Cell division is a fundamental biological process through which a parent cell divides into two or more daughter cells. This process is essential for growth, development, and maintenance of all living organisms. There are two primary types of cell division: mitosis and meiosis.
Types of Cell Division
1. Mitosis
Definition: Mitosis is the process of nuclear division that results in two genetically identical daughter cells, each with the same number of chromosomes as the parent cell.
Purpose:
Growth and development
Tissue repair and regeneration
Asexual reproduction in some organisms
Phases of Mitosis:
Prophase: Chromatin condenses into visible chromosomes; the nuclear envelope begins to break down.
Metaphase: Chromosomes align at the cell's equatorial plane (metaphase plate).
Anaphase: Sister chromatids are pulled apart to opposite poles of the cell.
Telophase: Nuclear envelopes reform around each set of chromosomes; chromosomes begin to de-condense.
Cytokinesis: The cytoplasm divides, resulting in two separate daughter cells.
2. Meiosis
Definition: Meiosis is a specialized form of cell division that reduces the chromosome number by half, producing four genetically diverse haploid cells (gametes).
Purpose:
Sexual reproduction (formation of sperm and eggs)
Increases genetic diversity through recombination and independent assortment.
Phases of Meiosis:
Meiosis I:Prophase I
Meiosis II (similar to mitosis):Prophase II, Metaphase II, Anaphase II, Telophase II, and Cytokinesis result in four haplo
id cells.
Importance of Cell Division
Growth and Development: Mitosis allows organisms to grow from a single fertilized egg into complex multicellular beings.
Tissue Repair: Mitosis replaces damaged or dead cells, maintaining tissue integrity.
Genetic Diversity: Meiosis introduces genetic variation essential for evolution and adaptation in populations.
Regulation of Cell Division
Cell division is tightly regulated by various mechanisms to ensure proper growth and prevent uncontrolled proliferation (cancer). Key regulatory proteins include:
Cyclins and cyclin-dependent kinases (CDKs)
Tumor suppressor genes (e.g., p53)
Oncogenes
Conclusion
Cell division is a critical biological process that underpins growth, reproduction, and maintenance in living organisms. Understanding both mitosis and meiosis is essential for studying biology, genetics, and medicine.
An ICT training program was organized at the Director Institutions of Edappal, aimed at equipping educators with advanced digital tools and strategies for effective teaching. The training witnessed active participation from faculty members of self-financing colleges and teachers from CBSE schools, reflecting the growing need for technological integration in education.
Objectives:
1. Enhance participants’ understanding of ICT tools in education.
2. Train educators to incorporate digital resources effectively in their teaching methodologies.
3. Promote collaboration and knowledge-sharing among educators from diverse institutions.
Participation:
Institutions:
Representatives from self-financing colleges and CBSE schools in and around Edappal participated in the event.
Participants:
The training program included [exact number] participants, comprising:
Professors and lecturers from self-financing colleges.
Teachers from various CBSE schools, covering multiple disciplines.
Role of Dr. K. S. Sajan:
As the resource person, Dr. K. S. Sajan delivered a comprehensive session on:
1. The integration of ICT tools for enhancing classroom engagement.
2. Use of Learning Management Systems (LMS) like Moodle for effective course delivery.
3. Best practices in e-content development tailored for diverse educational needs.
4. Strategies for utilizing online platforms for assessments and feedback.
Key Highlights:
Hands-on training sessions enabled participants to practically apply ICT tools.
Interactive discussions on challenges faced in digital adaptation and solutions to overcome them.
Demonstrations of case studies showcasing successful ICT integration in educational settings.
Feedback:
Participants appreciated the clarity and expertise of Dr. Sajan in addressing practical challenges related to ICT integration. They found the session engaging, insightful, and directly applicable to their teaching contexts.
Conclusion:
The ICT training program successfully met its objectives, empowering educators to adapt to the evolving technological landscape in education. The active involvement of participants from self-financing colleges and CBSE schools underscored the program's relevance and impact.
Acknowledgment:
The Director Institutions, Edappal, extend their gratitude to Dr. K. S. Sajan for his valuable contribution as a resource person and for sharing his expertise with the participants.
1. Students will understand the structures and purposes of basic
components of prokaryotic and eukaryotic cells, especially
macromolecules, membranes, and organelles
2. Students will understand how these cellular components are used to
generate and utilize energy in cells
3. Students will understand the cellular components underlying mitotic
cell division.
4. Students will apply their knowledge of cell biology to selected
examples of changes orlosses in cell function. These can include
responses to environmental or physiological
changes, or alterations of cell function brought about by mutation.
8.1 WHAT IS A CELL?
Unicellular organisms are capable of (i) independent existence and
(ii) performing the essential functions of life. Anything less than a complete
structure of a cell does not ensure independent living. Hence, cell is the
fundamental structural and functional unit of all living organisms.
Anton Von Leeuwenhoek first saw and described a live cell. Robert
Brown later discovered the nucleus. The invention of the microscope and
its improvement leading to the electron microscope revealed all the
structural details of the cell.
8.2 CELL THEORY
In 1838, Matthias Schleiden, a German botanist, examined a large number
of plants and observed that all plants are composed of different kinds of
cells which form the tissues of the plant. At about the same time, TheodoreSchwann (1839), a British Zoologist, studied different types of animal cells
and reported that cells had a thin outer layer which is today known as the
‘plasma membrane’. He also concluded, based on his studies on plant
tissues, that the presence of cell wall is a unique character of the plant
cells. On the basis of this, Schwann proposed the hypothesis that the bodies
of animals and plants are composed of cells and products of cells.
Schleiden and Schwann together formulated the cell theory. This theory
however, did not explain as to how new cells were formed. Rudolf Virchow
(1855) first explained that cells divided and new cells are formed from
pre-existing cells (Omnis cellula-e cellula). He modified the hypothesis of
Schleiden and Schwann to give the cell theory a final shape. Cell theory
as understood today is:
(i) all living organisms are composed of cells and products of cells.
(ii) all cells arise from pre-existing cells.
8.3 AN OVERVIEW OF CELL
You have earlier observed cells in an onion peel and/or human cheek
cells under the microscope. Let us recollect their structure. The onion cell
which is a typical plant cell, has a distinct cell wall as its outer boundary
and just within it is the cell membrane. The cells of the human cheek
have an outer membrane as the delimiting structure of the cell. Inside
each cell is a dense membrane bound structure called nucleus. This
nucleus contains the chromosomes which in turn contain the genetic
material, DNA. Cells that have membrane bound nuclei are called
eukaryotic whereas cells that lack a membrane bound nucleus are
prokaryotic. In both prokaryotic and eukaryotic cells, a semi-fluid matrix
called cytoplasm occupies the volume of the cell. The cytoplasm is the
main arena of cellular activities in both the plant and animal cells. Various
chemical reactions occur in it to keep the cell in the ‘living state’.
Besides the nucleus, the eukaryotic cells have other membrane bound
distinct structures called organelles like the endoplasmic reticulum (ER),
the golgi complex, lysosomes, mitochondria, microbodies and vacuoles.
The prokaryotic cells lack such membrane bound organelles.
Ribosomes are non-membrane bound organelles found in all cells –
both eukaryotic as well as prokaryotic. Within the cell, ribosomes are
found not only in the cytoplasm but also within the two organelles –
chloroplasts (in plants) and mitochondria and on rough ER.
Animal cells contain another non-membrane bound organelle called
centrosome which helps in cell division.
Cells differ greatly in size, shape and activities (Figure 8.1). For example,
Mycoplasmas, the smallest cells, are only 0.3 µm in length while bacteria
Sampling is a process used in statistical analysis in which a predetermined number of observations are taken from a larger population. The methodology used to sample from a larger population depends on the type of analysis being performed, but it may include simple random sampling or systematic sampling.
CLI
KEY TAKEAWAYS
Certified Public Accountants use sampling during audits to determine the accuracy and completeness of account balances.1
Types of sampling include random sampling, block sampling, judgement sampling, and systematic sampling.
Companies use sampling as a marketing tool to identify the needs and wants of their target market.
