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Chapter 15 Blog: The Eukaryotic Cell Cycle, Mitosis, and Meiosis

Page history last edited by Suma Gondi 13 years, 2 months ago

A)  This chapter was all about the eukaryotic cell cycle.  Eukaryotes undergo two types of division, mitosis and meiosis.  Mitosis is used for normal cell division, or the creation of somatic cells.  Meiosis is used for the production of gametes by creating haploid cells.  In human cells, there are two pairs of each chromosome.  These pairs are called homologous chromosomes.  In mitosis, these chromosomes separate individually, while in meiosis, these chromosomes pair up during prophase I to form tetrads.  The stages for both mitosis and meiosis are similar, except for that in meiosis, all the stages are repeated. 


Cells spend most of their time in  interphase.  There are three phases of interphase- G1, S (where DNA is replicated), and G2.  If the cell does not pass certain checkpoints, the cell does not continue to the next stage.  Some checkpoint proteins include cyclins and cyclin-dependant kinases.  Cells that do not divide stay at G0.


In mitosis, a cell divides to form two identical new cells.  The original is called the mother, and the new ones are called daughter cells.  Mitosis can be used for asexual reproduction or to maintain multicellularity.


The phases of cell division are prophase, where chromosomes condense, mitosis, where they line up in the middle of the cell, anaphase, where the chromosomes pull apart, and telophase and cytokinesis, where the cells separate.  In Meiosis I, the chromsomes duplicate, and homologous chromosomes pair up, forming tetrads.  Also in this phase, sections of the chromosomes cross over, increasing genetic diversity. 


Organisms are often diploid-dominant, or they can be haploid-dominant, or show alteration of generations.  Chromsomes are usually very distinct in each organism, with a set number, size, location of centromere, and banding pattern.  There are different chromosomal mutations, such as deletions, duplications, inversions, and translocations.  There can also be changes in chromosome number, such as being polyploidy, aneuploidy, or trisomic or monosomic.  Nondisjunction is when chromosomes do not sort properly during cell division.




1)  Phases of Mitosis: (submitted Feb. 12, 2011)  This is a video from Khan Academy that explains the stages of mitosis very well.  It is a really good refresher, since we didn't go over it in class, and I know I forgot a lot about what happened in the different stages!

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2)  Effect of cyclin-dependent kinase (CDK) inhibition on expression, localization, and activity of maturation promoting factor (MPF) and mitogen activated protein kinase (MAPK) in bovine oocytes.

This PubMed article (submitted Feb 13, 2011) is about an experiment done to see what the effect of the inhibition of CDK would ave on MPF and MAPK.  As we learned in class, CDK is a checkpoint protein that is used to determine whether the cell is ready or not to go on to the next stage of the cell cycle.


3)  Meiosis Tutorial: (submitted Feb 13, 2011) This website has a tutorial on the different phases of meiosis, as well as a test at the end where you can quiz yourself. 




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