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Gamete Cell Division
Meiosis
Interphase
Period of growth and
synthesis
(replication/duplication)
of DNA
 Preparing the nucleus
and cytoplasm for
division

Meiosis I
Prophase I
Nuclear membrane
begins to break
down
 Spindle fibers form
 Chromatin (a blob
of) genetic material
condenses making
clear chromosomes

Tetrad
A set of 2
chromosome pairs
 Is a set of 4 individual
chromosomes (has a
centromere) or 4
individual chromatids
(no centromere)

Crossing over
The exchange of
material between a
pair of chromosomes
in a tetrad
Source of variety in
organisms
Non-disjunction

The tetrads of
chromosomes do
not separate
properly
Metaphase I
The centrioles
migrate to the cell
poles
 The spindle fibers
attach to the
centromere of the
chromosomes
 The tetrads line up
across the equator

Anaphase I
The centrioles signal
the spindle fibers to
pull back
 The tetrads of
chromosomes come
apart

Telophase I
The spindle fibers go
away
 The nuclear
membrane
regenerates
 Each new cell has 2
pairs of homologous
(same structure)
chromosomes
*each new cell has a
membrane

Prophase II
Spindle fibers form
 Nuclear membrane
begins to break
down

Metaphase II
The centrioles
migrate to the cell
poles
 The spindle fibers
attach to the
centromere of the
chromosomes
 The homologous
chromosomes line up
across the equator

Anaphase II
The centrioles signal
the spindle fibers to
pull back
 The homologous
chromosomes come
apart

Telophase II & Cytokinesis
The spindle fibers go
away
 The nuclear
membrane
regenerates
 Each new cell has 2
chromosomes
*each new cell has a
membrane
