Cell Cycle and Cell Division
Meiosis I Meiosis II
Telophase Prophase I Prophase II
Metaphase I Metaphase Il
single cell large organisms No discrete elements refor
C
spindle pole
m Anaphase I Anaphase II
Chromosomes cluster Nucleolus
Cell cycle & Division golgi
Telophase I Telophase II
Nuclear envelope
10.1 Cell Cycle
ER
..
Growth spindle pole
Chromosomes cluster
forming
2 daughter nuclei Meiosis I
cell characteristics Prophase I Leptotene
reproduction 10.2 M Phase cytoplasm division
Cytokinesis
2 daughter ce!s
longer
subdivided
based on
Zygotene
Pachytene
Diplotene
10.3 Significance of Mitosis
more complex than mitosis chromosomal
10.1 Cell Cycle Animal cytokinesis behaviour Diakinesis
furrow plasma membrane -
Centromere
Ce! constituents
synthesises two daughter leptotene
10.4 Meiosis
plasma membrane
cell
divides
Ce! genome Ce!
duplicates deepens joins centre
visible light microscope
I dividing chromosomes
10.5 Significance of Meiosis
ce! division
ce! growth DNA synthesis coordinated 2 cell cytoplasm compaction continues
DNA replication
(cytoplasmic increase) genetic
ce! growth
For
control
correct cell
continuous process Only ce! division cycle,division
Plant cytokinesis
10.1.1 Phases of Cell Cycle Di#erent bcz of ce! wa!
new ce! wa!
human ce!s Yeast duration vary formation ice!-plate (middle lame!a )
90 min
organism to organism
24 hours cell to cell mitochondria
distributed 2 daughter
A plastids ce!s
cell cycle
V
interphase M Phase
↓ ↓
multinucleate [ only karyokinesis]
95% 5%
Interphase
·
syncytium formation
23 hr 1 hr M Phase (Mitosis phase) two adjacent ce!s (e.g., liquid endosperm in coconut).
M Phase Significance of Mitosis
cell division or mitosis most dramatic period Mitosis Mitosis
- equational division
' interphase ( resting phase) Subdivided
starts(karyokinesis) 7 ends (cytokinesis)
reorganisation a! ce! components
diploid daughter ce!s ↓ ↓
haploid ce!
nuclear division cytoplasm division diploid ce!s only
G1 phase (Gap 1)
l parent Csome lower plants,
S phase (Synthesis) equational division chromosomes same
genetica!y same insectsS
Preparation progeny ce!s
v W G2 phase (Gap 2)
Karyokinesis involves 4 stages
ce! growth DNA replication
Prophase cell repair restore nucleo-
G1 phase S or synthesis phase Metaphase Prophase cytoplasmic ratio
do not
↑
↑
interval -"
mitosis DNA synthesis or replication
Anaphase show multicellular
organisms epidermis upper layer Zygotene ⑤
- Mitosis Significance
Telophase cell replace
DNA replication initiation golgi growth
↓ -
-
gut lining bivalent or tetrad
ER chromosomes pairing (synapsis)
metabolica!y active DNA doubles no increase in chromosome nucleolus meristematic tissues blood cells
apical H lateral cambium
continuously grows nuclear envelope
homologous chromosomes
no DNA replication If 2C then 4C If 2n then also 2n Electron micrographs synaptonemal complex
·
All life
initiation of chromosomal condensation
Leads to
compact mitotic chromosomes !]).
I
Meiosis
.
G2 phase replicate DNA In nucleus 2 chromatids with centromere
proteins synthesised
In animal
cells E duplicate centriole In cytoplasm
chromosome untangled
During
chromatin condensation centrosome
move
ce! opposite poles
2 asters with spindle "bres
Pachytene
ce! growth continues gametogenesis in plants and animals
forms
G1 S G2 mitotic apparatus
Male ce! (2n) ↳ Sperm (n)
Fertization
Chromosome 2n 2n 2n
Female ce! (2n) 7
Egg (n) Zygote (2n)
DNA 4C
Metaphase
2C 4C Chromosome half
Diploid Haploid Diploid
spindle "bres
-
Centromere
-
7 one pole ⑪
synaptonemal
complex
Some No ce! division Both meiosis1 4 chromatids( bivalent
adult animals r
chromatid nuclear & Ce! division
chromosomes ) clearly as tetrads recombination nodules
(e.g heart ce!s) kinetochore meiosis 2
inactive stage Disc shapeC -
sister chromatid
·
only once enzyme {recombinase}
no proliferate
1x
cell division DNA replication
injury or cell death replace ce!s S phase
opposite pole
↑
metabolically active Attach identical sister b4 meiosis I
quiescent stage (GO) If needed then cell division spindle "bres chromatids
Some exit G1 phase metaphase plate Diplotene dissolution separation
a! chromosomes at equator
disintegration
complete
nuclear envelope
Cell
·
In animals plants
condensation chromosomes synaptonemal recombined homologous
homologous chromosomes +
mitotic ce! division mitotic ce! division mitotic ce! division
chromosomes morphology easily studied - Germ cell non-sister chromatids
complex chromosomes bivalents
Somatic cell except at crossovers sites
Only But some N Both =2 haploid cells X-shaped
Anaphase Meiosis
Mitosis some vertebrates(oocytes ) diplotene for months/ yrs
haploid ce!s
diploid somatic ce!s eg.male honey bees haploid & diploid ce!s Equational division 46 M 1 Reductional division
46
Centromeres split and chromatids separate 46
-
46 ↳
23 M2 Equational division
Diakinesis
23
Chromatids move to opposite poles 2 diploid ce!s xLd7
23 23 23 23 like mitoti division equal chromosome chiasmata terminalisation
If 2n then 4n
-
- >
nucleolus disappears
4 haploid ce!s nuclear envelope broken
chromosomes separation
Meiosis I Meiosis II
Telophase Prophase I Prophase II
Metaphase I Metaphase Il
single cell large organisms No discrete elements refor
C
spindle pole
m Anaphase I Anaphase II
Chromosomes cluster Nucleolus
Cell cycle & Division golgi
Telophase I Telophase II
Nuclear envelope
10.1 Cell Cycle
ER
..
Growth spindle pole
Chromosomes cluster
forming
2 daughter nuclei Meiosis I
cell characteristics Prophase I Leptotene
reproduction 10.2 M Phase cytoplasm division
Cytokinesis
2 daughter ce!s
longer
subdivided
based on
Zygotene
Pachytene
Diplotene
10.3 Significance of Mitosis
more complex than mitosis chromosomal
10.1 Cell Cycle Animal cytokinesis behaviour Diakinesis
furrow plasma membrane -
Centromere
Ce! constituents
synthesises two daughter leptotene
10.4 Meiosis
plasma membrane
cell
divides
Ce! genome Ce!
duplicates deepens joins centre
visible light microscope
I dividing chromosomes
10.5 Significance of Meiosis
ce! division
ce! growth DNA synthesis coordinated 2 cell cytoplasm compaction continues
DNA replication
(cytoplasmic increase) genetic
ce! growth
For
control
correct cell
continuous process Only ce! division cycle,division
Plant cytokinesis
10.1.1 Phases of Cell Cycle Di#erent bcz of ce! wa!
new ce! wa!
human ce!s Yeast duration vary formation ice!-plate (middle lame!a )
90 min
organism to organism
24 hours cell to cell mitochondria
distributed 2 daughter
A plastids ce!s
cell cycle
V
interphase M Phase
↓ ↓
multinucleate [ only karyokinesis]
95% 5%
Interphase
·
syncytium formation
23 hr 1 hr M Phase (Mitosis phase) two adjacent ce!s (e.g., liquid endosperm in coconut).
M Phase Significance of Mitosis
cell division or mitosis most dramatic period Mitosis Mitosis
- equational division
' interphase ( resting phase) Subdivided
starts(karyokinesis) 7 ends (cytokinesis)
reorganisation a! ce! components
diploid daughter ce!s ↓ ↓
haploid ce!
nuclear division cytoplasm division diploid ce!s only
G1 phase (Gap 1)
l parent Csome lower plants,
S phase (Synthesis) equational division chromosomes same
genetica!y same insectsS
Preparation progeny ce!s
v W G2 phase (Gap 2)
Karyokinesis involves 4 stages
ce! growth DNA replication
Prophase cell repair restore nucleo-
G1 phase S or synthesis phase Metaphase Prophase cytoplasmic ratio
do not
↑
↑
interval -"
mitosis DNA synthesis or replication
Anaphase show multicellular
organisms epidermis upper layer Zygotene ⑤
- Mitosis Significance
Telophase cell replace
DNA replication initiation golgi growth
↓ -
-
gut lining bivalent or tetrad
ER chromosomes pairing (synapsis)
metabolica!y active DNA doubles no increase in chromosome nucleolus meristematic tissues blood cells
apical H lateral cambium
continuously grows nuclear envelope
homologous chromosomes
no DNA replication If 2C then 4C If 2n then also 2n Electron micrographs synaptonemal complex
·
All life
initiation of chromosomal condensation
Leads to
compact mitotic chromosomes !]).
I
Meiosis
.
G2 phase replicate DNA In nucleus 2 chromatids with centromere
proteins synthesised
In animal
cells E duplicate centriole In cytoplasm
chromosome untangled
During
chromatin condensation centrosome
move
ce! opposite poles
2 asters with spindle "bres
Pachytene
ce! growth continues gametogenesis in plants and animals
forms
G1 S G2 mitotic apparatus
Male ce! (2n) ↳ Sperm (n)
Fertization
Chromosome 2n 2n 2n
Female ce! (2n) 7
Egg (n) Zygote (2n)
DNA 4C
Metaphase
2C 4C Chromosome half
Diploid Haploid Diploid
spindle "bres
-
Centromere
-
7 one pole ⑪
synaptonemal
complex
Some No ce! division Both meiosis1 4 chromatids( bivalent
adult animals r
chromatid nuclear & Ce! division
chromosomes ) clearly as tetrads recombination nodules
(e.g heart ce!s) kinetochore meiosis 2
inactive stage Disc shapeC -
sister chromatid
·
only once enzyme {recombinase}
no proliferate
1x
cell division DNA replication
injury or cell death replace ce!s S phase
opposite pole
↑
metabolically active Attach identical sister b4 meiosis I
quiescent stage (GO) If needed then cell division spindle "bres chromatids
Some exit G1 phase metaphase plate Diplotene dissolution separation
a! chromosomes at equator
disintegration
complete
nuclear envelope
Cell
·
In animals plants
condensation chromosomes synaptonemal recombined homologous
homologous chromosomes +
mitotic ce! division mitotic ce! division mitotic ce! division
chromosomes morphology easily studied - Germ cell non-sister chromatids
complex chromosomes bivalents
Somatic cell except at crossovers sites
Only But some N Both =2 haploid cells X-shaped
Anaphase Meiosis
Mitosis some vertebrates(oocytes ) diplotene for months/ yrs
haploid ce!s
diploid somatic ce!s eg.male honey bees haploid & diploid ce!s Equational division 46 M 1 Reductional division
46
Centromeres split and chromatids separate 46
-
46 ↳
23 M2 Equational division
Diakinesis
23
Chromatids move to opposite poles 2 diploid ce!s xLd7
23 23 23 23 like mitoti division equal chromosome chiasmata terminalisation
If 2n then 4n
-
- >
nucleolus disappears
4 haploid ce!s nuclear envelope broken
chromosomes separation
