The Cell - Challenges in Delivery of Therapeutic Genomics and Proteomics - page 31

Maternal homologue
Paternal homologue
DNA replication
Pairing of homologous chromosomes
Crossing over
Cell division I
Cell division II
Figure 1.14 Cell division by meiosis.
the homologues separate with their individual sister chromatids joined together and
move to opposite poles to generate two cells. Each cell so formed has one of the
homologues. These cells from meiosis I proceed to meiosis II, which is similar to
mitosis. The two sister chromatids of the homologues now separate to ultimately
generate four haploid cells ( Fig. 1.1 ) [-10] .
1.8.4 Cell Death—Apoptosis
Multicellular organisms are organized communities of specialized cells in which the
number of cells are under strict control. This efficient regulation is achieved by exer-
ting control over the cell cycle as well as by programming cell death. The process by
which the cell activates its death program to bring an end to unneeded cells is called
apoptosis, or programmed cell death.
Cells that have undergone some sort of injury tend to swell and burst, spreading
their intracellular material in the nearby region. This mode of cell death is called