Cell Cycle and Cell Division

Cell Cycle and Cell Division - Topics, Definition And Phases of Cell Cycle

Edited By Irshad Anwar | Updated on Nov 26, 2024 02:46 PM IST

This chapter Cell Cycle and Cell Division in Class 11 Biology is based on the theory of how cells grow and divide. Every living thing grows, develops, and reproduces. The chapter mainly covers the various phases of the cell cycle, such as interphase and the mitotic phase, and two types of cell division, mitosis and meiosis. It is a highly important chapter for all those exams like NEET and AIIMS Nursing for which biology is a major subject. This article covers important key terms and concepts related to the cell cycle and its various stages, type of cell division, and NEET questions frequently asked in exams on cell cycle and cell division.

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This Story also Contains

Important Topics of Cell Cycle and Cell Division
Overview of the Chapter
Cell Cycle and Cell Division
Cell Cycle and Cell Division Notes
Events of Cell Cycle
Stages of the Cell Cycle
Cell Division Importance
Tips, Tricks, and Strategies to Prepare for Cell Cycle and Cell Division
Types of Questions Asked on Cell Cycle and Cell Division

Cell Cycle and Cell Division - Topics, Definition And Phases of Cell Cycle

Important Topics of Cell Cycle and Cell Division

Phases of the Cell Cycle
Regulation of the Cell Cycle
Importance of Cell Division
Important Concepts - Mitosis, Meiosis, Interphase

Overview of the Chapter

The chapter on Cell Cycle and Cell Division in Class 11 Biology deals with the basic processes in which cells grow, replicate and divide. That includes the interphase G1, S, and G2 phases, and the mitotic phase includes mitosis and meiosis, which is required for the formation of gametes. The chapter underlines the importance of regulatory checkpoints that ensure proper cell division, which goes to health and prevent diseases like cancer.

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The cell cycle is a series of events which happens when the cell grows and divides. It is a process by which a cell divides into daughter cells after distributing its genetic material and cytoplasm. The cell cycle is an important part of cellular reproduction and is an integral part of the larger cell cycle.

Some of the key features of the cell cycle are mentioned below:

The longest phase of the cell cycle is interphase in which the DNA replicates itself.
There are three phases of interphase G1 Phase, S Phase and G2 Phase.
In the mitotic phase, the cell divides into two daughter cells.
The G0 phase is also called the resting or quiescent phase as the cell either exits the cycle temporarily or permanently.
The cell cycle is essential for growth tissue repair and asexual reproduction in unit cellular organisms.
An average human cell cycle lasts about 24 hrs.
The cell cycle is strictly regulated which ensures that accurate DNA replicates for the division.

Cell Cycle and Cell Division Notes

A frog zygote was studied by Prevost and Dumas (1824) while they discovered the cell cycle. This is a series of steps a cell passes through to divide and produce new cells. It is the entire process by which a population of cells grows and develops with the help of one single parent cell. Some of the important historical context about the cell cycle and its development is discussed below in the table:

Year	Events
1824	Prevost and Dumas first observed cell division in frogs.
1830s	Schleiden and Schwann proposed Cell Theory which states that all life is made up of cells.
1855	Rudolf Virchow stated Omnis cellula e cellula which means the cells arise from pre-existing cells.
1879	Walter Fleming for the first time described mitosis
20th Century	Molecular biology discovered DNA and its regulatory proteins that control the cell cycle.

Events of Cell Cycle

The cell cycle and cell division class 11 chapter explains the chain of events and each one of them is important. All the important events and their significance in the replication process are discussed below in the table.

Events	Explanation
G1 Phase (Gap 1)	The cell doubles itself and produces protein. The cell monitors the environment and prepares itself for the division.
S Phase ( Synthesis)	DNA is replicated and the genetic material is doubled. Chromosomes are of the same number in this stage.
G2 Phase ( Gap 2)	The cell continues to grow and prepare itself for mitosis by synthesizing the protein.
Mitosis ( M Phase)	The cell divides into two nuclei and the chromosomes are separated by spindle fibers. They are divided into 4 stages: Prophase Metaphase Anaphase Telophase
Cytokinesis	The cytoplasm divides into two daughter cells which develop a cleavage and a furrow is formed.
G0 Phase (Resting)	Some cells exit the phase permanently while some remain metabolically active but do not divide.
Checkpoints	Checkpoints are G1, G2 and metaphase to ensure DNA replication. This prevents errors like DNA damage or incomplete replication.
Duration	24hrs in humans

Diagram of the Cell Cycle

The diagrammatic representation of the cell cycle will help you to have a better understanding of every stage and process involved in the replication.

Cell cycle

Stages of the Cell Cycle

During the process of dividing, a cell must accomplish a few important tasks: It must grow, duplicate its genetic material (DNA), and physically split into two sister cells. These tasks are performed in an organized, predictable manner by the cells, which is known as the cell cycle. Because the two daughter cells can start the same process over again from the beginning to the end of each round, the cell cycle is a cycle, not a linear pathway.

The stages of the cell cycle are divided into two major phases, eukaryotic cells or cells with a nucleus, interphase and mitotic (M) phase. Some of the important stages are mentioned below:

G1 Phase: The cell doubles its organelles and prepares itself for DNA replication.
S Phase: DNA replication takes place with the formation of two sister chromatids.
G2 Phase: The cell continues the growth for the final preparation of mitosis.
M Phase: Mitosis takes place which is followed by cytoplasmic division or Cytokinesis.

Cell Division Importance

Cell division takes place through mitosis and meiosis and is one of the very important events for the growth and repair of the body tissues and muscles. Apart from this, it is also very important for reproduction in organisms. Some of the major importance of cell division is discussed below:

In mitosis, diploid daughter cells are produced with identical genetic material.
It supports growth and tissue repair.
The cell division also ensures that there is the growth of multicellular organisms and restoration of the nucleus cytoplasm ratio.
Due to cell division damaged and dead cells are replaced with healthy ones. This is usually done by the skin, gut lining and blood cells.
Due to cell division, there is continuous plant growth through lateral and apical meristematic tissues.
Due to cell division, there is also preservation of chromosomes. This is usually done in sexually reproducing organisms and increases the genetic variation.

Diagram of the Cell Division

The diagram of cell division given below will help you to have a better understanding of every stage involved in the cell division cycle.

Cell Division

Cell Cycle and Cell Division NEET Questions

Here are some cell cycle and cell division MCQ which students can practice after going through class 11 biology cell cycle and cell division notes:

Ques: What is the longest phase of the cell cycle?

A) G1 Phase
B) S Phase
C) G2 Phase
D) M Phase

Ans: A) G1 Phase

Ques: During which phase of the cell cycle does DNA replication occur?

A) G1 Phase
B) S Phase
C) G2 Phase
D) M Phase

Ans: B) S Phase

Ques: Which of the following statements is true regarding meiosis?

A) It produces two identical daughter cells.
B) It occurs in somatic cells.
C) It reduces the chromosome number by half.
D) It is a single-division process.

Ans: C) It reduces the chromosome number by half.

Ques: What is the role of cyclins in the cell cycle?

A) To assist in DNA replication
B) To regulate the cell cycle
C) To promote cell differentiation
D) To carry nutrients across the cell membrane

Ans: B) To regulate the cell cycle

Ques: In which phase do chromosomes align at the cell's equator during mitosis?

A) Prophase
B) Metaphase
C) Anaphase
D) Telophase

Ans: B) Metaphase

Ques: Which checkpoint assesses DNA damage before the cell proceeds to mitosis?

A) G1 Checkpoint
B) G2 Checkpoint
C) M Checkpoint
D) S Checkpoint

Ans: B) G2 Checkpoint

For more practice, students can refer to resources that provide lists of questions, including cell cycle and cell division questions and answers PDF and cell cycle and cell division MCQ with answers. These resources can greatly help in preparation for exams like NEET.

Tips, Tricks, and Strategies to Prepare for Cell Cycle and Cell Division

It's hard to remember everything in a single go. We made the entire problem easy. Some of the tricks regarding Cell Cycle and Cell Division are given below which you can use to memorise the important points.

Cell Cycle Stages

GSMI

G: G1 Phase (Growth)
S: S Phase (Synthesis of DNA)
G: G2 Phase (Preparation for Mitosis)
M: M Phase (Mitosis and Cytokinesis)
I: Interphase (includes G1, S, and G2)

Key Events in Mitosis

P MAT

P: Prophase (Chromosomes condense, spindle apparatus forms)
M: Metaphase (Chromosomes align at the cell equator)
A: Anaphase (Sister chromatids are pulled apart)
T: Telophase (Nuclear envelopes reform around each set of chromosomes)

Importance of Cell Division

GREAT M

G: Growth of multicellular organisms
R: Repair of damaged tissues
E: Equal distribution of genetic material
A: Asexual reproduction (in some organisms)
T: Tissue regeneration
M: Maintenance of nucleus-cytoplasm ratio

Types of Questions Asked on Cell Cycle and Cell Division

During the preparation of the exam, there are different types of questions asked about Cell Cycle and Cell Division in different forms. The table given below contains the different patterns of questions and their weightage in different exams.

Exam Type	Types of Questions	Weightage
CBSE	Short answer questions on phases of the cell cycle, processes of mitosis and meiosis, and significance of checkpoints.	5-6%
NEET	MCQs focus on the stages of the cell cycle, mechanisms of cell division, and regulatory proteins involved.	3-5%
AIIMS	Assertion and reason questions regarding cell cycle phases, differences between mitosis and meiosis, and their biological significance.	3-4%
Nursing Entrance Exams	Scenario-based questions addressing the relevance of cell division in growth, repair, and reproduction.	2-3%
Paramedical Exams	True/False questions and multiple-choice questions on characteristics of mitosis and meiosis, and the implications of cell cycle regulation.	1-3%

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Frequently Asked Questions (FAQs)

1. What is cell cycle and cell division?

The cell cycle is a series of stages that a cell goes through to grow, replicate its DNA, and divide into two new cells. It includes interphase (G1, S, and G2 phases) and mitosis, the process of cell division that creates identical daughter cells.

2. How many stages are there in mitosis?

During the cell cycle, there are four important stages:

1. Interphase

2. Prophase

3. Metaphase

4. Anaphase

5. Telophase

6. Cytokinesis

Of which, prophase, metaphase, anaphase, and telophase are 4 stages of M- phase.

3. The stages of a cell cycle are as follows:

Following are the phases of the cell cycle:

Phases including G1, S, and G2 are referred to as the interphase.
In the mitotic phase, there are prophases, metaphases, anaphases, and telophases.
Cytokinesis - The cytoplasm divides during this phase.

4. Who first discovered the cell cycle?

During the 19th century, Walther Flemming discovered the cell cycle. The professor at the Institute of Anatomy was responsible for this discovery.

5. How important is it for cells to divide?

Here are some reasons why cell division is critical:

Cell division promotes the survival and growth of organisms.
Maintaining the number of chromosomes.
Cell renewal in damaged tissues.

6. At what point in the cell cycle is the most important?

Cell division occurs during interphase. The cell stays in interphase for the longest time. Cells go through this phase to prepare for division. This is when the cell grows and replicates.

7. How many questions come from cell cycle and cell division in NEET?

In the NEET exam, the Cell Cycle and Cell Division chapter has a weightage of about 7-8%, which usually covers around 3 to 5 questions.

8. What is the difference between cell cycle and cell division?

The cell cycle refers to the complete series of events a cell follows to grow and prepare its DNA to replicate and divide, with some phases being interphase-G1, S, G2, and others mitotic phase-mitosis. The cell division process refers to when a parent cell divides to produce two or more daughter cells which is known as mitosis or meiosis.

9. What are the 4 stages of the cell cycle?

The cell cycle consists of four main stages:

G1 Phase (Gap 1): The cell grows and performs normal functions while preparing for DNA replication.
S Phase (Synthesis): The cell replicates its DNA, producing two identical copies of each chromosome.
G2 Phase (Gap 2): The cell continues to grow and checks for DNA errors, preparing for division.
M Phase (Mitosis): The cell divides, separating its duplicated DNA into two daughter cells, followed by cytokinesis, where the cytoplasm divides.