenila, smo uporabili tehniko dvo-dimenzionalne poliakrilamid gelske elektroforeze (2-D PAGE), ki smo jo združili z masno spektrometrijo. Identificirali smo 4 proteine, katerih vsebnost je bila pri izpostavljenih kulturah signifikantno spremenjena glede na kontrolno skupino in ugotovili, da lahko preko slednjih mikroplastika vpliva na številne metabolne procese, kot so transkripcija, regulacija celičnega cikla, segregacija kromosomov, translacija, popravne mehanizme DNA, proces apoptoze in razgradnjo proteinov pri testnem organizmu Tetrahymena thermophila. Plastics represents an important material in modern world and its production is growing every year. The lack of efficient methods for its disposal after is resulting in increasing contamination of the environment where it is subjected to slow degradation under constant changes of the environmental factors. This process results in the production of the most microplastics found in the environment. Organisms that are subjected to microplastic particles may have increased risk for developing health problems, caused by physical damaging of the digestive or respiratory tract tissues. In addition, other toxic chemicals that are present in the environment can accumulate on the surface of the particles which can serve as a vector for their transmission. Microplastics also often contains dangerous additives that are added during the production. Proteome analysis is an important tool for identification of the molecular targets of pollutants. However, very few studies have so far been published on the effects of microplastics at the molecular, especially proteome level. In this research two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), coupled with mass spectrometry was used to identify the effects of microplastics exposure on Tetrahymena thermophila proteome. Four differentially expressed proteins were identified after exposing the model organism Tetrahymena thermophila to polyethylen beads. The results revealed that microplastics can affect different metabolic pathways such as transcription, cell cycle regulation, chromosomal segregation, translation, DNA repair mechanisms, apoptosis and protein degradation.