  Motivated by recent experiments probing shape, size and dynamics of bacterial
chromosomes in growing cells, we consider a polymer model consisting of a
circular backbone to which side-loops are attached, confined to a cylindrical
cell. Such a model chromosome spontaneously adopts a helical shape, which is
further compacted by molecular crowders to occupy a nucleoid-like subvolume of
the cell. With increasing cell length, the longitudinal size of the chromosome
increases in a non-linear fashion to finally saturate, its morphology gradually
opening up while displaying a changing number of helical turns. For shorter
cells, the chromosome extension varies non-monotonically with cell size, which
we show is associated with a radial to longitudinal spatial reordering of the
crowders. Confinement and crowders constrain chain dynamics leading to
anomalous diffusion. While the scaling exponent for the mean squared
displacement of center of mass grows and saturates with cell length, that of
individual loci displays broad distribution with a sharp maximum.
