baha al-amiedie

Growth & binary fission in Bacteria
Dr. Baha, H. AL-Amiedi
Ph.D.Microbiology
Binary fission
The growth and division is increased or the synthesis of all cellular constituents from extra cellular environment - the ultimate results of this Is increased in cell size mass and replication &segeration of bacterial DNA and formation of septum which divide the cell in to two progeny cells, the process is coordinate by bacterial membrane perhaps by means mesosomes.
The replication of bacterial genetic (DNA):
During cell growth the DNA replication by process known semi-conservative replication this take place at replication fork, separate helices of DNA act as templates for the new daughter strands. The initiation of replication fork and subsequent DNA polymerase , each daughter cell receive an original strand plus a newly synthesis strand.
Role of mesosomes in binary fission
cytological electron microscope of bacterial cell wall studies suggest that the mesosomes is involved in cell division regarding
1- the splitting of the chromosome and the
2- initiation of the cytoplasmic membrane and cell wall that forms the two daughter cells


Cell division sequence: there are four stage :
1-cell elongates and DNA is replicated.
2-cell wall &plasma membrane begin to constrict
3- cross-wall forms completely separating the two DNA
Copies
4-cells separate.
Bacterial growth Curve:
the bacterial growth curve when bacteria are inoculated in a suitable growth medium and provided with all appropriate requirements for maximum growth and division the growth of cells divided into four phases :
1-- lag phase ( phase of adaptation ) " increase in cell size. This phase is characterize by each of the following
a. cell size is larger than in any other phase
b. there is an increased synthesis of RNA but not of DNA
c. the cell are not dividing
d. the unit of metabolism per cell is greater than in any other phase of growth curve
2--log phase : following in crease in size , the cells begin to divide & multiply at a geometric rate. lncreased in number of bacteria to the extent that media look turbid to the naked eye
( log phase ) this phase is called accelerated phase or logarithmic