what is the cell cycle?
The cell cycle, or cell-division cycle, is the series of events that take place in a eukaryotic cell between its formation and the moment it replicates itself. These events can be divided in two main parts:
What are the stages of the cell cycle?
<ul> <li><strong>Growth (G1)</strong>: The cell grows and does its usual job.</li> <li><strong>Copy DNA (S)</strong>: The cell duplicates its DNA.</li> <li><strong>Preparation (G2)</strong>: The cell gets ready for division.</li> <li><strong>Division (M)</strong>: The cell divides into two new cells.</li> </ul> <br>
What are the stages of mitosis? What is the main goal of mitosis?
- Prophase: Chromosomes condense, the nuclear envelope breaks down, and spindle fibers form.
- Metaphase: Chromosomes line up in the middle of the cell.
- Anaphase: Sister chromatids separate and move towards opposite poles of the cell.
- Telophase: Chromosomes de-condense, nuclear envelopes re-form around the separated chromosomes, and spindle fibers disassemble.
- Cytokinesis: The cytoplasm divides, resulting in two daughter cells.
The main goal of mitosis is to ensure that each daughter cell receives an identical set of chromosomes to the parent cell. This process ensures cell growth, tissue repair, and asexual reproduction.
What is Cytokinesis?
cytokinesis which divides the cytoplasm and cell membrane. This results in two identical cells with an equal distribution of organelles and other cellular components.
What is meiosis? What is the main goal of prophase 1 of Meiosis 1?
Meiosis is a special type of cell division for making reproductive cells (sperm and egg). In prophase I of meiosis I, the main goal is to mix up the genes to create genetic variety.
During prophase I:
- Chromosomes condense and become visible.
- Pairs of matching chromosomes swap pieces of DNA, mixing up their genes.
- This mixing, called crossing over, creates new combinations of genes, making each reproductive cell unique.
- It sets the stage for the rest of meiosis to create cells with half the number of chromosomes.
what type of cells does meiosis create?
Meiosis creates reproductive cells called gametes. In humans and many other organisms, gametes are sperm cells in males and egg cells (ova) in females
Distinguish between meiosis and mitosis
<ul> <li>Purpose: <ul> <li><strong>Meiosis</strong>: Creates reproductive cells (gametes) for sexual reproduction, with half the number of chromosomes as the parent cell.</li> <li><strong>Mitosis</strong>: Produces identical copies of cells for growth, repair, and asexual reproduction, maintaining the same number of chromosomes as the parent cell.</li> </ul></li> <li>Number of Divisions: <ul> <li><strong>Meiosis</strong>: Two rounds of division (meiosis I and meiosis II), resulting in four daughter cells.</li> <li><strong>Mitosis</strong>: One round of division, resulting in two daughter cells.</li> </ul></li> </ul> <br>
How does the cell cycle of cancer differ from normal cells?
- Uncontrolled Growth: Cancer cells keep dividing uncontrollably, unlike normal cells that stop when they should.
- Defective Checkpoints: Normal cells have "stop signs" to ensure safe division. Cancer cells ignore these signs and keep dividing, even with problems.
- Abnormal Chromosomes: Cancer cells often have the wrong number of chromosomes, which can make them unstable and prone to more mutations.
- Immortality: Cancer cells can live forever by avoiding natural cell death and continuously dividing.
- No Contact Inhibition: Normal cells stop dividing when they touch each other. Cancer cells ignore this and keep growing, even in crowded spaces.