Education Journalist | Study Abroad Lead
Senescence is an important and the most significant process which is usually seen in the organisms who attain an older age. In fact, aging itself is associated with senescence. It is a procedure that is seen in a few cells of an organism or in the organisms as a whole. Senescence is mainly seen in the context of affecting the functional competence of the organisms. However, it also has multiple positive impacts on an organism. In this article, we will discuss the procedure of senescence, its causes, effects, and telomere erosion.
Key Terms: Telomere, Cytokine, Nucleotides, Organisms, Senescence, Functioning, Cells, Aging, Tumor Suppression, Senescent Cell, SASP, DNA
What is Senescence?
[Click Here for Sample Questions]
The growth and development of all living organisms are always associated with the proper functioning of the internal organs of its body. Simultaneously, this proper functioning is also based on the various types of chemical procedures which take place in the body of an animal or plant. However, on the contrary, the process of senescence is mainly known for creating hindrances to the niche of the cells of a body.
Senescence
Senescence refers to a procedure in which a cell or a group of cells stops functioning, although, the cells remain active or alive inside one’s body but do not divide anymore. Under this process, the cells stop reproducing, the life cycle of the cells remains inactive, causing aging in the body of an organism. Researchers have found that senescence is mainly associated with tumor suppression, aging and it also, sometimes, causes cancer. Therefore, the decline in the functional ability of a cell or the group of cells either heterogeneously or homogeneously in a body is the main characteristic of senescence.
| Relevant Concepts | |
|---|---|
| Gene Regulation | Genetics |
| Genetic Disorders | Genetic Drift |
Characteristics of Senescent cell
[Click Here for Sample Questions]
The senescent cell is one that undergoes the process of senescence, it may be a single cell in a body or a group of cells, or all the cells. Some of its basic characteristics are as mentioned below.
- First of all, a senescent cell is usually known for its larger size as it stops further division.
- This type of cell can be extremely detrimental to the health of an organism as it is associated with the secretion of harmful substances or hormones.
- In the normal condition, as soon as a cell reaches its age, it dies and a new cell is reproduced, however, in senescence, no cell dies, rather, it remains alive and also generates the potential of attracting the other surrounding cells into senescence, hindering the overall development.
- After reaching a particular age, it becomes difficult for the body to reduce or eliminate the senescent cell, thus they are known for getting accumulated in a body and further destroying the tissues.
- These cells are associated with the formation of SASP, that is, senescent-associated secretory phenotype. It is formed through the chemicals like cytokine, chemokine, and matrix proteases which are released by the senescent cells.
- This SASP causes detrimental impacts such as cancer, aging, etc.
- It has been found that even if the 30% of these senescent cells are eliminated from the body, the rate of aging is decreased to a greater level.
Senescent Cell
Read More: Chromosomal Theory of Inheritance
Causes of Senescence
[Click Here for Sample Questions]
Some of the causes of senescence are as follows.
-
Telomere Erosion
It is one of the most common and the major causes of senescence. Telomere are referred to as the sequence of DNA of nucleotides which are mainly held at the end of each chromosome. These nucleotides are placed in repetition, like, TTAGGG, which is found in the human telomere. In turn, these repetitions basically provide protection to the chromosomes from further fusion with another set of chromosomes or from losing any significant information during replication.
However, during the process of replication, the enzymes which are responsible for the same remain incompetent to reach the end of the chromosome, thus, causing the telomeres to lose a small part of DNA at every step for making the duplication of DNA an easy process. But at the same time, this also causes shortening of the chromosomes until they reach a substantial point of losing the telomeres which further leads to the loosing of important genetic information. This is also a point where the cell finally enters the senescent phase causing the DNA Damage Response (DDR). Further, a greater number of cells undergo senescence with the increasing age.
-
Other Kinds of DNA Damage
?Damage to the DNA of a cell is caused by various other factors such as breaking of the double-stranded DNA, protein errors, or the cells also entering this phase in the presence of mitogenic signals. Thus, the damage to DNA by any means has the potential to make the cells senescent.
-
Other Factors
Irradiation, cell culture, oncogene activation, excessive mitochondrial ROS are some of the other factors which lead to senescence.
Senescence in Plants
[Click Here for Sample Questions]
Senescence is known to have impacted the plants multiple times. Similar to that of other organisms, it also affects the functions and capabilities of the plants. The characteristics of plants to grow effectively under light are inhibited by senescence. The cells are hugely impacted which in turn causes aging in leaves and stems of the plants preventing their usual growth.
Read More: Genetically Modified Organisms (GMOs)
Effects of Senescence
[Click Here for Sample Questions]
The effects of senescence are as follows:
- One of the major impacts of senescence is aging, it accelerates the rate of aging in humans or animals or even in plants.
- However, at the same time, senescence is associated with tumor growth.
- One of its major peculiarities is that it helps in combating the tumor and helps in its suppression in people of younger age.
- Senescent cells are also known for secreting the hormones which help in the healing of wounds and tissue repair or contribute to strengthening the immune system, however, at the same time, some of the hormones are extremely detrimental to human health.
- The adverse impact of senescence is seen in terms of its contribution to the aging factor and preventing the functional capabilities of the cells.
Things to Remember
- Senescence is also known to occur in the plants before their death. Programmed Cell Death is a unique concept that is associated with senescence in plants.
- Senescence in plants affects their functional ability and leads to similar impacts in humans or animals.
- Overall senescence, top senescence, deciduous senescence, and progressive senescence are the main types of senescence that take place in the plants.
- Post reproduction, a cell may lose its ability to carry on the procedure of reproduction and stop dividing, thus leading to a senescent phase.
- In senescence, the cells never die, however, their functional specialization is reduced to a maximum level.
- The process of senescent is also known for the phase of aging in which cells stop working but continuously remain inside the body and become the source of multiple illnesses.
- These unproductive cells, sometimes, also release harmful fluid or substances which cause inflammation in surrounding healthier cells.
- Senescence can occur in every organism, be it a human, animal, or plant, causing damage to their health.
Sample Questions
Ques. Explain senescence in plants. (2 Marks)
Ans. In general, senescence refers to a procedure in which a cell of an organism or the entire organism as a whole experiences backdrop in their functional specialization. Similarly, senescence is also known to affect plants of all kinds. However, the types of senescence in plants may vary depending upon their nature, such as the top senescence, deciduous senescence, progressive senescence, and overall senescence. Like humans and animals, plants also face hindrances in terms of their growth and development under senescence.
Ques. How do we identify a senescent cell? Explain in terms of its characteristics. (3 Marks)
Ans. The senescent cell is a significant testimony of the occurrence of the entire procedure of senescence. This cell can be understood as the one which undergoes the process of senescence. However, it may be a single cell in a body or a group of cells, or all the cells which are affected by senescence. One of the major characteristics of the senescent cell is its larger size as it stops further division.
This in turn makes the senescent cells an extremely detrimental one for the health of an organism. These cells also possess the features of secreting multiple harmful substances or hormones. Under the process of senescence, no cell dies, rather, it remains alive and also generates the potential of attracting the other surrounding cells into its senescent nature, hindering the overall development.
Ques. What is the significance of senescence? Illustrate its impacts. (3 Marks)
Ans. Senescence is an extremely significant process and its affects the lives of plants, humans, and animals. For instance, one of its major peculiarities of senescence is that it effectively combats tumor and suppresses it forever, however, mainly in the younger population. Although, on the other hand, senescence is also associated with tumor growth in the oldies.
Another major impact of senescence is deeply entrenched in its main characteristic of accelerating the process of aging in humans, animals, or even in plants. It restricts the actual function of the cells and prevents the regrowth of the new cells, making the bodies deficient in the required mechanisms and functions. However, senescent cells are also known for secreting hormones which remain useful in healing wounds and repairing the tissues.
Ques. How is the senescent cell detrimental to the surrounding cells or the whole of human health? (3 Marks)
Ans. Some of the ways in which senescence becomes detrimental to human health are mentioned below.
- One of the major impacts of senescence that is detrimental to human health is aging, it accelerates the rate of aging in humans or animals or even in plants.
- Another adverse impact of senescence could be seen in its association with tumor growth in the old ones.
- Senescent cells are also seen in relation to the formation of SASP, that is, a senescent-associated secretory phenotype that is formed through multiple types of chemicals like cytokine, chemokine, and matrix proteases which are in turn released by the senescent cells only.
- This SASP is known to cause multiple detrimental impacts such as cancer, aging, etc.
Ques. Discuss in brief the telomere erosion. (4 Marks)
Ans. Telomere erosion is known to be one of the most common and major causes of senescence. Telomere erosion is associated with the DNA Damage Response (DDR) which is caused when the cell enters the senescent phase. In simple words, telomere refers to the sequence of DNA of nucleotides that are located at the end of each chromosome. These nucleotides are placed in repetition, like, TTAGGG. The purpose of these repetitions is mainly to grant the required protection to the chromosomes against further fusion with another set of chromosomes or against losing any significant information during replication.
However, during the process of replication, the enzymes which are responsible for the same remain incompetent to reach the end of the chromosome, leading the telomeres to lose a small part of DNA at every step which causes shortening of the chromosomes until they reach a substantial point of losing the telomeres which also further leads to the loosing of the important genetic information. Thus, making the cells enter the senescent phase through telomere erosion.
Ques. What is senescence? Explain briefly. (2 Marks)
Ans. Senescence refers to a procedure in which the cells inside one’s body remain active or alive but do not divide anymore and further stop functioning. Under this process, the cells stop reproducing, the life cycle of the cells remains inactive, causing aging in the body of an organism. Therefore, the decline in the functional ability of a cell or the group of cells in a body is the main testimony of senescence.
Ques. Briefly discuss the phase of senescence. (2 Marks)
Ans. The senescent phase mainly takes place after the reproductive phase in the entire life cycle. Since, it has been known that post - reproduction, a cell may lose its ability to carry on the procedure of reproduction, therefore, it stops dividing and further leads to a senescent phase. In senescence, the cells never die, however, their functional specialization is reduced to a maximum level. The process of senescent is also known for the phase of aging in which cells stop working but continuously remain inside the body and become the source of multiple illnesses.
Check-Out:
Comments