BIS 2A Lecture Notes - Lecture 25: Benign Tumor, Cell Plate, Cleavage Furrow
BIS2A Lecture 25: The Cell Cycle and Mitosis
Cell Division
• Cell division: the process by which one cell produces one or new more cells, mechanism
of reproduction for cells
o Usually involves the replication of DNA and other cellular components, and
division into two daughter cells
o Occurs in highly coordinated manner
Asexual Reproduction
• Cell division in bacteria and archaea
o Binary fission: the process by which cells grow, duplicate major components such
as DNA and ribosomes, and divide into two identical daughter cells
▪ Circular chromosome attached to the plasma membrane and origin of
replication near the attachment site
• DNA replication occurs with both replication forks proceeding in
opposite directions
▪ Cell elongates as DNA replicates, and elongating membrane pulls
chromosomes towards opposite ends of the cell
▪ Formation of ring of FtsZ proteins near the middle of the cell that
accumulates other proteins that recruit membrane and cell wall materials
• Formation of septum that divides cells into two daughter cells
o Process of binary fission strictly controlled but mechanisms remain not fully
understood
• Cell cycle: coordinated process and mechanisms of control for cell division
o Interphase: cells perform cellular functions and prepare to divide, cells spend
majority of the cell cycle within interphase
▪ G1 phase: growth and protein synthesis
▪ S phase: DNA replication and formation of sister chromatids attached by
centromeres, duplication of centrosomes
▪ G2 phase: growth and protein synthesis, duplication of organelles,
formation of microtubules for cell division
• Prepares the cell for division
▪ G0 phase: cells not actively dividing
• Can be temporary under certain environmental conditions or
permanent (nerve cells)
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