Definition of Cell Cycle and Cell Division. Learn about what is cell division by mitosis? Different phases and stages of cell cycle. Get NCERT notes about cell regulations

1. Phone :- 0141 400482 Exampraxis.com Email :- support@exampraxis.com
Introduction :
A close analysis of Botany Chapter ‘Cell Cycle and Cell Division’ based on previous 22 years
exam questions ( between 2000-2021) suggests that suggests that overall weightage of this
chapter in the NEET Exam is 3 % which means on an average 2-4 questions are asked from this
chapter each year.
The high priority topics of the chapter ‘Cell Cycle and Cell Division’ from which there is greater
chance of occurrence in the NEET Exam are listed below.
1.Phases of cell cycle
2.Mitosis
3.Meiosis
4.Cell Cycle
The students are advised to practice at least 200-300 questions from the high priority topics
mentioned above.

2. Phone :- 0141 400482 Exampraxis.com Email :- support@exampraxis.com
Noteworthy Points of the Chapter :
1. Sexually reproducing organisms starts their life cycle from a single-cell, zygote.
2. The stages through which a cell passes from one division to the next is called cell cycle.
3. Yeast progresses through the cell cycle in 90 minutes.
4. The cell cycle is divided into two phases interphase and M-Phase.
5. Nuclear division is known as karyokinesis while cytoplasm division is known as cytokinesis.
6. In cell cycle, the resting phase during which cell is preparing for cell division is called
interphase, divided into G1, S and G2 phases.
7. In G1 phase synthesis of RNA, ATP, proteins and nucleotides occur, most of the cell
organelles duplicate.
8. During S phase, amount of DNA per cell doubles.
9 In G2 phase, golgi, mitochondria and chloroplast duplicate and synthesis of RNA, proteins
etc. occur.
10. If the cell has 2n number of chromosomes at G1, then number of chromosomes after S phase
will remain 2n.
11. G0 phase of the cell cycle is called quiescent stage (cell metabolically active but do not
proliferate).
12. During prophase of M-phase, duplicated centriole begins to move towards the opposite poles
of a cell, chromatin condense, cell organelle start disappearing and nuclear membrane
disintegrate.
13. Kinetochores on surface of centromere serve as the sites of attachment of spindle fibres to
the chromosome.
14. The plane of alignment of chromosome at metaphase is referred to as the metaphase plate.
15. Anaphase stage is characterised by splitting of centromeres and separation of chromatids.

3. Phone :- 0141 400482 Exampraxis.com Email :- support@exampraxis.com
16. Nuclear envelope assembles around chromosome clusters in telophase stage of M-phase.
17. During cytokinesis in a plant cell, formation of cell plate represents middle lamella between
the walls of two adjacent cells. In animals cytokinesis is achieved by cell furrow.
18. During zygotene stage of Prophase I, chromosomes start pairing together. This process of
association is called synapsis.
19. During zygotene stage, the complex formed by a pair of synapsed homologous chromosomes
is called a bivalent.
20. Crossing over occurs during pachytene stage of Prophase I. It is an enzyme-mediated
process and enzyme involved is called recombinase.
21. Crossing-over occurs between non-sister chromatids of homologous chromosomes.
22. The X-shaped structures called chiasmata are seen in diplotene stage. The chiasmata
terminates at diakinesis stage.
23. Mitosis is called equational division whereas meiosis is called reductional division.
24. Number of daughter cells formed after mitosis is 2 and after meiosis is 4.
25. Mitosis helps in healing of wound, cell repair, maintenance of nucleocytoplasmic ratio and
gamete formation in haploid organisms.
26. Meiosis helps in conservation of specific chromosome number across the generation in
sexually reproducing organism and in bringing variations.