Genetics and Cell Division Quiz

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Questions and Answers

What mechanism is primarily responsible for maintaining genetic variation in a population?

Non-random mating

Random mating (correct)

Asexual reproduction

Chromosomal duplication

What does the process of crossing over during meiosis contribute to?

Reduction of genetic mutations

Increased genetic diversity (correct)

Creation of identical genetic copies

Formation of a diploid organism

How does non-random mating affect genetic variation in a population?

It only affects allele frequency

It has no effect on genetic variation

It reduces genetic variation (correct)

It enhances genetic variation

What is a consequence of a population bottleneck?

Loss of genetic variation Signup and view all the answers

During which phase do chromosomes align on the metaphase plate?

Metaphase I Signup and view all the answers

Which of the following contributes to genetic variation through chromosomal assortment?

Independent assortment Signup and view all the answers

Which statement is true regarding the outcome of genetic variation maintenance mechanisms?

They ensure a decrease in genetic similarity Signup and view all the answers

What is the role of fertilization in genetic variation?

It combines genetic material from two parents Signup and view all the answers

Which of the following correctly describes a key difference between mitosis and meiosis?

Mitosis results in two identical daughter cells while meiosis results in four genetically diverse cells. Signup and view all the answers

What are kinetochores primarily involved in during mitosis and meiosis?

Facilitating the separation of chromosomes. Signup and view all the answers

Which protein complex is primarily responsible for regulating the progression of the cell cycle?

Cyclin-dependent protein kinase (Cdk) complex. Signup and view all the answers

What is a consequence of nondisjunction during meiosis?

Formation of gametes with abnormal chromosome numbers. Signup and view all the answers

Which molecule plays a crucial role in the inhibition of the cell cycle?

p53. Signup and view all the answers

What is the evolutionary advantage of sexual reproduction?

It enhances adaptation and genetic diversity within populations. Signup and view all the answers

During which stage of meiosis does crossing over occur?

Prophase I. Signup and view all the answers

Which of the following components are NOT directly involved in mitosis?

Actin filaments. Signup and view all the answers

What would happen to gametes during sexual reproduction?

Gametes would remain haploid. Signup and view all the answers

Why did the Gros Michel banana become susceptible to diseases?

It had the same genetic material, limiting resistance. Signup and view all the answers

Which banana cultivar became dominant after the Gros Michel?

Cavendish Signup and view all the answers

How does sexual reproduction contribute to genetic variation?

By combining genetic material from two parents. Signup and view all the answers

What is a consequence of asexual reproduction in the context of banana cultivation?

Limited genetic diversity. Signup and view all the answers

What is the primary benefit of sexual reproduction in unicellular organisms?

It increases adaptability to harsh environments. Signup and view all the answers

Which phase of the cell cycle is characterized by DNA synthesis?

S phase Signup and view all the answers

In the process of flow cytometry, what measurement indicates DNA content within cells?

Fluorescence intensity Signup and view all the answers

What is the purpose of checkpoints in the cell cycle?

To ensure cells are ready to proceed to the next phase. Signup and view all the answers

Which of the following factors primarily drives the cyclin-dependent protein kinases (Cdk) activity?

Accumulation of cyclins at specific times. Signup and view all the answers

During which checkpoint is a cell assessed for DNA damage before mitosis?

G2/M checkpoint Signup and view all the answers

What type of enzyme is primarily responsible for phosphorylating proteins in the cell cycle?

Kinase Signup and view all the answers

What could a shift in the peaks of DNA content measured by flow cytometry indicate about a cell population?

Cells are progressing towards mitosis. Signup and view all the answers

What role do cyclins play in relation to Cdk?

They activate Cdk to phosphorylate other proteins. Signup and view all the answers

Why is it crucial to have multiple ways to modulate Cdk activity?

To allow precise control of cell cycle progression. Signup and view all the answers

What happens to Cdk activity during the cell cycle?

It fluctuates depending on cyclin concentration. Signup and view all the answers

Which of the following mechanisms does NOT regulate Cdk activity?

Synthesis of new cyclins. Signup and view all the answers

How do checkpoints in the cell cycle influence Cdk activity?

They prevent cells from progressing if conditions are not favorable. Signup and view all the answers

Which of the following statements about M-cyclin is correct?

M-cyclin concentration varies throughout the cell cycle. Signup and view all the answers

What would likely occur if regulatory mechanisms controlling Cdk malfunctioned?

Cell cycle progression could become unchecked. Signup and view all the answers

Which factor does NOT contribute to the control of Cdk complexes?

Nutrient availability in the environment. Signup and view all the answers

What is the primary role of p53 in the regulation of the cell cycle?

Suppresses tumor formation Signup and view all the answers

Which statement about p21 is correct regarding its function in the cell cycle?

It inhibits cyclin-dependent kinases Signup and view all the answers

What would likely be the consequence of p53 mutation in a cell?

Unregulated cell division Signup and view all the answers

What is the role of cohesins during cell division?

They hold sister chromatids together Signup and view all the answers

How does the activation of Cdc25 contribute to the cell cycle?

By dephosphorylating M-Cdk Signup and view all the answers

What is the function of the APC/C in cell division?

To tag securin with ubiquitin Signup and view all the answers

Which of the following is NOT associated with the regulation of the S phase?

Wee1 Signup and view all the answers

What role do condensins play in mitosis?

They condense chromosomes Signup and view all the answers

Study Notes

Cell Division Cycle and Meiosis

The Cell Division Cycle and Meiosis are covered in chapters 18 and 19 of the "Essential Cell Biology" textbook, pages 635-666 and 677-689.
The images are from the 5th edition of the textbook.

Learning Objectives

1. Compare and contrast mitosis and meiosis, including when and where each process occurs.
2. Investigate the roles of the mitotic spindle, microtubules, actin, myosin, kinetochores, condensin, and cohesins in mitosis, meiosis, and cytokinesis.
3. Distinguish the stages of mitosis or meiosis from descriptions or figures.
4. Describe the evolutionary advantage of sexual reproduction and analyze the processes leading to genetic variation.
5. Illustrate ways meiosis can fail to separate chromosomes correctly, and explain the consequences of nondisjunction.
6. Differentiate the ways cells regulate progression through the cell cycle.
7. Explain how cyclins, cyclin-dependent protein kinases (Cdks), and cyclin-dependent kinase inhibitors (CKIs) coordinate the promotion or inhibition of cell cycle progression.
8. Predict the outcomes of mutations in cell cycle regulatory proteins and provide supporting evidence.

Mitosis vs. Meiosis

Key Differences: Mitosis produces two identical diploid daughter cells. Meiosis produces four unique haploid daughter cells.
Key Processes: Mitosis involves one round of cell division, while meiosis involves two. Mitosis replicates once. Meiosis has crossing over.

Terminology

Sister chromatids: Exact copies of a chromosome generated during the S phase.
Homologous chromosomes: A pair of chromosomes (one maternal, one paternal) with similar genes but potentially different alleles. Non-sister chromatids are in a homologous pair.

Meiosis I

Prophase I: Homologous chromosomes pair up and exchange genetic material (crossing over). Nuclear envelope fragments.
Metaphase I: Homologous chromosome pairs are aligned at the metaphase plate.
Anaphase I: Homologous chromosomes separate and move to opposite poles.
Telophase I and Cytokinesis: Chromosomes arrive at the poles, nuclear envelopes reform. Cytoplasm divides, producing two haploid cells.

Meiosis II

Prophase II: Sister chromatids condense. Nuclear envelope fragments (if reformed).
Metaphase II: Sister chromatids align at the metaphase plate.
Anaphase II: Sister chromatids separate and move to opposite poles.
Telophase II and Cytokinesis: Chromosomes arrive at the poles, nuclear envelopes reform. Cytoplasm divides, resulting in four haploid cells.

Genetic Variation

Random mating, crossing over, and independent assortment contribute to genetic variation in sexually reproducing organisms.

Nondisjunction

Error in meiosis where homologous chromosomes or sister chromatids fail to separate properly.
Leads to aneuploid gametes (incorrect number of chromosomes) resulting in offspring with chromosomal abnormalities.

Cell Cycle Control System

Cyclins, Cdks, CKIs, Rb, E2F, and p53 regulate cell cycle progression.
Checkpoints (G1/S, G2/M, and M) ensure proper DNA replication and chromosome segregation before proceeding to the next phase.
Flow cytometry can measure and analyze different cell cycle stages.

Other Key Concepts

Asexual reproduction produces genetically identical offspring.
Mutations in somatic cells are not typically passed to offspring.
Sexual reproduction increases genetic diversity.
Gametes are specialized sex cells.

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Description

Test your knowledge on the mechanisms maintaining genetic variation and the processes involved in meiosis and mitosis. This quiz covers key concepts such as crossing over, non-random mating, and the consequences of population bottlenecks. Get ready to explore the intricate world of genetics and cell division!