38 Questions
What are the two main components of a spindle fiber?
Kinetochore and nonkinetochore microtubules
What is the function of the kinetochore?
To facilitate the separation of the sister chromatids
During which phase of mitosis do the chromosomes become visible?
Prophase
What is the purpose of the spindle fibers?
To separate the sister chromatids
What happens to the nuclear envelope during prophase?
It starts to fragment
During which phase of mitosis do the sister chromatids separate?
Anaphase
What is the function of the aster?
To organize the microtubules
What happens after mitosis?
Cytokinesis, the separation of the cytoplasm and its contents
What is the result of the replication process in a coli cell?
Two daughter cells result.
What is the term for the development of cancerous cells with specific characteristics?
Carcinogenesis
What is the main characteristic of benign tumors?
They are encapsulated and do not invade neighboring tissue.
What is the purpose of the contractile ring in cytokinesis?
To separate the cytoplasm between the two daughter cells
What is the purpose of angiogenesis in cancer cells?
To form new blood vessels to feed nutrients and oxygen to a cancerous tumor
What is the result of metastasis in cancer cells?
The cancer cells invade neighboring tissues and spread through the body
What is the role of the Golgi apparatus in plant cell cytokinesis?
To produce vesicles that fuse to form the cell plate
What is the function of the G1 checkpoint?
To commit the cell to division
What is the purpose of cancer treatment?
To remove cancer cells or interfere with their ability to divide
What is the term for cancer of the blood?
Leukemia
What is the role of p53 protein?
To stop the cell cycle at the G1 checkpoint if DNA is damaged
What is the function of the RB protein?
To prevent excessive cell growth by inhibiting cell cycle progression
What is the characteristic of cancer cells in terms of their nuclei?
They have abnormally large nuclei and/or nuclei with an abnormal number of chromosomes
What is the purpose of the G2 checkpoint?
To ensure DNA replication is completed
What is the role of the M checkpoint?
To ensure chromosomes are distributed accurately to the daughter cells
What happens if DNA damage is not corrected during the G1 checkpoint?
The cell cycle is stopped, and apoptosis is initiated
What is the cell cycle?
The period of time from the production of a daughter cell to the cellular reproduction of that cell to produce two new daughter cells
What is the longest stage of the cell cycle?
Interphase
What happens during the G1 phase?
The cell grows and doubles the number of organelles
What is the purpose of the S phase?
To create a duplicate DNA strand
What happens during the G2 phase?
The cell synthesizes proteins needed for cell division
What is the result of mitosis?
The production of genetically identical daughter cells
What is the role of spindle fibers in mitosis?
To separate sister chromatids
What is the result of cytokinesis?
The division of the cytoplasm and its contents
What is the purpose of radiation therapy in cancer treatment?
To kill cancerous cells by damaging their DNA
Which of the following is NOT a protective behavior against cancer?
Cigarette smoking
What is the purpose of hormonal therapy in cancer treatment?
To interrupt the signals that contribute to cancer cell division
What is the effect of excessive alcohol consumption on cancer risk?
It increases the risk of certain types of cancer
What is the purpose of chemotherapy in cancer treatment?
To kill cancer cells that have metastasized
What is a recommended dietary guideline for reducing cancer risk?
Increased consumption of vegetables from the cabbage family
Study Notes
The Cell Cycle
- The cell cycle spans the period of time from the production of a daughter cell to the cellular reproduction of that cell to produce two new daughter cells.
- The cell cycle consists of two main stages: Mitotic (M) phase and Interphase.
Interphase
- A cell spends most of its existence in Interphase, where it performs normal activities and functions.
- Interphase has three stages: G1, S, and G2.
- During G1, the cell grows and doubles its organelles and resources in preparation for DNA replication.
- During S, DNA replication begins to create a duplicate DNA strand, resulting in sister chromatids.
- During G2, the cell synthesizes proteins needed for cell division.
Mitotic (M) Phase
- The M phase consists of Mitosis and Cytokinesis.
- Mitosis is the division of nuclear material (DNA), producing two genetically identical daughter chromosomes.
- Cytokinesis is the division of the cytoplasm and its contents, resulting in two daughter cells with the same number of chromosomes as the original cell.
Mitosis and Cytokinesis
- The separation of sister chromatids during mitosis occurs in four phases: Prophase, Metaphase, Anaphase, and Telophase.
- The spindle fibers, organized by the centrosome, attach to each duplicated chromosome at the kinetochore, facilitating the separation of sister chromatids.
- In animal cells, centrosomes consist of two centrioles and an array of microtubules called an aster.
- Cytokinesis in plant cells occurs by forming a new cell wall between the daughter cells, with the Golgi apparatus producing vesicles that fuse to form the cell plate.
The Cell Cycle Control System
- The cell cycle is tightly regulated to ensure it is completed correctly.
- The control system has checkpoints that control the progression of the cell cycle, ensuring that the stages of interphase occur sequentially in the correct order.
- The G1 checkpoint is important, as passing this point commits the cell to division.
- Proteins like p53 and RB protein regulate the cell cycle, stopping it at the G1 checkpoint if DNA is damaged and initiating DNA repair.
Cancer and the Cell Cycle
- Cancer is a disease of the cell cycle, characterized by uncontrolled cell division.
- Cancer cells lack differentiation, have abnormally large nuclei, and/or nuclei with an abnormal number of chromosomes.
- Cancer cells form a mass of dividing cells called a tumor, which can undergo metastasis.
- Cancer treatments include surgery, radiation therapy, chemotherapy, and hormonal therapy.
Prevention of Cancer
- Evidence suggests that certain lifestyle changes can reduce the risk of certain types of cancer.
- Adopting protective behaviors, such as avoiding potentially harmful activities, and following a protective diet can help reduce the risk of cancer.
Learn about the process of cytokinesis in plant and animal cells, including the formation of contractile rings and cell plates.
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