Page 6 - Meiosis_FULL

L

M I

Before meiosis begins, the cell nucleus
copies its genetic material
using a process called
DNA replication. DNA

new DNA Prophase I (chromatin)
strands replicated

nuclear
Prophase I membrane

Meiosis starts when the nuclear membrane
breaks down, chromatin condenses and the
replicated chromosomes become visible.

Prophase I chromosome
Synapsis parent cell

Prophase I
Synapsis

Prophase I - S

Homologous chromosomes
move together to form
pairs. This is referred to
as synapsis. An exchange
of DNA segments called homologous
crossing-over often occurs chromosome pairs
during synapsis.
cross-over occurs crossing-over chromatids
occurs
crossing-over Metaphase I
occurs chromatids
spindle
bers
Prophase I Metaphase I
Synapsis
The homologous pairs of
chromosomes line up in the
center of the cell. Spindle fibers
attach to each chromosome at
the centromere. chromatids
centromere
crossing-over
occurs
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