2021 | 1ª Série | Biologia | Aula 33 - Doenças Relacionadas ao Ciclo Celular

Summary

In this lesson, Professor Luciano explores the cell cycle, focusing on mitosis and meiosis, and their relation to genetic disorders. He explains how chromosome alterations, such as numerical and structural changes, can lead to diseases. The lesson also covers the role of telomeres in aging and their significance as biomarkers. Additionally, apoptosis, a programmed cell death process, is discussed in the context of diseases like cancer, Alzheimer's, and Parkinson's, highlighting its importance in maintaining cellular balance. The session underscores how disruptions in the cell cycle and apoptosis contribute to various health conditions.

Takeaways

• 😀 Mitosis is a type of cell division that results in two identical cells with the same chromosome number, essential for growth and cell replacement.
• 😀 Meiosis, unlike mitosis, reduces the chromosome number by half and is responsible for producing gametes (sperm and eggs).
• 😀 Telomeres, located at the ends of chromosomes, protect genetic material and shorten with age, which can be a biomarker for aging and associated diseases.
• 😀 The length of telomeres is associated with the biological age of an individual, and their degradation can lead to premature aging and cell death.
• 😀 Chromosomal alterations can be structural (deletions, duplications, inversions, translocations) or numerical (e.g., trisomy, like Down syndrome).
• 😀 Apoptosis is programmed cell death, a natural process that eliminates damaged or unnecessary cells, and is different from necrosis, which is caused by injury.
• 😀 When DNA is damaged, the cell attempts to repair it. If it cannot be repaired, apoptosis is triggered to prevent the damage from spreading.
• 😀 Cancer results from uncontrolled cell division due to failures in apoptosis or mutations in genes regulating the cell cycle.
• 😀 Diseases like Alzheimer’s and Parkinson’s are linked to excessive apoptosis, where too many cells die, leading to neurodegeneration.
• 😀 Autoimmune diseases such as lupus are related to a failure in apoptosis, where cells that should die continue to survive, causing immune system issues.
• 😀 Chemotherapy can induce apoptosis in cancer cells, halting their uncontrolled reproduction and preventing the spread of tumors.

Q & A

What is the main objective of the lesson described in the transcript?

The main objective of the lesson is to understand the chromosomal alterations that can occur during the cell cycle, especially during mitosis, and to learn about the concept of apoptosis and its relationship to diseases.

What are telomeres and what role do they play in aging?

Telomeres are repetitive sequences of DNA and proteins found at the ends of chromosomes. Their primary function is to prevent the degradation of genetic material and maintain chromosomal stability. As telomeres shorten with age, cells stop reproducing, which is associated with the biological aging process.

What is the difference between mitosis and meiosis?

Mitosis is a process of cell division that results in two identical cells, maintaining the same number of chromosomes. Meiosis, on the other hand, is the process that reduces the chromosome number by half to produce gametes, leading to four non-identical cells with half the original chromosome number.

How are diseases related to the cell cycle?

Diseases related to the cell cycle often arise from errors in the mitotic or meiotic processes, as well as from problems during interphase, leading to chromosomal alterations, such as numerical or structural changes, which can result in conditions like cancer or genetic disorders.

What are numerical chromosomal alterations, and can you give an example?

Numerical chromosomal alterations involve changes in the number of chromosomes, such as having more or fewer chromosomes than normal. An example is trisomy 21, which causes Down syndrome, where there are three copies of chromosome 21 instead of two.

What are structural chromosomal alterations, and how do they affect the organism?

Structural chromosomal alterations include deletions, duplications, inversions, and translocations, which can change the structure of chromosomes without altering their number. These changes can lead to genetic diseases, structural defects, or cancer due to disruptions in gene expression.

What is apoptosis and how is it different from necrosis?

Apoptosis is programmed cell death, a natural process that helps maintain tissue health and homeostasis by removing damaged or unnecessary cells. It is different from necrosis, which is a form of cell death caused by injury or disease, leading to inflammation.

What role does apoptosis play in cancer treatment?

In cancer treatment, apoptosis is triggered to eliminate cancerous cells. Chemotherapy, for example, aims to induce apoptosis in cancer cells, preventing their uncontrolled growth and division.

How do mutations in oncogenes contribute to cancer development?

Mutations in oncogenes lead to the overactivation of genes that promote cell proliferation. These mutations result in uncontrolled cell division, which is a key characteristic of cancer.

What is the connection between apoptotic dysfunction and autoimmune diseases?

In autoimmune diseases, there is often a failure in apoptosis, leading to the survival of cells that should normally be removed. This can result in the immune system attacking the body's own tissues, as seen in conditions like lupus.