Cell division is the process cells go through to divide. There are several types of cell division.
Thousands of cells die daily in our body and thousands of new ones are produced. This happens by the process of cell division, in which a parental cell gives rise to two daughter cells.
The process involves both division of the nucleus (karyokinesis) and division of the cytoplasm (cytokinesis). It can either produce two identical cells or two entirely different cells.
This course covers following:
- Distinguish between normal and cancer cells.
- Understand prokaryotic cell division.
- Understand eukaryotic cell division.
- Distinguish between mitosis and meiosis.
- Explain and identify checkpoints of the cell cycle.
When tissues get injured, the injury site becomes a hotbed of activity. New cells are formed by the process of cell division for repairing worn-out or damaged tissues.
The immune cells become active, and along with the extracellular matrix (ECM), stimulate tissue repair.
Why Do Cells Divide?
Cells divide to replace or repair damaged cells and tissues and to propagate by forming daughter cells.
The extracellular matrix (ECM) is the non-cellular component present within all tissues and organs. It provides essential physical scaffolding for the cellular constituents.
ECM also initiates crucial biochemical and biomechanical reactions that are required for tissue morphogenesis, differentiation, and homeostasis.
Binary Fission
Most prokaryotes or bacteria divide by the process of binary fission. Eukaryotes divide asexually by Mitosis.
Sexually-reproducing eukaryotes use a special form of cell division called meiosis. Meiosis helps cells to propagate the genetic content from one cell to another.
Cancer
The cell cycle is the process by which cells progress and divide to form daughter cells.
In normal cells, the cell cycle is controlled by a complex series of signaling pathways as the cell grows, replicates its DNA and divides. Both positive and negative regulators provide the signals.
Characterictics of a Cancer Cell
During the cell cycle, errors in DNA replication are corrected to avoid the programmed cell death (Apoptosis).
However, sometimes genetic mutations occur and generate cancerous cells. The regulatory process for these cells malfunctions, resulting in uncontrolled cell proliferation.
Cancer is the uncontrolled growth of abnormal cells in the body. Old cells do not die, but instead grow out of control and form new abnormal cells. These extra cells may form a mass of tissue, called a tumor.
The genetic changes affecting three main types of genes, namely proto-oncogenes, tumor-suppressor genes, and DNA repair genes cause cancer.
Table showing differences between Normal and Cancer Cell
| Characteristics | Normal Cell | Cancer Cell |
| Growth | Regulated normal cell growth | Uncontrolled growth and invasive |
| Specialization | Specialized as they mature into different cell types with specific function | Less specialized |
| Apoptosis | Present | Ignores signals that induces apoptosis |
| Interactions | Respond to signals sent by nearby cells | Do not interact with other cells |
| Specialized Cells | May possess differentiated cell structures and there is normal cell markers presentation | Absence of specialized cell features and over-expression of certain markers |
| Adhesiveness | Secrete substances that make them stick together in a group | Float in bloodstream and lymph |
| Growth and Reproduction | Normal growth and reproduction | Fast growth and reproduction before the cells mature |
| Immune System | Immune system removed damaged cells | Escapes immune system or inactivates it by secreting chemicals |
| Angiogenesis | Undergo process of Angiogenesis | Absent |
| Growth Suppressors | Controlled by growth suppressors | Not regulated by growth suppressors |
| Cell Environment | Cell environment is alkaline | Cell environment is acidic |
| Energy Efficiency | Energy efficiency is very high 95% | Energy efficiency is very low 5% |
Types of Cancer Cells
There are five major types of cancer as shown below:
- Carcinoma: cancer arising in the epithelial tissue of the skin or of the lining of the internal organs
- Sarcoma: cancer in bone, muscle, fat, blood vessels, cartilage, or other soft or connective tissues of the body
- Melanoma: cancer that arise in the cells that make the pigment in skin
- Lymphoma: cancer of lymphocytes
- Leukemia: cancer of blood
External References
https://www.britannica.com/science/cell-biology/Cell-division-and-growth
https://www.nature.com/scitable/topicpage/mitosis-and-cell-division-205/
