BIOL 1500 Chapter Notes - Chapter 9: Microfilament, Spindle Apparatus, Centromere

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Published on 16 Apr 2013
Jasmine Nathaniel
Chapter 9
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The Cycle of Cell Growth and Division: An Overview
The Products of Mitosis Are Genetic Duplicates of the Dividing Cell
o Three elegantly interrelated systems
o One component is an elaborate master program of molecular checks and balances that
ensures an orderly and timely progression through the cell cycle
o Process of DNA synthesis replicates each DNA chromosome into two copies
o Final system is a structural and mechanical web of interwoven cables and motors of the
mitotic cytoskeleton that separates the DNA copies precisely into the daughter cells
o Meiosis produces the daughter nuclei
o Cells that are the products of meiosis may function as gametes in animals and spores in plants
Chromosomes Are the Genetic Units Divided by Mitosis
o In eukaryotes, the hereditary information of the nucleus is distributed among several linear DNA
o These molecules are combined with proteins that stabilize the DNA, assist in packaging DNA
during cell division, and influence the expression of individual genes
o Most eukaryotes have two copies of each type of chromosome (diploid)
o Other eukaryotes have one copy of each type of chromosome (haploid)
o Some have more than two copies (ploidy)
o Replication of the DNA of each individual chromosome creates two identical molecules (sister
o Sister chromatids are held together until mitosis separates them
o Chromosome segregation: equal distribution of daughter chromosomes to each of the two cells
that result from cell division
The Mitotic Cycle
Interphase Extends from the End of One Mitosis to the Beginning of the Next Mitosis
o G1 Phase: initial growth stage
o Cell makes various RNAs, proteins, and other types of cellular molecules but not nuclear
o If cell divides: DNA replication begins, initiating the S phase
o Stage where many cells stop dividing (G0 phase)
o S Phase: cell duplicates chromosomal proteins and DNA and continues synthesis of other cellular
o G2 Phase
o Cell synthesizes RNAs and proteins and cell continues to grow
o At the end of this phase, mitosis begins
After Interphase, Mitosis Proceeds in Five Stages
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