Name:______________________________________________________________ Class: ______ Date: ___________
Meiosis: Reading
Instructions: Read and answer the question pages your teacher provides.
Meiosis and mitosis are different cell divisions
with entirely different goals. During mitosis, the
mother cell’s goal is to create two identical
daughter cells. Each daughter cell needs to have Mitosis
an identical copy of the mother’s genetic
material. Each of the mother’s replicated
chromosomes splits and each daughter cell
receives identical chromosomes.
During meiosis, the mother cell is not
dividing to produce 2 identical daughter
Meiosis Meiosis
cells. The goal of meiosis is to produce 4 I II
nonidentical daughter cells that have half
the number of chromosomes as the mother
cell. Mother cells that undergo meiosis are
diploid, meaning they have pairs of very
similar chromosomes that may have slightly
different genetic material.
In the mother cell in the picture on the right, the mother cell has
4 chromosomes. Two chromosomes are larger and are part of a
homologous pair. Homologous pair chromosomes are not
identical but very similar to each other in length and in what
DNA information they contain. The two smaller chromosomes Homologous
make up another homologous pair. When the mother cell divides pairs
in meiosis I, one chromosomes from each homologous pair will go
to two intermediate cells. These two intermediate cells will then
divide in meiosis II and their replicated chromosomes will divide
to form chromosomes in their four daughter cells. These four
daughter cells are called gametes. Each gamete will have half of
the mother’s chromosomes (1 from each pair) and that gamete is
Prophase I
called haploid.
At the beginning of meiosis I, the mother cell is in interphase. The
cell enters prophase I of meiosis, something very unique and different
happens! Homologous chromosomes pair up! Chromosomes that are
homologous to each other pair up and “stick” together in a process
called synapsis. Sometimes the homologous chromosomes switch
segments with their “sister” chromosomes in a process called crossing
over. During prometaphase I of meiosis, spindle fibers begin to form
and they start moving the pairs to the center of the cell.
© Bethany Lau 2016 1
Name:______________________________________________________________ Class: ______ Date: ___________
Meiosis: Reading continued
In metaphase I, the pairs are all lined up and Metaphase I Anaphase I
connected to spindle fibers coming from each pole
of the cell. At the beginning of anaphase I, the
pairs separate and one chromosome from each
pair starts to travel to each pole of the cell. Notice
that the whole replicated chromosomes (with two
chromatids each) travels to the poles!
During telophase I, the two new cells separate and cytokinesis Prophase II
occurs.
After telophase I and the two intermediate cells form, they do NOT go
through interphase and DNA replication. They go through a short
“resting” phase called interkinesis. Centrosomes replicate, the nucleus
reforms around the chromosomes, and then the cell enters prophase II.
Meiosis II begins. Meiosis II resembles mitosis in many ways.
During prophase II, replicated chromosomes are visible, the nuclear Metaphase II
membrane disappears again, and the centrosomes start moving to
opposite poles. During prometaphase II, spindle fibers begin to form
and they start to move the replicated chromosomes to the center of the
cell.
At metaphase II, replicated chromosomes are lined up in the center of
the cell. At the beginning of anaphase II, the replicated chromosomes
split! The chromatids of the replicated chromosome now become Anaphase II
individual chromosomes and they start to move towards the poles of the
cells.
During telophase II, the cells divide into the four individual daughter
cells called gametes. The nuclear membrane reforms around the
chromosomes.
Meiosis is important because it produces gametes, which
form the eggs and sperm of organisms.
Gametes
Each haploid gamete now has half of the chromosomes
needed for a new organism to grow. When two gametes
(an egg and a sperm) unite, they reform a new single,
diploid cell. That single cell can grow into a brand new
organism, one with a different combination of genetic
material than either of its parent cells.
© Bethany Lau 2016 2
Name:______________________________________________________________ Class: ______ Date: ___________
Meiosis: Questions
Matching: Match each statement with the correct phase.
_____ 1. Chromatin is visible during this phase. A. Interphase
_____ 2. During this phase, chromosomes are first visible. B. Prophase I
_____ 3. Homologous chromosomes “stick” together in a process called synapsis. C. Prometaphase I
_____ 4. During this phase, replicated chromosomes become visible but they do not stick D. Metaphase I
together in pairs.
_____ 5. During this phase, homologous pairs of chromosomes move towards the center E. Anaphase I
of the spindle as the spindle forms.
_____ 6. During this phase, replicated chromosomes move towards the center of the F. Telophase I
spindle as the spindle forms.
_____ 7. At this point in time, homologous pairs of chromosomes are aligned in the G. Interkinesis
center of the cell.
_____ 8. At this point in time, replicated chromosomes (not pairs) are aligned in the H. Prophase II
center of the cell.
_____ 9. Homologous replicated chromosomes in a pair split into separate replicated I. Prometaphase II
chromosomes and begin moving towards the poles during this phase.
_____ 10. Replicated chromosomes split into separate chromosomes and begin moving J. Metaphase II
towards the poles during this phase.
_____ 11. Replicated chromosomes finish moving towards the poles in this phase. K. Anaphase II
_____ 12. Chromosomes (not replicated) finish moving towards the poles in this phase. L. Telophase II
_____ 13. Scientists use this word to refer to a “pause” in between meiosis I and meiosis M. Cytokinesis
II. During this phase, centrosomes replicate but chromosomes do not.
_____ 14. In this event, two cells split into the final four daughter cells. N. Gametes
_____ 15. These are the final products of meiosis.
© Bethany Lau 2016 3
