Cell Division and the Cell Cycle
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Questions and Answers

What process follows nuclear division in cell division?

  • Interphase
  • Karyokinesis
  • Metaphase
  • Cytokinesis (correct)

Which phases make up interphase?

  • Prophase, Metaphase, and Anaphase
  • Mitosis, Cytokinesis, and G1
  • Telophase, Cytokinesis, and G0
  • G1, S, and G2 phases (correct)

What occurs when the surface to volume ratio is small?

  • Cellular metabolism increases
  • Cell division is enhanced
  • Mitosis is initiated
  • Cell growth becomes inefficient (correct)

When does interphase begin in the cell cycle?

<p>When cytokinesis is complete (D)</p> Signup and view all the answers

What is the role of the spindle apparatus during cell division?

<p>To facilitate chromosome alignment and separation (A)</p> Signup and view all the answers

What is the primary outcome of meiosis?

<p>Four non-identical haploid daughter cells are produced. (C)</p> Signup and view all the answers

During which stage of meiosis does crossing over occur?

<p>Prophase I (D)</p> Signup and view all the answers

What occurs in meiosis II?

<p>Sister chromatids are separated. (C)</p> Signup and view all the answers

Which statement about genetic variation from meiosis is incorrect?

<p>Meiosis results in identical daughter cells. (B)</p> Signup and view all the answers

What is the significance of the nuclear envelope during metaphase?

<p>It disassembles completely before metaphase. (B)</p> Signup and view all the answers

During which phase of mitosis do chromosomes line up at the cell's equator?

<p>Metaphase (D)</p> Signup and view all the answers

What occurs during anaphase in mitosis?

<p>Microtubules shorten and pull sister chromatids apart (D)</p> Signup and view all the answers

What is the result of mitosis in terms of chromosome number in each daughter cell?

<p>46 chromosomes and 46 chromatids (A)</p> Signup and view all the answers

What marks the transition from metaphase to anaphase during mitosis?

<p>Sister chromatids being pulled apart (B)</p> Signup and view all the answers

In which phase does chromatin decondense back into its relaxed form?

<p>Telophase (B)</p> Signup and view all the answers

What happens during the G1 phase of the cell cycle?

<p>Cells prepare for division by increasing in size. (A)</p> Signup and view all the answers

Which phase is characterized by the replication of DNA?

<p>S phase (C)</p> Signup and view all the answers

What is the function of centrioles in animal cells?

<p>They produce spindle fibers. (A)</p> Signup and view all the answers

What limits how large animal cells can grow?

<p>The surface area to volume ratio. (A)</p> Signup and view all the answers

How do microtubule inhibitors function as anti-tumor drugs?

<p>They stabilize microtubules. (C)</p> Signup and view all the answers

Flashcards

Cell Division

The process of duplication of the cell that includes karyokinesis (nuclear division) and cytokinesis (cytoplasmic division).

The Cell Cycle

The complete process of a cell's life, from birth to division.

Interphase

The preparatory phase for mitosis, where the cell grows, replicates its DNA, and prepares for cell division.

Surface to Volume Ratio (S/V)

The ratio of a cell's surface area to its volume. It's important in determining how efficiently nutrients can be transferred into the cell.

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The Spindle Apparatus

A structure composed of microtubules that helps separate chromosomes during cell division. It plays a key role in ensuring that each daughter cell receives a complete set of chromosomes.

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Mitotic phase

The phase of the cell cycle when the nucleus divides.

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Centrioles

A pair of cylindrical structures located near the nucleus that are involved in the formation of spindle fibers during mitosis.

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Metaphase

The stage of mitosis where duplicated chromosomes align at the center of the cell.

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Anaphase

The stage of mitosis where duplicated chromosomes separate and move to opposite poles of the cell .

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Telophase and cytokinesis

The stage of mitosis where the nuclear envelope reforms and two daughter cells begin to form.

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Crossing Over

The process where homologous chromosomes pair up and exchange genetic material, resulting in new combinations of alleles.

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Meiosis I

The first division in meiosis where homologous chromosomes separate, reducing the number of chromosomes from diploid to haploid.

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Meiosis II

The second division in meiosis where sister chromatids separate, resulting in four haploid daughter cells.

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Genetic Recombination

The process that creates new combinations of genes, enhancing genetic diversity.

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Centrosomes

Structures in animal cells that contain a pair of centrioles and play a crucial role in cell division.

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G1 Phase

The process by which cells grow larger in volume and replicate their organelles before entering the S phase of the cell cycle.

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S Phase

A phase in the cell cycle where the DNA is replicated, creating two identical copies of each chromosome, called sister chromatids.

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Study Notes

Cell Division

  • Cell division is the process of a cell dividing into two new daughter cells
  • It involves karyokinesis (nuclear division) followed by cytokinesis (cytoplasmic division)
  • Diploid cells have two copies of each chromosome, forming homologous pairs
  • Humans have 46 chromosomes (23 pairs)
  • Centrosomes contain centrioles that produce spindle fibers for separating sister chromatids.

The Cell Cycle

  • The cell cycle includes interphase (G1, S, G2) and the mitotic phase (mitosis + cytokinesis)
  • Interphase follows mitosis and cytokinesis, where cells grow and replicate to enter the interphase stage
  • G1: Cell growth, protein production, ribosome and mitochondria replication, and organelle replication
  • S: DNA synthesis (DNA replication, creating sister chromatids); this occurs during the synthesis phase, not mitosis
  • G2: Continued cell growth, preparation of genetic material for division, and replication of some organelles
  • G0: Inactive state for cells not actively growing or dividing (e.g., nerve or cardiac cells)
  • Surface-to-Volume ratio is important; as cells increase in size, the ratio gets smaller and cellular exchange is harder, potentially leading to division to increase surface area
  • Genome-to-Volume ratio is also crucial. As the cell gets too large, it may exceed its genome's ability to produce necessary proteins for regulating cell activities.

Mitosis

  • Prophase: Nucleus disassembles, nucleolus disappears, chromatin condenses into chromosomes, and spindle fibers form
  • Metaphase: Chromosomes line up, each consisting of sister chromatids. Kinetochores attach to microtubules.
  • Anaphase: Microtubules shorten, pulling apart sister chromatids into separate chromosomes (disjunction) towards opposite poles. Chromosomes double.
  • Telophase and cytokinesis: Nuclear envelope reforms, chromosomes decondense, nucleoli reappear. This results in 2 diploid cells (with 46 chromosomes each) after division.

Meiosis

  • Meiosis produces four non-identical haploid cells from one diploid parent cell. It involves two nuclear divisions (meiosis 1 and meiosis 2).
  • Prophase I: Spindle forms, homologous chromosomes synapse forming tetrads, allowing crossing over to happen. Microtubules attach to chromosomes at kinetochores.
  • Metaphase I: Homologous chromosomes arranged randomly at the metaphase plate (independent assortment).
  • Anaphase I: Homologous chromosomes separate, directed by spindle fibers to opposite poles
  • Telophase I and cytokinesis: Homologous chromosomes separate; results in two haploid (23 chromosomes) daughter cells.
  • Prophase II-Telophase II: Similar to mitosis, with sister chromatids separating. Cytokinesis again produces 4 haploid cells.

Sources of Genetic Variation

  • Crossing over (non-sister chromatids exchange genetic material during prophase I)
  • Independent assortment (random orientation of homologous chromosomes in metaphase I)
  • Random joining of gametes (which sperm fertilizes which egg)

Comparing Meiosis and Mitosis

Feature Meiosis Mitosis
Chromosome # Reduced by half (from 46 to 23) Remains the same (46)
Daughter cells 4 haploid cells 2 diploid cells
Genetic makeup Genetically diverse Genetically identical
Cell division 2 rounds 1 round
Genetic info Sister chromatids separate in anaphase II, homologous chromosomes separate in anaphase I Sister chromatids separate in anaphase

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Description

This quiz covers the essential concepts of cell division and the cell cycle, including the processes of karyokinesis and cytokinesis. It delves into the stages of the cell cycle, such as interphase and mitotic phases, and highlights the roles of diploid cells and centrosomes in cell division.

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