Cell cycle | CEE Academy

📚

REASON FOR CELL CYCLE / CELL DIVISION

▢ Core Reason:

•
Cell divides to maintain balance between bulk of cytoplasm and nucleus
•
Cell division restores high surface area : volume ratio
•
Cell division restores high nucleocytoplasmic ratio

▢ Nucleocytoplasmic Ratio:

❖ Formula: Nucleocytoplasmic ratio = Vₙ / Vcyto = Vₙ / (Vcell − Vₙ)

❖ Synonym: Karyoplasmic ratio

❖ Important Points:

•
In a cell going to divide, nucleocytoplasmic ratio decreases
•
Surface area per unit volume also decreases
•
Increase in nucleocytoplasmic ratio indicates increasing cell division activity
•
Smaller cells are metabolically more active due to high nucleocytoplasmic ratio

📚

CHROMOSOME AND DNA AMOUNT

▢ Basic Rule:

•
Every chromosome has 2 chromatids after DNA replication
•
Exception: daughter chromosome has 1 chromatid
•
Chromosome number and DNA amount change differently during cell cycle

Table 1: Chromosome / DNA Recall

Stage	Chromosome Number	DNA Amount	Chromatid Status
G1	2n	2C	1 chromatid / chromosome
S phase	2n	2C → 4C	DNA replication
G2	2n	4C	2 chromatids / chromosome
Metaphase of mitosis	2n	4C	2 chromatids / chromosome
Anaphase of mitosis	4n temporarily	4C	Sister chromatids separate as daughter chromosomes
After mitosis	2n in each daughter cell	2C each	1 chromatid / chromosome
Metaphase-I	2n	4C	2 chromatids / chromosome
Anaphase-I	n at each pole	2C at each pole	Centromere not divided; chromatids remain paired
After meiosis-II	n	1C	1 chromatid / chromosome

📚

CELL CYCLE

▢ Definition:

•
Cell cycle = sequence of events between two cell divisions
•
Cell accumulates nutrition and then divides into daughter cells
•
Cell division = process of forming daughter cells from parent cell

▢ Generation Time: Total time taken by parent cell to divide into daughter cells

▢ Main Events:

DNA replication
Nuclear division / karyokinesis
Cytoplasmic division / cytokinesis

▢ Phases:

•
Interphase / I-phase
•
Mitotic phase / M-phase

▢ Sequence:

•
G1 → S → G2 → M
•
S → G2 → M → G1
•
G2 → M → G1 → S
•
M → G1 → S → G2

▢ Duration Points:

•
G1 = most variable phase of cell cycle
•
G2 = shortest phase of interphase
•
M-phase = shortest phase of whole cell cycle

📚

INTERPHASE

▢ Synonyms:

•
I-phase
•
Non-dividing phase
•
Resting phase
•
Metabolic phase
•
Growth phase
•
Preparative phase
•
Invisible phase

▢ Important Points:

•
Longest phase of cell cycle
•
Called resting phase because nucleus is not dividing
•
Actually metabolically / physiologically most active phase
•
Nucleus is largest during interphase
•
Replicated chromosomes are not visible
•
Transcription occurs throughout interphase
•
Transcription rate highest in G1 phase

▢ Subphases:

•
G1 phase
•
S phase
•
G2 phase

📚

G1 PHASE

▢ Synonyms:

•
Gap I
•
Growth I
•
Post-mitotic phase
•
Pre-DNA synthesis phase

▢ Main Nature:

•
Preparatory phase of DNA synthesis
•
Maximum growth occurs in G1 phase
•
Decision of cell division occurs in this phase

▢ Synthesis:

•
RNA: tRNA, mRNA, rRNA
•
Ribosomes
•
Histone protein synthesis starts
•
Bulk histone synthesis occurs in S phase
•
Non-histone proteins
•
Structural proteins
•
Functional proteins
•
Enzymes: DNA polymerase, RNA polymerase

▢ Absent In:

•
Amoeba
•
Slime moulds
•
Yeast

▢ Restriction Point:

•
Also called R-point / checkpoint
•
Present in G1 phase
•
After crossing this point or entering S phase, division becomes compulsory

▢ Non-dividing Cell: Non-dividing cells remain in G1 / enter G0

📚

G0 PHASE

▢ Synonyms:

•
Quiescent stage
•
Quiet stage

▢ Definition: Stage of arrest of cell cycle and onset of differentiation

▢ Examples:

•
Cells of quiescent centre in root tip
•
Skeletal muscle cells
•
Nerve cells
•
RBC

📚

S PHASE

▢ Synonyms:

•
Synthetic phase
•
DNA synthesis phase

▢ Nature:

•
Metabolically most active stage
•
Invisible phase of mitosis because replicated chromosomes are not visible
•
After S phase, cell can enter division without interruption

▢ Synthesis:

•
Replication / synthesis of nuclear DNA
•
DNA replication occurs with DNA polymerase
•
DNA polymerase is active
•
Histone protein synthesis

▢ Chromosome Status: Each chromosome has 2 chromatids after S phase

📚

G2 PHASE

▢ Synonyms:

•
Gap II
•
Growth II
•
Pre-mitotic phase
•
Post-DNA synthesis phase
•
Resting phase of interphase

▢ Events:

•
Replication of cytoplasmic DNA
•
Synthesis of organelles required for M phase
•
Synthesis of tubulin protein for spindle apparatus
•
Energy storage
•
Centriole duplication
•
Cell contains double DNA amount compared to original diploid cell

▢ Special Points:

•
Division of chloroplast and mitochondria starts in G2
•
Division of chloroplast and mitochondria continues up to cytokinesis
•
In meiotic cell division, G2 phase is very short or almost absent

📚

MITOTIC PHASE

▢ Synonyms:

•
M-phase
•
Dividing phase
•
Cell division

▢ Important Points:

•
Shortest phase of cell cycle
•
Includes karyokinesis and cytokinesis

▢ Components:

Table 1: Components of M Phase

Component	Meaning
Karyokinesis	Nuclear division
Cytokinesis	Division of cytoplasm
Cell plate	Plant cytokinesis
Constriction / furrowing	Animal cytokinesis

▢ Types of Cell Division:

•
Amitosis
•
Mitosis
•
Meiosis

📚

AMITOSIS

▢ Synonyms:

•
Direct cell division
•
Incipient cell division
•
Primitive cell division

▢ Features:

•
Division completes without spindle fibre formation
•
Unequal cell division
•
Main method of division in prokaryotic cells
•
Also occurs in some eukaryotic cells like Saccharomyces / yeast
•
Nuclear membrane persists throughout nuclear division

▢ Examples:

•
Budding
•
Fission

📚

MITOSIS

▢ Synonyms:

•
Somatic cell division
•
Indirect cell division
•
Homotype cell division
•
Equational cell division

▢ Special Note: On the basis of DNA, mitosis may be considered reductional in the given note

▢ Best Material: L.S. of onion root tip

▢ Occurrence:

•
Unicellular eukaryotes
•
Multicellular eukaryotes
•
Haploid, diploid and polyploid cells
•
Somatic cells
•
Reproductive cells

▢ Result: Single cell → 2 daughter cells

▢ Mitocyte: Cell undergoing mitosis

▢ Calculations:

Table 1: Mitosis Formulae

Question Type	Formula
Total mitotic divisions/events needed to produce n cells from one cell	n − 1
Number of cells after n generations	2ⁿ
Number of generations to form given cells	2ⁿ = given number

▢ Types Based on Spindle Formation:

Table 1: Types of Mitosis

Type	Feature	Common In
Astral / amphiastral mitosis	Mitosis with spindle fibre formation	Animals
Anastral mitosis	Mitosis without astral spindle formation	Plants

📚

MITOTIC KARYOKINESIS

▢ Stages:

•
Prophase
•
Metaphase
•
Anaphase
•
Telophase

▢ Important Point: All 4 stages occur continuously without stoppage

📚

PROPHASE OF MITOSIS

▢ Key Features:

•
First stage of mitosis
•
Longest stage of mitosis
•
Metabolically most active stage of cell division
•
Chromatin changes into chromosomes
•
Chromosomes become visible
•
Prophase chromosomes = prochromosomes
•
Spiralisation occurs
•
Spiralisation type = plectonemic coiling
•
Cell becomes more viscous
•
Spindle fibre formation starts during late prophase
•
Nuclear membrane disappears during late prophase
•
Nucleoplasm disappears during late prophase
•
Nucleolus disappears during late prophase

▢ Not Visible:

•
Centromere not visible
•
Chromatids not visible

▢ Spindle Fibre:

•
Made of 97% tubulin protein
•
Made of 3% RNA

▢ CEE Trap:

•
Plectonemic coiling → mitotic prophase
•
Paranemic coiling → meiotic prophase

📚

METAPHASE OF MITOSIS

▢ Key Features:

•
Chromosomes are thickest
•
Chromosomes are shortest
•
Centromere visible
•
Chromatids visible
•
Best stage to study chromosomes
•
Metaphase-II is better than metaphase-I for chromosome study
•
Chromosomes arrange in single line at equator
•
Arrangement at equator = metakinesis
•
Single metaphasic / equatorial plate formed
•
Structure, size and number of chromosomes studied
•
Spindle fibre well developed
•
Spindle fibres from opposite poles attach to kinetochore / primary constriction
•
Idiogram / karyotype prepared

▢ Chromatid Count: Number of chromatids per chromosome = 2 in mitosis and meiosis metaphase

📚

ANAPHASE OF MITOSIS

▢ Synonym: Migratory phase

▢ Key Features:

•
Shortest stage of mitosis
•
Inert / less active stage of cell division
•
Best stage to study chromosome shape
•
Centromere divides
•
Sister chromatids separate
•
Sister chromatids move towards opposite poles
•
Each chromosome has 1 chromatid in anaphase
•
Poleward movement occurs due to spindle fibre and centromere
•
Main force for poleward movement generated by centromere
•
Calcium ions promote anaphase

▢ Chromosome Shapes:

•
V-shaped
•
J-shaped
•
L-shaped
•
I-shaped

▢ Special Note: Chromosome number remains same but chromatid number becomes half compared to metaphase

📚

TELOPHASE OF MITOSIS

▢ Synonym: Re-organisation phase

▢ Key Features:

•
Reverse of prophase
•
Nuclear membrane reappears
•
Nucleolus reappears
•
Chromosomes decondense
•
Chromosomes uncoil
•
Chromosomes reach opposite poles
•
Spindle fibres disappear
•
Chromosomes reorganise
•
Cell resumes metabolic activity

▢ Result: Two daughter nuclei with same chromosome number and same DNA amount

📚

CYTOKINESIS

Table 1: Plant vs Animal Cytokinesis

Feature	Plant Cell	Animal Cell
Method	Cell plate formation	Furrowing / constriction
Initiating structure	Golgi body initiates cell plate	Microfilaments form contractile ring
Plane determined by	Microtubules	Microfilaments
Growth direction	Centrifugal	Centripetal
Final result	Phragmoplast → cell plate → cell wall	Cleavage furrow divides cytoplasm

▢ Plant Cell Plate Formation:

•
Spindle fibres aggregate at equator
•
Golgi body initiates cell plate formation
•
Cell plate later converts into phragmoplast and finally cell wall

📚

SPECIAL POINTS OF MITOSIS

▢ Daughter Cells:

•
Same amount of DNA as parent cell
•
Same number of chromosomes as parent cell
•
Genetically identical cells

▢ C-Mitosis:

•
Colchicine-treated mitosis
•
Colchicine = mitotic poison
•
Temporarily stops mitotic division
•
Inhibits spindle fibre formation
•
Breaks microtubules
•
Arrests cell division at metaphase
•
Produces polyploidy

▢ Uncontrolled Mitosis: Leads to neoplasia

▢ Example Calculations:

Table 1: CEE Calculation Examples

Question	Answer
Mitotic division events needed to form 64 cells	64 − 1 = 63 total division events
Generations needed to form 32 cells	2ⁿ = 32 → n = 5
Bacteria divides every 20 min; cells after 2 hr	2 hr = 120 min; 120/20 = 6 generations; 2⁶ = 64
Bacteria fills cup in 60 min, divides every 1 min; half cup time	59 min
Bacteria fills cup in 60 min, divides every 3 min; half cup time	57 min

📚

SIGNIFICANCE OF MITOSIS

▢ Points:

•
Growth of organism
•
Maintenance of somatic cells
•
Repair of somatic cells
•
Maintains genetic stability
•
Avoids ageing by replacing old cells
•
Produces genetically identical cells resembling zygote
•
Restores surface area : volume ratio
•
Restores nucleocytoplasmic ratio by dividing mature cell into smaller cells

📚

MEIOSIS

▢ Synonyms:

•
Reductional cell division

▢ Introduction:

•
Common in germ cells / reproductive cells
•
Single cell divides to form 4 daughter cells
•
Occurs in pollen mother cell
•
Two divisions of nucleus
•
Only one division of chromosome
•
Meiotic cell = meiocyte
•
Meiocyte divides once in lifetime
•
Meiosis is never followed by meiosis
•
Meiosis can be followed by mitosis
•
In alternation of generation, meiosis is always followed by fusion / fertilization
•
Occurs in diploid and polyploid cells
•
Never occurs in haploid cells

▢ Best Material:

•
Anthers of onion
•
Tradescantia
•
Anther / microsporangium / microspore mother cell

▢ Result Compared to Diploid Parent:

•
Same amount of DNA according to given note
•
Half number of chromosomes

▢ Gamete Production:

Table 1: Spermatocyte / Oocyte Output

Starting Cell	Output
1 primary spermatocyte / 2n	4 sperms
1 primary oocyte / 2n	1 egg
1 secondary spermatocyte / n	2 sperms
1 secondary oocyte / n	1 egg

▢ Double Division:

•
Meiosis-I
•
Meiosis-II

📚

MEIOSIS-I

▢ Nature: Reductional division

▢ Components:

•
Karyokinesis
•
Cytokinesis

▢ Stages:

•
Prophase-I
•
Metaphase-I
•
Anaphase-I
•
Telophase-I

📚

PROPHASE-I

▢ Importance:

•
Longest phase of meiosis
•
Most complex phase of meiosis
•
Longest and most complex phase = Prophase-I

▢ Substages:

Table 1: Prophase-I Substages

Stage	Main Character
Leptotene	Bouquet formation
Zygotene	Synapsis
Pachytene	Crossing over; chiasmata formation starts
Diplotene	Chiasmata visible / completed; terminalisation starts
Diakinesis	Terminalisation completes

📚

LEPTOTENE

▢ Features:

•
Chromosomes are thread-like
•
Chromosomes show beads called chromomeres
•
Bouquet formation occurs
•
Called bouquet stage
•
Best stage for observation of chromomere

▢ Trap:

•
Chromomere = bead structure in meiotic chromosome
•
Nucleosome = bead structure in chromatin

📚

ZYGOTENE

▢ Main Event: Synapsis

▢ Synapsis:

•
Lengthwise pairing of homologous chromosomes
•
Precise chromomere-to-chromomere pairing
•
Also called syndesis / zipping
•
Occurs in zipper-like fashion
•
May begin at centromere, ends or any point

▢ Synaptonemal Complex:

•
Protein complex favouring synapsis
•
Tripartite structure

▢ Bivalent:

•
Each paired homologous chromosome pair = bivalent
•
Exists as dyad / 2-stranded stage in zygotene
•
Bivalent produced in diploid and allopolyploid
•
Multivalent produced in autopolyploid
•
Number of bivalents = half total chromosomes in diploid cell

▢ Other Features:

•
Chromosomes thicken
•
Chromosomes shorten

📚

PACHYTENE

▢ Importance:

•
Longest substage of Prophase-I
•
Most important substage of Prophase-I
•
Chromosomes are thickest
•
Morphological details of chromosome best studied

▢ Crossing Over:

•
Exchange of genetic material / chromatid segment / DNA / genes
•
Occurs at 4-stranded stage
•
Equal exchange between non-sister chromatids of homologous chromosomes
•
Major source of continuous variation in sexually reproducing organisms
•
Ultimate source of variation = mutation
•
Mutation produces discontinuous variation

▢ Crossing Over Frequency: Single crossing over > double crossing over > triple crossing over

▢ Enzymes:

Table 1: Enzymes of Crossing Over

Enzyme	Function
Endonuclease	Breakdown / nicking
Unwindase	Separation
Ligase	Rejoining

▢ Tetrad Formation:

•
Sister chromatids become visible
•
Bivalent exists as tetrad
•
Tetrad contains 2 homologous chromosomes
•
Tetrad contains 4 chromatids
•
Tetrad contains 2 centromeres
•
Tetrad contains 4 kinetochores

▢ Synapsis Status:

•
Synapsis mature
•
Synaptonemal complex mature
•
Bivalent mature

📚

DIPLOTENE

▢ Features:

•
Chiasmata formation takes place / becomes clearly visible
•
Synaptonemal complex starts dissolving except at chiasmata
•
Chiasmata indicates crossing over
•
Terminalisation starts

▢ Important Clarification:

•
Chiasmata formation starts during pachytene
•
Chiasmata clearly visible during diplotene

▢ Lampbrush Chromosomes:

•
Profuse decondensation occurs
•
Seen in female species producing yolky eggs
•
Examples: all vertebrates and some invertebrates

▢ Human Female: Ovum remains in diplotene stage from birth to puberty; diplotene is longest in human female

📚

DIAKINESIS

▢ Features:

•
Chiasmata disappear due to terminalisation
•
Terminalisation completes
•
Chiasmata move from centromere to telomere in zipper-like fashion
•
At end, each chromosome has two chromatids = dyad
•
Spindle fibre formation starts
•
Nuclear membrane starts disappearing
•
Nucleolus starts disappearing
•
Nucleoplasm starts disappearing

▢ Terminalisation Note:

•
Terminalisation starts before / by diakinesis as per note sequence
•
Terminalisation occurs and ends during diakinesis

📚

SYNAPTONEMAL COMPLEX

▢ Features:

•
Feature of meiotic Prophase-I
•
Characteristic protein mentioned = ubiquitin
•
First observed by Moses
•
Appears in zygotene
•
Persists in pachytene
•
More clear in pachytene
•
Disappears during diplotene
•
Helps proper pairing of homologous chromosomes
•
Helps recombination

📚

METAPHASE-I

▢ Features:

•
Paired homologous chromosomes arrange at equatorial plane
•
Arrangement = congression
•
Chromosomes arrange in two distinct lines
•
Double metaphase plate formed
•
Spindle fibres appear
•
Each chromosome has 2 chromatids and 1 centromere

📚

ANAPHASE-I

▢ Features:

•
Separation of maternal and paternal homologous chromosomes
•
Separation = disjunction
•
Separated chromosomes = univalents / dyads
•
Centromere does not divide
•
Chromosome number reduces to half
•
Chromatid number remains same compared to metaphase-I

📚

TELOPHASE-I

▢ Features:

•
Similar to mitotic telophase
•
Daughter nuclei form after first meiotic division
•
Followed by cytokinesis

📚

INTERKINESIS

▢ Definition: Brief intrameiotic interphase between meiosis-I and meiosis-II

▢ Important Point:

•
No S phase
•
No DNA synthesis
•
Occurs between meiosis-I and meiosis-II

📚

MEIOSIS-II

▢ Synonym: Meiotic mitosis

▢ Nature: Similar to mitosis

▢ Stages:

•
Prophase-II
•
Metaphase-II
•
Anaphase-II
•
Telophase-II

▢ Components:

•
Karyokinesis
•
Cytokinesis

▢ Cytokinesis Types:

Table 1: Cytokinesis in Meiosis

Type	Wall Formation	Tetrad Formed
Successive type	Both meiosis-I and meiosis-II followed by wall formation	Isobilateral tetrads
Simultaneous type	Meiosis-I not followed by wall formation; wall formation after meiosis-II	Tetrahedral tetrads

📚

SIGNIFICANCE OF MEIOSIS

▢ Points:

•
Maintains constant chromosome number in sexually reproducing organisms
•
Crossing over causes recombination
•
Recombination has role in evolution
•
Shows basic relationship among organisms

▢ Numerical Points:

•
Number of cytokinesis in meiosis = 3
•
1 cytokinesis in meiosis-I + 2 cytokinesis in meiosis-II
•
Number of spindles in meiosis = 3
•
1 spindle in metaphase-I + 2 spindles in metaphase-II
•
Chromatids per chromosome = 2 in metaphase of mitosis / meiosis
•
Chromatids per chromosome = 1 in anaphase of mitosis
•
Chromatids per chromosome = 2 in anaphase-I of meiosis

📚

MITOSIS VS MEIOSIS

Table 1: High-Yield Comparison

Feature	Mitosis	Meiosis
Common site	Somatic cells	Germ / reproductive cells
Best material	L.S. onion root tip	Onion / Tradescantia anther
Number of divisions	One	Two
Daughter cells	2	4
Chromosome number	Maintained	Reduced to half
Genetic nature	Identical daughter cells	Variable daughter cells due to crossing over
Synapsis	Absent	Present in zygotene
Crossing over	Absent	Present in pachytene
Centromere division	Anaphase	Anaphase-II; not in anaphase-I
Function	Growth, repair, maintenance	Gamete formation, variation, chromosome number maintenance

Q1.

Chiasmata formation takes place in [MOE 2058]

📅MOE 2058

Q2.

Meiosis occurs in [MOE 2055]

📅MOE 2055

Q3.

Chromosomes are seen distinctly during [BPKIHS 1997]

📅BPKIHS 1997

Q4.

Mitosis can be clearly observed from: [BPKIHS 1997]

📅BPKIHS 1997

Q5.

The smallest unit of crossing over is [BPKIHS 1998]

📅BPKIHS 1998

Q6.

When only G, phase is operating and others are no operating the phase is [BPKIHS 1998]

📅BPKIHS 1998

Q7.

Synapsin occurs in which stage: [MOE - 2008]

📅MOE - 2008

Q8.

The no. of chromatids in a chromosomes at metaphase is: [MOE-2002]

📅MOE-2002

Q9.

In meiosis cell division, nuclear membrane disappear and chromosomes are separated during: [MOE-2053)

📅MOE-2053)

Q10.

The two daughter cells produced at the end of meiosis when compared to the parent diploid cells will have: [IOM-2004)

📅IOM-2004)

Q11.

Nucleus has maximum size during: [IOM- 20]

📅IOM- 20%

Q12.

Which of the following is associated with division? [IOM-200]

📅IOM-200

Q13.

How many times does a simple cell divide mitotical to form 32 cells? [IOM-20]

📅IOM-20

Q14.

In which stage does centromere divide? [IOM- 20]

📅IOM- 20

Q15.

The inherent capacity of a cell to regenerate a total plant is called. [IOM- 195

📅IOM- 195

Q16.

Interphase, chromatin under electron microscope refers to: [BPKIHS 200]

📅BPKIHS 200

Q17.

The mitosis can be readily observed in: [BPKIHS 200)

📅BPKIHS 200)

Q18.

During meiosis, which is correct? [BPKIHS 2001

📅BPKIHS 2001

Q19.

During which phase chromatids are clearly seen: [BPKIHS 200]

📅BPKIHS 200%

Q20.

Homologous chromosome separate during: [BPKIHS 2002

📅BPKIHS 2002

Q21.

During meiosis gametes produced are: [BPKIHS 2002)

📅BPKIHS 2002)

Q22.

No. of chromosomes in sister cells immediately after mitotic metaphase are: [BPKIHS 2003)

📅BPKIHS 2003)

Q23.

Karyokinesis is the division of:

📅BPKIHS 2005

Q24.

Terminalisation takes place during:

📅BPKIHS 2005

Q25.

The site where meiosis occur in a plant is:

📅BPKIHS 2006

Q26.

A cell stops growing due to storage of nutrients, this would happen in:

📅BPKIHS 2007

Q27.

In cell division replication of DNA occurs in

📅IE - 2002

Q28.

During the start of mitosis the condensed chromosome contains 2

📅IE - 2002

Q29.

Which of the following is the part of mitosis in seed plants?

📅IE - 2002

Q30.

During cell cycle, two molecules of DNA are present in chromosome during

📅IE -2003

Q31.

The transfer of genes from one chromosome to another during synapsis, is termed as:

📅IE - 2004

Q32.

Crossing over occurs during

📅IE - 2005

Q33.

Replication of DNA occurs during

📅IE - 2005

Q34.

The region of attachment of chromosome to spindle fibre is called

📅IE - 2005

Q35.

Segregation of dominant and recessive genes occur during:

📅IE - 2008

Q36.

The point at which crossing over takes place is [BPKIHS - 2016, 2012]

📅BPKIHS - 2016, 2012

Q37.

The phase of cell cycle in which nucleolus and nuclear membrane disappear is [BPKIHS - 2016)

📅BPKIHS - 2016)

Q38.

What is the correct order of prophase I of meiosis I? [BPKIHS - 2013]

📅BPKIHS - 2013

Q39.

Chromosomes becomes distinct and nucleolus as well as nuclear membrane disappears is [BPKIHS - 2012]

📅BPKIHS - 2012

Q40.

Centrosome helps in [BPKIHS - 2011]

📅BPKIHS - 2011

Q41.

Shortest phase of cell cycle is: [BPKIHS - 2010]

📅BPKIHS - 2010

Q42.

Correct sequence of cell cycle is

📅IOM-2014

Q43.

The main significance of M-phase of the cell cycle is

📅IOM-2013

Q44.

Terminalization occurs in

📅IOM-2016

Q45.

The mitotic poison is

📅IOM-2012

Q46.

In which stage chromosome are arranged in equator?

📅IOM-2012

Q47.

In meiosis, bivalent is attached to spindle fiber at

📅IOM-2012

Q48.

The amount of DNA doubles in which mitotic phase

📅MOE 2014

Q49.

At what stage of mitotic division, formation daughter nuclei takes place?[MOE 2016

📅MOE 2016

Q50.

The pairing (synapsid) of chromosome occurs in the following stage of meiosis-I [MOE 2068)

📅MOE 2068)

Q51.

In which stage of the meiotic cell division crossing over occurs? [MOE 2010)

📅MOE 2010)

Q52.

Centromere completely divides into two separate chromatids at [MOE 2010)

📅MOE 2010)

3Cell cycle

Table 1: Chromosome / DNA Recall

Table 1: Components of M Phase

Table 1: Mitosis Formulae

Table 1: Types of Mitosis

Table 1: Plant vs Animal Cytokinesis

Table 1: CEE Calculation Examples

Table 1: Spermatocyte / Oocyte Output

Table 1: Prophase-I Substages

Table 1: Enzymes of Crossing Over

Table 1: Cytokinesis in Meiosis

Table 1: High-Yield Comparison

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