Bacterial Growth and Division
527
D-period
The time between termination of DNA replication and cell division. In
Escherichia coli
,
the D-period, for cells growing between 20 and 60 min doubling times, is a constant of
approximately 20 min.
Multiple Forks
The situation that occurs when initiation of DNA replication occurs on a molecule that
has not Fnished its previous round of replication; there are forks upon forked material.
Cytoplasm
The collective name for the numerous components of the cell that are not associated
with either the cell wall or the genome. It is composed of the small molecules such as
ions, metabolites, and cofactors, macromolecules such as soluble enzymes, tRNAs,
mRNAs, and higher complexes such as ribosomes.
Peptidoglycan
The stress-bearing, presumably shape-maintaining, layer of the bacterial cell wall. It is
composed of glycan chains cross-linked with amino acids.
Cell Membrane
The lipid-containing structures that lie adjacent to the peptidoglycan layer. Some cells
have a single membrane layer, while others have two different membranes, an outer
and an inner membrane.
Segregation
The distribution of cell material from the dividing mother cell into the two daughter
cells. Different cell components may have different segregation patterns.
Origin
A sequence on a chromosome or a plasmid where normal replication of DNA initiates.
Terminus
A point or region on a chromosome or plasmid where a round of replication
terminates.
Bidirectional Replication
Replication of DNA with two replication forks proceeding in opposite directions away
from the origin of replication.
GC-skew
The excess (or deFcit) of G residues over C residues within a single strand of DNA.
While G
=
C in a double helix, an individual strand may have an excess of G within a
region or an excess of C residues within a region.
FtsZ Ring
The ring of synthesis of the pole region during pole formation.
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