3.3 and 10.1 Meiosis Flashcards Preview

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Flashcards in 3.3 and 10.1 Meiosis Deck (7)
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In what way is meiosis a reduction division?

Meiosis involved a halving of the chromosome number from 2n to n and is thus a reduction.


Why is meiosis important to sexually reproducing organisms?

-Halving of chromosome number allows a sexual life cycle with fusion of gametes
-allows for genetic diversity
-fertilization doubles the number of chromosomes each time it occurs so meiosis prevents each generation having double the amount of chromosomes.


Are the sister chromatids of one chromosome identical to each other?

Initially, yes, but DNA replication mistakes change that.


Are the two homologous chromosomes identical to each other?

No, they are homologous but not identical and so map the same genes but can have different alleles.


Define bivalents.

In early stages of meiosis, homologous pairs form bivalents. This consists of four sister chromatids and two homologous chromosomes. Bivalents are also called tetrads.


What is the process of forming bivalents called? What occurs then?

It is called synapsis. During this time, crossing over occurs.


When does crossing over occur? What is its effect?

-Crossing over occurs during Meiosis I.
-It yields chromatids with new combinations of alleles.