Anaphase 1
-
The fourth stage of the first meiotic division (meiosis I), during which
maternal and paternal homologous pairs are separated on microtubules.
Anaphase 2
-
The fourth stage of the second meiotic division (meiosis II), during which
either maternal or paternal sister chromatids are separated on
microtubules.
Chiasma
-
The region of physical linkage between maternal and paternal homologous
pairs during genetic reassortment. Marks the location of crossover
between two nonsister chromatids.
Diploid number
-
The total number of
chromosomes present in a
cell.
Gametes
-
Cells with the haploid number of
chromosomes. Gametes are
created out of germ cells. The sperm and eggs involved in sexual
reproduction are gametes.
Genetic Reassortment
-
A process in which DNA packaged as a chromosome is broken and fragments are
exchanged
with another independent chromosome. Occurs during prophase 1 of
meiosis.
Germ cell
-
Cells that lead to the production of gametes. Produced by meiosis.
Haploid number
-
The number of unique
chromosomes or homologous
pairs in a cell. Half the diploid number.
Homologous pair
-
Refers to two similar
chromosomes in a diploid
cell. One chromosome is derived from the father gamete cell and the other
from the mother gamete.
Meiosis
-
A type of cellular reproduction that results in the formation of four
haploid cells from one diploid cell. Contains two cellular divisions
that follow only one round of DNA
replication.
The type of reproduction that
produces germ cells.
Metaphase 1
-
The third stage of the first meiotic division (meiosis I), during which
chromosomes align at the
center of the cell by way of microtubule force.
Metaphase 2
-
The third stage of the second meiotic division (meiosis II), during which
chromosomes align at the
center of the cell by way of microtubule force.
Microtubule
-
One of three protein components of the cytoskeleton. Long, cylindrical
structures approximately 25 nanometers in diameter. Extend from the
centrosome to all parts of
the cell, forming tracks on which organelles can travel within the cell.
Prometaphase 1
-
The second stage of the first meiotic division (meiosis I), during which the
nuclear envelope breaks down, allowing microtubule access to
chromosomes.
Prometaphase 2
-
The second stage of the second meiotic division (meiosis I), during which
microtubules attach to
chromosomes.
Prophase 1
-
The first stage of the first meiotic division (meiosis I), during which
genetic reassortment takes place. Can be very long occupying up to 90% of
the entire duration of meiosis.
Prophase 2
-
The first, brief stage of the second meiotic division (meiosis II), during which
condensed chromosomes are
visible.
Sister chromatid
-
Refers to the copy of a
chromosomes that results from
DNA
replication
and is still closely linked to its
original.
Somatic cell
-
Any plant or animal cell that is not a germ cell. The class of cell formed
during mitosis.
Telophase 1
-
The fifth and final stage of the first meiotic division (meiosis I), during
which chromosomes arrive at
the poles of the cell and begin to recondense.
Telophase 2
-
The fifth and final stage of the second meiotic division (meiosis II), during
which chromosomes arrive at
the poles of the cell, the nuclear envelope begins to reform, and the
chromosomes begin to recondense.
