  Cellular tissue behavior is a multiscale problem. At the cell level, out of
equilibrium, biochemical reactions drive physical cell-cell interactions in a
typical active matter process. Cell modeling computer simulations are a robust
tool to explore the countless possibilities and test hypotheses. Here, we
introduce a two dimensional, extended active matter model for biological cells.
A ring of interconnected self-propelled particles represents the cell.
Translational modes, rotational modes, and mixtures of these appear as
collective states. Using analytic results derived from active Brownian
particles, we identify effective characteristic time scales for ballistic and
diffusive movements. Finite-size scale investigation shows that the ring
diffusion increases linearly with its size when in collective movement. A study
on the ring shape reveals that all collective states are present even when
bending forces are weak. In that case, when in translational mode, the
collective velocity aligns with the largest ring's direction in a spontaneous
polarization emergence.
