ðɪs ɪz dˈuː tə ðə kˈɑːnstənt ɹᵻmˈuːvəl ʌvðə pɹˈoʊtiːn sˈʌbjuːnˌɪts fɹʌm ðiːz fˈɪləmənts æt wˈʌn ˈɛnd ʌvðə fˈɪləmənt, wˌaɪl pɹˈoʊtiːn sˈʌbjuːnˌɪts ɑːɹ kˈɑːnstəntli ˈædᵻd æt ðɪ ˈʌðɚɹ ˈɛnd.
This is due to the constant removal of the protein subunits from these filaments at one end of the filament, while protein subunits are constantly added at the other end.