if I put zeros at the end of an input sequence, and take fft, then take ifft of a greater length by appending zeros to the fft output, will the zeros of the input sequence reflect on the final ifft output?

if I put zeros at the end of an input sequence, and take fft, then take ifft of a reater length by padding zeros to the fft output, will the zeros of the input sequence reflect on the final ifft output?
I tried to do this in MATLAB, it seems the last part of the final IFFT output deviates from being nearly zero in the absence of any zero-head in original data.
But, when I add zero at the beginning of the data as well, the last part of the data seems nearly being zero.
Could anyone give any mathematical explanation to this?