1.6 Cell division Flashcards
What are the three main stages of the cell cycle?
- Interphase, 2. Mitosis, 3. Cytokinesis.
What is the role of cyclins in the cell cycle?
Cyclins regulate the cell cycle by controlling the progression of cells through it, activating cyclin-dependent kinases (CDKs).
During which phase does DNA replication occur in the cell cycle?
DNA replication occurs during the S phase of Interphase.
What are the four phases of mitosis?
- Prophase, 2. Metaphase, 3. Anaphase, 4. Telophase.
How does cytokinesis differ between animal and plant cells?
In animal cells, a cleavage furrow forms to divide the cell. In plant cells, a cell plate forms, eventually becoming the cell wall.
Define benign and malignant tumors.
A benign tumor is non-cancerous and localized, whereas a malignant tumor is cancerous, can spread to other parts of the body, and may recur after removal.
What is the mitotic index and how is it calculated?
The mitotic index is the ratio of cells in mitosis to the total number of cells, indicating the cell division rate. Calculated as P+M+A+T/Totalcells
Describe the link between smoking and cancer.
Smoking is linked to lung cancer and other types of cancers due to the mutagenic compounds in cigarette smoke that can cause cellular DNA damage.
What is tumorigenesis?
Tumorigenesis is the process of tumor formation, involving uncontrolled cell division due to genetic mutations.
How do mutagens, oncogenes, and metastasis contribute to cancer?
Mutagens cause DNA mutations, oncogenes are mutated genes that drive tumor growth, and metastasis is the spread of cancer from the primary site to other parts of the body.
What significant processes occur in the G1 and G2 phases of Interphase?
In the G1 phase, the cell grows and performs normal functions, with rapid protein synthesis preparing it for S phase. In the G2 phase, protein synthesis occurs to produce proteins needed for cell division, such as those that make up the mitotic spindle.
How do cyclins and CDKs regulate the cell cycle?
Cyclins regulate the cell cycle by activating cyclin-dependent kinases (CDKs). The activated CDKs then phosphorylate other proteins in the cell, triggering them to carry out specific tasks related to cell cycle progression, such as DNA replication and cell division.
How do chromosomes condense by supercoiling during mitosis?
During mitosis, chromatin fibers coil and fold in a process known as supercoiling, condensing into visible chromosomes. This condensation allows the chromosomes to be more easily separated and distributed to daughter nuclei.
How can you identify the phases of mitosis in cells viewed with a microscope or in a micrograph?
Identify prophase by condensed chromosomes and dissolving nuclear envelope, metaphase by chromosomes aligned at the cell’s equator, anaphase by separated sister chromatids moving to opposite poles, and telophase by reformation of the nuclear membranes around separated chromatids.
How is the mitotic index calculated and what does it indicate?
The mitotic index is calculated as Number of cells inmitosis/Total number of cells. It indicates the proportion of cells undergoing division at a given time and is used to assess cell proliferation rates, especially in cancerous tissues.
