Chromosomic number remains constant
→
Takes pla ce in every part of the organis m except in germ cells
→
Asexual divis ion
→
Cell is at the end of G2
a.
Chromatin condenses into chromosomes (vis ible)
b.
Nuclear envelope and the nucleolus disappears
c.
Centrosome dupli cates and situates at each pole of the cell
d.
Centrosomes begin to produce chromosomi c microtubules that attach to the centromere
each chromosome. Each centromere has attached 2 (one from each centrosome)
e.
Centrosomes produce continuous microtubules, that connect both centrosomes
f.
Achromatic/Mi totic Spindle is set
g.
Prophase
1.
Chromosomes condenses to their higher level
a.
Spindle is completely formatted
b.
Microtubul es move the chromosomes to the equatorial plate and are lined there
c.
Metaphase
2.
Chromosomic microtubules shortened and the centromere breaks, separating both sister
chromatids (anaphas ic chromos omes)
a.
New microtubules are created between sister chromatids -> Interzonal fibres
b.
Anaphasic chromosomes grouped in the pole of the cell (46 at each pole)
c.
Anaphase
3.
2 nuclear envelopes appeared
a.
Chromosomes become chromatin in each of the nucleus
b.
2 nucleolus are formed
c.
Spindle dis appears
d.
Telophase
4.
Cytoplas m divis ion to form 2 cells
a.
THERE COULD BE MITOSIS WITHOUT CITOKYNESIS (e.g Myocytes)
b.
Membrane vesicl es full of cellul ose li ne in the centre and fuse together to form 2
membranes, and the cellul ose released form the cell wall.
i.
Plants Cytokinesi s
c.
Actine (protein) lines in the centre and extrangul ates the cell until it divides in 2
(cleava ge furrow)
i.
Animal Cytokinesis
d.
Cytokinesis
5.
MITOSIS
MEIOSIS
MITOSIS
martes, 24 de enero de 2017
16:33
CELL DIVISION página 1
