cell cycle

Interphase

Interval between 2 successive M phase

Preparatory phase

Resting phase

95 % cell cycle

G1

Pre S post M

Cell metabolically active no replication

RNA and protein synthesis

Dna 2c

S phase

Post g1 pre g2

Dna replication [4c 2n=46]

Centriole duplication

Histone synthesis

G2

Post S and Pre M

Tubulin and cyclin protein synthesis

G0

Cell no devide inactive

Exit or suspended form of cell cycle

Heart cell , nerve cell permanent cell

Non histone in all phases

Early prophase

Late prophase

End of prophase

Initiation of condensation of chromosome

Detangles

Duplicated centrosome move to opp. Pole

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Chromosome have 2 sister chromatid

NM start disappearing

MT radiate frok centrosome forking aster

Aster 2 spindle = mitotic apparatus

Animal amphastral

Plant anastral mitosis

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No GB , ER nucleolus NM disintegrated

Metaphase

Complete disintegration of NM and condensation kf chromosome

Chromosome lie at equator metaphasic plate

Spindle attached

Best stage for morpho

Anaphase

Contraction of spindle

Spilttion of centromere

Sister chromatid separate

Move to opp pole

No of chromosome double 4n=8

Cytokinesis

Plant cell - cell plate

Deposition of GB vesicles taht release Calicut and pectin forming

Middle lamella ams desolation of this seamless result in 2 daughter cell

And failure of cytokinesis after karyo leads to syncytium

Animal cell furrow

Contracting ring formed at edges [ centripetal]

That invagination the cell leading to cenge to form 2 new cell

It differ in noth cause of presence kf inextensible cell wall in plants

Significance of mitosis

Mitosis result in 2n daughter cells

Growth of multicellular

Restore nucleo-cytolasmiv ratio

Cell repair like blood cells gut cells

And in apical and lateral cambium

Meiosis 1

Prophase 1

Leototene

Chromosome compaction continues through out

Visible under light microscope

Zygote

Pairing between maternal and paternal chromosome to form synapsis and this synapsed chromosome arw called bivalent teratd = 2 homologous crhomsoem 4 chromatid

Pachytene

Longer then beofre

Characterised by formation of recombination nodule in sister chromatid of homologous chromosomes

Each bivalent consist of 4 chromatid

At end of pachytene CO is complete but homologous chromosomes still attached At site

Diplotene

At start = dissolution of synaptonemal complex

Separation of chomo but still attached at CO site resulting x shape structure called chiasmata

In oocyte diplotene kast for years

Diakinesis

Last stage

Termination of chiasmata

Spindle fire occur

Chromo fully condensed

NM disappeared

Metaphase 1

Recombined bivalent arrange at equator

2 metaohaseic plate

1 spindle attach to one chromo ans 2 ro bivalent

Anaphase 1

Shortening of spindle

Separation of homo chromo

But no spiltting of centromere

Disjunction of chormo

Constitution of gamete decided

Telophase 1

The nuclear membrane reappear

In many cases the chromosome do undergo some dispersion they do not reach extremely extended state of interphase nucleus

Inter kinesis ir intrameiotic is short lives amd no replication

Meiosis 2 same as mitosis