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 We already now that all cells must replicate their
DNA prior to cell division. In
mitosis and
binary fission, this assures that each new daughter cell has the
same DNA as the original parent cell. In sexually reproducing
organisms, however, genetically variable cells are produced by a
process of cell division called meiosis. These genetically variable
cells, often referred to as
gametes, ultimately can pair to form a new, genetically variable
offspring.
Learning Objectives
- Understand the different stages of
meiosis.
- Comprehend the evolutionary significance
of meiosis.
Topics covered in this Lesson
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 Cell
division is a pretty useful process. You developed from a
single-celled zygote by repeated cell divisions. Bacterial
populations grow exponentially by repeated cell divisions. Most
of the time, cell division results in the production of
genetically identical cells. This occurs either by mitosis
(eukaryotes) or binary fission (prokaryotes). However, a third
type of cell division, found in eukaryotes, results in
genetically variable cells. This process is called
meiosis. Meiosis helps generate the genetic variation
which is an important feature of sexual reproduction.
Learning Objectives
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Understand the differences and
similarities between mitosis and meiosis.
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Be able to describe how meiosis
generates genetically unique cells.
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Know when
crossing over takes place during meiosis and how this increases
genetic diversity.
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Trace the paths of chromosomes
through meiosis.
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Why is it important for gametes
to contain half the DNA of the parent cell?
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