Introduction
The senescent phase is the period after the reproductive phase, when a cell loses its ability to reproduce. Here, the cell may age and stops dividing, but it does not die. Termed as cell ageing, in this process such cells stay within the body and may cause various illnesses.
Over time, a significant amount of such cells may accumulate in tissues, remain active and release harmful substances. These substances may cause inflammation and damage to the healthy cells near them. They can even give birth to fatal diseases like cancer.
Definition of Senescence
In simpler words, senescence is biological ageing. In biology, it refers to the state where cells can no longer divide; however, they remain active and alive. Moreover, it is inevitable in every multicellular organism, be it a human, or animal or a plant.
Therefore, it pertains to the biological ageing of every living thing and involves a gradual decline of morphological features and for the purpose of a cell or the whole organism.
Furthermore, the senescent phase entails detriments and benefits for organisms in which such cells live. Even though cellular senescence was first associated with ageing and tumour suppression, recent researches show more results. Current research has found that this phase also plays a part in tissue repair, but promotes cancer.
Moreover, several features distinguish these cells from others. Apart from their inability to divide, they are also bigger than healthy cells. Additionally, they secrete specific molecules, which healthy cells do not.
After reading the senescence definition, one might what causes cell senescence? Read on to know more.
Reasons behind Cellular Senescence
There are several reasons behind cellular senescence, some of the primary ones are discussed below –
Telomere Erosion
It is one of the most common reasons for cellular senescence. Telomeres are a sequence of DNA, which is found at the end of each chromosome. It consists of DNA structures of repeated nucleotides.
For instance, repeated nucleotides in human telomeres are TTAGGG. This repetition saves chromosomes from losing crucial information while replicating, and from blending with nearest ones.
Moreover, with each replication, the telomeres lose a small part of its DNA as the enzymes responsible for this cannot reach the end of chromosomes. Therefore, chromosomes are shortened after each replication, and after a period, they miss crucial genetic information.
Moreover, the cell now goes through DNA damage response (DDR). Thus, they cannot divide anymore and are considered senescent.
Other Variation of DNA Damage
Along with telomere erosion, other types of DNA damage can also cause cellular senescence. One of the most common causes here is DNA double-strand breaking. It also brings DDR and subsequently results in the senescent phase of a cell.
Other Reasons
Apart from any DNA damage, senescence inducers, which act independently of DNA damage, can cause this situation. The reasons includes –
Presence of signalling molecules, which modifies cellular functions like cellular stress.
Abnormal expression of several proteins like tumour suppressors.
Changes in DNA associated proteins like chromatin.
Effects of Senescent Phase
The effects of this phase are attributed to the age of individuals. In the case of younger people, it controls the growth of a tumour; it induces the same in the case of older people as well.
Moreover, the effects of cellular senescence include secreting molecules that help in tissue repair.
Senescence in Plants
Similar to human beings, senescence in plants is the second last stage of their development. Hormones like ethylene and abscisic acids are some of the typical hormones, which promotes senescence.
Moreover, senescence is essential for the fitness and survival of plants.
The senescent phase is a vital process in the life-cycle of every living organism. Additionally, students can access study material and join our live classes via the official Vedantu app and website to learn more about Biology.
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Relevance of Senescence
Senescence is a biological process in which any cell stops dividing. However, it does not die. The cells that have completely aged stop dividing in the body and then accumulate in the form of tissues. They need to be checked properly so that the harmful substances that they release do not harm the body. They accumulate as a build-up of tissues and may cause diseases like cancer in humans. They need to be studied properly by all students who need to perform well in their exams. All those students who wish to take up Biology in their later years need to know about Senescence in depth.
How to Study for Senescence before an Exam
Read up Senescence on Vedantu
Go through the entire page and then write all the important concepts down in your own words
Highlight all the key areas
Use drawings to understand the topics and subtopics well
Re-read those sections that have not been properly understood
Solve questions and solve mock papers on your own
Revise from everything prior to an exam
FAQs on Senescence
1. How to define senescence?
To define senescence, it can be said that it is the penultimate step of any cell’s growth. At this point, cells stop dividing, but they do not die. This process has both positive and negative impact on human health.
2. What is the meaning of senescence in plants?
Senescence in plants is the same as in human beings. However, this process is essential for plants to survive. A visible example of this situation in plants is when they shed leaves during autumn.
3. What is the adverse effect of senescence in human?
The adverse effect of senescence in human is that it can promote cancer.
4. What is biological ageing?
Biological ageing is also known as Senescence. Here, the cells of the body stop dividing but remain active. They need to be screened from time to time to make sure that they do not cause any major disease in the body.
5. What are the reasons behind Senescence?
All the reasons that cause senescence have been explained in Senescence that is on Vedantu.
This page has vital information on the topic and contains all the relevant portions. The explanations behind every concept have been listed in detail here. Knowing the causes for something helps the students understand any process in the right manner. This then sees to it that they perform well in all exams. They can download this in an offline mode in the form of a PDF and then read from the same.
6. How can students make notes on the effects of the senescent phase?
Students need to understand what senescence is and then read up about it online. They can refer to Senescence on Vedantu and find out more. This page has explained the senescent phase and all the other phases that the students need to be aware of. It is great in terms of understanding the concepts and can be used by all students for the purpose of making notes. Everything here has been listed as per the course structure and the Board’s guidelines. Nothing that is extra has been included on this page.
7. Does senescence also take place in plants?
Yes, Senescence is a phenomenon that has to do with plants as well. It is necessary for their fitness and overall survival. Students of Biology who are really interested in the topic can check out Senescence on Vedantu’s online tutoring platform. This phenomenon needs to be understood well so that the students answer all questions that come from the topic. This page is an ideal guidebook for them to go through so that they understand all concepts. It is a boon for all those who need to study Senescence right before an exam as it contains the key pointers.
8. Do cells ever stop dividing?
As the body ages, cells stop dividing but remain active. They can accumulate in the form of tissues and cause growths that can either be benign or malignant. This process is known as Senescence and needs to be studied by all students who have taken up Biology. It is an important concept that needs to be known by them. All cells at some point or the other stop dividing as they reach their maturity. This process has been elaborated upon in Senescence that’s on Vedantu’s online tutoring platform. It is a vital chapter to be studied from.
