Mitosis in Onion Root Tip Cells

Interphase

Onion root tip mitosis

•cell grows in size

•cell replicates DNA in preparation for mitosis

•individual chromosomes not clearly discernable

•nucleolus may be visible as dark spot

•nucleus is apparent

Prophase

Onion root tip mitosis

•chromatin in nucleus begins to condense and becomes visible under light microscope

•spindle fibers (microtubules) attach to centromeres of chromosomes

•nuclear envelope starts to break down

ProphaseMetaphase

Metaphase

Onion root tip mitosis

•spindle fibers align chromosomes along center of cell (metaphase plate)

Anaphase

Onion root tip mitosis

•as spindle fibers shorten, paired chromosomes separate and move to opposite sides of cell

Telophase

Onion root tip mitosis

•chromosomes are at opposite sides of cell

•nuclear envelope reforms

•cytokinesis begins, in which a new cell wall will be created along the metaphase plate and two daughter cell will be formed

View of Onion root tip using 400x magnification

Overview of phases of mitotic cell cyclein

terp

hase

inte

rph

ase

pro

ph

ase

meta

ph

ase

an

aph

ase

telo

phase