Q1. What is the difference between interphase and M-phase, and which one lasts longer?

Background

Topic: Cell Cycle Phases

This question tests your understanding of the two main parts of the cell cycle: interphase (when the cell grows and prepares for division) and M-phase (when the cell actually divides).

Key Terms:

• Interphase: The period of cell growth and DNA replication.

• M-phase (Mitotic phase): The period of cell division, including mitosis and cytokinesis.

Step-by-Step Guidance

1. Recall that the cell cycle is divided into interphase and M-phase.

2. Interphase includes G1, S, and G2 stages, where the cell grows, replicates DNA, and prepares for division.

3. M-phase includes mitosis (division of the nucleus) and cytokinesis (division of the cytoplasm).

4. Think about which phase takes longer: Is the cell spending more time growing and preparing, or actually dividing?

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Q2. Complete the following table outlining the steps of the cell cycle

Background

Topic: Cell Cycle Stages

This question tests your ability to identify and summarize the events that occur in each phase of the cell cycle.

Key Terms:

• G1: Cell growth, duplication of cellular components, checkpoint.

• S: DNA synthesis/replication.

• G2: Cell growth, preparation for mitosis, checkpoint.

• M-phase: Mitosis and cytokinesis.

Step-by-Step Guidance

1. Review the main events that happen in each phase: G1, S, G2, and M-phase.

2. For G1, focus on cell growth and the checkpoint that determines if the cell will continue dividing.

3. For S, remember that DNA is replicated and centrosomes are duplicated.

4. For G2, the cell grows further and checks for DNA damage before entering M-phase.

5. For M-phase, recall the steps of mitosis: prophase, metaphase, anaphase, telophase, and cytokinesis.

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Q3. What is the difference between diploid and haploid cells? In humans, what kinds of cells are diploid, and what kinds are haploid?

Background

Topic: Chromosome Number and Cell Types

This question tests your understanding of chromosome number in different cell types and the distinction between somatic and gamete cells.

Key Terms:

• Diploid (): Two sets of chromosomes.

• Haploid (): One set of chromosomes.

• Somatic cells: Body cells (non-sex cells).

• Gametes: Sex cells (sperm and egg).

Step-by-Step Guidance

1. Recall the definitions of diploid and haploid.

2. Think about which cells in humans are somatic and which are gametes.

3. Consider the chromosome number in each type: somatic cells have two sets, gametes have one set.

4. Use the notation for diploid and for haploid.

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Q4. Define somatic cells, and are they diploid or haploid?

Background

Topic: Cell Types

This question tests your understanding of the definition and chromosome number of somatic cells.

Key Terms:

• Somatic cells: Non-sex cells, make up most of the body.

• Diploid (): Two sets of chromosomes.

Step-by-Step Guidance

1. Recall what somatic cells are (all cells except sperm and egg).

2. Think about their chromosome number: do they have one or two sets?

3. Use the term diploid () to describe their chromosome number.

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Q5. Identify and describe the components that move chromosomes during M-phase: centrosome, centriole, microtubules.

Background

Topic: Mitosis Machinery

This question tests your knowledge of the structures involved in chromosome movement during cell division.

Key Terms:

• Centrosome: Organizes spindle fibers.

• Centriole: Cylindrical structures within the centrosome.

• Microtubules: Protein filaments that form the mitotic spindle.

Step-by-Step Guidance

1. Recall the role of the centrosome in organizing the spindle apparatus.

2. Think about the structure of centrioles and their location within the centrosome.

3. Consider how microtubules form the spindle and move chromosomes.

4. Describe how motor proteins interact with microtubules to move chromosomes.

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Q6. Compare and contrast plant and animal cytokinesis, and describe how the cleavage furrow and cell plate play into these processes.

Background

Topic: Cytokinesis in Plants vs. Animals

This question tests your understanding of how cell division differs between plant and animal cells.

Key Terms:

• Cytokinesis: Division of the cytoplasm.

• Cleavage furrow: Structure in animal cells during cytokinesis.

• Cell plate: Structure in plant cells during cytokinesis.

Step-by-Step Guidance

1. Recall that animal cells use a cleavage furrow to divide, while plant cells use a cell plate.

2. Think about the presence or absence of centrosomes, centrioles, and microtubules in plant vs. animal cells.

3. Describe how the cell plate forms in plant cells and how the cleavage furrow forms in animal cells.

4. Compare the end result: two daughter cells in both cases, but the mechanism differs.

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Q7. What do checkpoints do, and how do they do this job? (Discuss cyclin/cdk’s in your answer)

Background

Topic: Cell Cycle Regulation

This question tests your understanding of cell cycle checkpoints and the role of cyclins and cyclin-dependent kinases (CDKs).

Key Terms:

• Checkpoint: Control point in the cell cycle.

• Cyclin: Protein that regulates the cell cycle.

• CDK: Cyclin-dependent kinase, enzyme that partners with cyclin.

• MPF: Mitosis-promoting factor, complex of cyclin and CDK.

Step-by-Step Guidance

1. Recall the three main checkpoints: G1, G2, and M.

2. Think about how cyclins and CDKs interact to control progression through these checkpoints.

3. Describe how cyclin levels fluctuate and bind to CDKs to form MPF.

4. Consider what happens if the checkpoint is not passed (cell cycle stops or cell dies).

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Q8. What is a way that cells speed up or slow down the cell cycle?

Background

Topic: Cell Cycle Regulation

This question tests your understanding of genetic factors that regulate cell division.

Key Terms:

• Proto-oncogenes: Promote cell division.

• Tumor-suppressor genes: Inhibit cell division.

• p53 gene: Tumor-suppressor gene.

Step-by-Step Guidance

1. Recall that proto-oncogenes (like cyclins and CDKs) promote cell division.

2. Think about how tumor-suppressor genes (like p53) inhibit cell division when DNA is damaged.

3. Consider how mutations in these genes can affect the speed of the cell cycle.

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Q9. What cellular signals control the cell cycle (cell division of a cell)?

Background

Topic: Cell Cycle Regulation

This question tests your understanding of external and internal signals that regulate cell division.

Key Terms:

• Nutrients: Availability affects cell division.

• Growth factors: Proteins that stimulate cell division.

• Density-dependent inhibition: Cells stop dividing when crowded.

• Anchorage dependence: Cells must be attached to a surface to divide.

Step-by-Step Guidance

1. Recall that cells need nutrients and growth factors to divide.

2. Think about how density-dependent inhibition prevents overcrowding.

3. Consider anchorage dependence, which requires cells to be attached to a substrate.

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Q10. How do cancers form, and how does this relate to the cell cycle?

Background

Topic: Cancer and Cell Cycle Regulation

This question tests your understanding of how loss of cell cycle control leads to cancer.

Key Terms:

• Proto-oncogenes: Promote cell division.

• Oncogenes: Mutated proto-oncogenes that cause uncontrolled division.

• Tumor-suppressor genes: Inhibit cell division.

• Transformation: Process by which normal cells become cancerous.

• Density-dependent inhibition: Loss leads to tumor formation.

Step-by-Step Guidance

1. Recall that cancer forms when cells lose control of the cell cycle and divide uncontrollably.

2. Think about how mutations in proto-oncogenes and tumor-suppressor genes contribute to this loss of control.

3. Consider the process of transformation, where normal cells become cancerous.

4. Describe how loss of density-dependent inhibition and anchorage dependence leads to tumor formation.

Try solving on your own before revealing the answer!