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Questions and Answers
Which proteins are considered external regulators that influence the cell cycle?
Which proteins are considered external regulators that influence the cell cycle?
What is the primary function of cyclins in the cell cycle?
What is the primary function of cyclins in the cell cycle?
What are the characteristics of malignant tumors?
What are the characteristics of malignant tumors?
Which of the following statements best describes proto-oncogenes?
Which of the following statements best describes proto-oncogenes?
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What term describes the phenomenon where cells slow their division as cellular density increases?
What term describes the phenomenon where cells slow their division as cellular density increases?
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What is the role of the p53 gene in relation to cancer?
What is the role of the p53 gene in relation to cancer?
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How do cancer cells differ from normal cells in terms of growth controls?
How do cancer cells differ from normal cells in terms of growth controls?
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What is metastasis in the context of cancer?
What is metastasis in the context of cancer?
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What is the primary goal of mitosis and cell division?
What is the primary goal of mitosis and cell division?
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What happens to the surface area-to-volume (SA:V) ratio as a cell grows larger?
What happens to the surface area-to-volume (SA:V) ratio as a cell grows larger?
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What occurs during the G2 Phase of interphase?
What occurs during the G2 Phase of interphase?
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During which phase of mitosis do chromosomes align at the cell's equator?
During which phase of mitosis do chromosomes align at the cell's equator?
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What is formed during cytokinesis in plant cells?
What is formed during cytokinesis in plant cells?
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How many identical sister chromatids are formed after the S phase if a cell originally has 46 chromosomes?
How many identical sister chromatids are formed after the S phase if a cell originally has 46 chromosomes?
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In prokaryotes, how do they replicate their single circular chromosome?
In prokaryotes, how do they replicate their single circular chromosome?
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What is the function of the centromere during mitosis?
What is the function of the centromere during mitosis?
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Study Notes
Cell Growth and Division
- Cells divide for growth, repair, and development.
- Smaller cells have a higher surface area to volume ratio, which is more efficient for nutrient uptake and waste removal.
- Large cells struggle with material exchange and DNA access, thus requiring division.
- Cell division solves the problems of insufficient material exchange and DNA overload.
Cell Cycle
- The cell cycle is a series of events that cells undergo to grow and divide.
- It's divided into interphase and M phase.
- Interphase is the period between cell divisions and consists of G1, S, and G2 phases.
- G1 (Gap 1) phase: Growth, protein and organelle synthesis.
- S (Synthesis) phase: DNA replication, replication of key proteins like centromeres.
- G2 (Gap 2) phase: Organelle and molecules needed for cell division are created.
- M phase: Mitosis and cell division.
Mitosis
- Mitosis is the division of the nucleus.
- Four main phases:
- Prophase: Chromatin condenses into chromosomes, nuclear envelope and nucleolus break down, spindle fibers form.
- Metaphase: Chromosomes align at the cell's equator, connected to spindle fibers at the centromere.
- Anaphase: Sister chromatids separate and move to opposite poles.
- Telophase: Chromosomes decondense, nuclear membranes reform, nucleoli reappear.
- Cytokinesis follows mitosis, dividing the cytoplasm and forming two daughter cells.
- Plant cells form a cell plate, creating a new cell wall between the two cells.
Cell Cycle Regulation
- Internal regulators (e.g., cyclins, CDKs) and external regulators (e.g., growth factors) control the cell cycle.
- Cyclins activate CDKs (cyclin-dependent kinases), enzymes that control cell cycle progression.
- Growth factors are external signals telling cells when to divide.
- Density-dependent inhibition: Cells stop dividing when they touch other cells.
- Anchorage dependence: Cells must be attached to a substratum to divide.
Cancer
- Cancer is uncontrolled cell growth and division.
- Tumors are masses of cancer cells. Benign tumors do not spread, malignant tumors do.
- Cancer is caused by various factors, such as carcinogens, radiation, viral infections, and genetics.
- A common factor in cancer is the malfunctioning control of the cell cycle.
- Cancer cells are not subject to density-dependent inhibition or anchorage dependence.
- Proto-oncogenes (normal genes controlling growth) can mutate into oncogenes, leading to uncontrolled growth.
- Tumor suppressor genes (e.g., p53) prevent uncontrolled cell division by detecting and repairing damaged DNA.
Cancer Treatment
- Cancer treatments may target the affected area (surgery, radiation) or affect overall cells (hormone therapy, chemotherapy, targeted therapy/immunotherapy).
Chromosome Structure and Replication
- Before entering the cell cycle, chromosomes are duplicated.
- The duplicated chromosomes are called sister chromatids.
- The centromere holds the sister chromatids together.
- This means that after replication, the number of chromosomes doesn't change, but the number of chromatids doubles.
- Prokaryotes replicate their single circular chromosome through binary fission, which is distinct from mitosis.
Cell Size and Ratio
- SA:V (surface area to volume ratio) decreases as a cell increases in size.
- This affects how efficient cells are at exchanging materials with their surroundings.
- Small cells are more efficient at carrying out these exchange functions.
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Description
Test your knowledge on cell growth, division, and the cell cycle. This quiz covers the phases of the cell cycle, mitosis, and the reasons cells divide for growth and repair. Perfect for students studying biology concepts related to cellular processes!
