Meiosis Notes
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Introduction
______________ reproduction requires meiosis.
_____________ is a process in which a _________ cell divides to produce cells with _____ the
genetic material of the parent.
NOTE (This is not on the website. This is extra information provided by the teacher): Haploid
cells contain only half of the number of chromosomes needed to make an organism. The most
common type of haploid cell is a gamete or sex cell (sperm or egg). A diploid cell has a whole
set of chromosomes. A diploid cell is created when a sperm fertilizes an egg creating a zygote
(diploid cell). In humans, a diploid cell (zygote) contains 46 chromosomes. If a haploid cell
contains only half the number of chromosomes, how many will it have? ______
A diploid _________ cell divides to make _____ haploid cells.
In sexual reproduction, ___________ gametes from two individuals then combine to produce a
diploid ____________.
Offspring resulting from _________ reproduction is genetically ____________ from both
parents.
Interphase
DNA ______________ takes place during interphase.
Chromosomes are not __________ during this phase.
_____________ consists of two cell divisions – meiosis I and ___.
Prophase I
___________ condenses into discrete chromosomes.
Two centrosomes form the __________ spindle and migrate to opposites poles.
The diploid cell contains _______________ chromosomes which pair up later.
One set of chromosomes is ___________ (female) derived while the other is _________ (male)
derived.
The pairing of maternal and paternal chromosomes is called ____________.
During this phase, the _________ envelope breaks down.
Late in prophase I, the _____________ chromosomes exchange genetic material, as indicated
by __________________.
The chromosomes cross over at points called ________________.
______________ chromosomes consist of both maternally and paternally-derived _____.
________________ attach to the chromosomes, directing them to the _________ plate.
Draw a representation of crossing over:
Metaphase I
_____________ chromosomes have lined up on the ______________ plate in a pair-wise
fashion, with one ____________ on either side of the plate.
Note that the chromosomes assort _______________. For example, the maternal
chromosomes align randomly, not necessarily on the same side of the plate.
Anaphase I
Chromosomes from each pair move to _________ poles of the cell.
The ___________ of the chromosomes do not divide, so each chromosomes still consists of two
sister ____________, which now may not be genetically identical due to ________________.
Telophase I
Chromosomes ___________, nuclear membranes _________, and the _________ divides in a
process called _______________.
A short interphase period occurs called ___________. Note that DNA replication does not occur
during this period.
Prophase II
______________ again condenses into discrete chromosomes.
There are now only a _________ number of chromosomes per cell.
Each chromosome consists of two _________ joined together by a _____________.
Metaphase II
Chromosomes have lined up at the ___________ plate.
___________________ from opposite poles attach to each sister ___________ of a
chromosome.
Anaphase II
The centromeres ___________, and both chromatids become ______________ chromosomes
and move to the opposite poles of the cell.
Telophase II
Chromosomes again ____________ and nuclear ___________ reform.
Depending on the species, _______________ may occur.
Conclusion
Meiosis and sexual reproduction produce genetic ____________.
When a ________ cell divides by meiosis to produce gametes, each of the four daughter cells is
genetically _________.
The uniqueness arises in part from the _____________ assortment of chromosomes in meiosis.
Through independent assortment each ____________ cell randomly receives either a
_________ derived homolog or the ____________ derived homolog from each chromosome
pair.
In addition, the process of ___________ over produces chromosomes that have unique
combinations of paternally and maternally derived regions.
This shuffling of the __________ material produces genetically unique __________, each of
which can fuse with another unique gamete during _____________ to produce a unique
_______________ of the next generation.