Biology Chapter 10: Cell Cycle and Division

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Questions and Answers

What is the main outcome of the cell cycle?

Production of two daughter cells (correct)

Synthesis of DNA only

Formation of a single daughter cell

Replication of organelles only

Which processes must occur in a coordinated way during cell division?

Energy production and organelle duplication

Protein synthesis and cell growth

Cell division, DNA replication, and cell growth (correct)

DNA replication and cytoplasm division

How do newly formed daughter cells contribute to the growth of an organism?

By combining their DNA with parental cells

By dying shortly after division

By themselves repeating cycles of growth and division (correct)

By undergoing direct cell fusion

What does the cell cycle include besides cell division?

DNA replication and cell growth Signup and view all the answers

What term describes the sequence of events through which a cell duplicates its genome and divides?

Cell cycle Signup and view all the answers

What occurs during the G1 phase of the interphase?

The cell is metabolically active and grows. Signup and view all the answers

If the initial amount of DNA per cell is 2C, what will it be after the S phase?

4C Signup and view all the answers

What occurs during the G2 phase of interphase?

Cell growth and preparation for mitosis happen. Signup and view all the answers

In animal cells, which structure duplicates during the S phase?

Centriole Signup and view all the answers

Which of these statements is true regarding chromosome number after the S phase?

The number of chromosomes stays the same. Signup and view all the answers

What is the primary purpose of cytokinesis in cell division?

To divide the cell itself into two daughter cells Signup and view all the answers

How does cytokinesis differ in animal cells compared to plant cells?

Animal cells form a furrow, while plant cells form a cell plate Signup and view all the answers

What structure forms in plant cells during cytokinesis?

Cell plate Signup and view all the answers

In what scenario might karyokinesis occur without cytokinesis?

In the formation of a syncytium Signup and view all the answers

What is the primary role of the cell-plate during plant cell cytokinesis?

To represent the middle lamella between adjacent cells Signup and view all the answers

What occurs during the leptotene stage of Prophase I in meiosis?

Chromosomes become visible under a light microscope. Signup and view all the answers

What is a bivalent in the context of meiosis?

A pair of homologous chromosomes that have undergone synapsis. Signup and view all the answers

Which phase of meiosis I involves the pairing of homologous chromosomes?

Prophase I Signup and view all the answers

What structure is formed during the zygotene stage of Prophase I?

Synaptonemal complex. Signup and view all the answers

How many haploid cells are produced at the end of meiosis II?

Four haploid cells Signup and view all the answers

What is the primary event occurring during the pachytene stage of prophase I?

Chromatids becoming distinct and forming tetrads Signup and view all the answers

What characterizes the beginning of the diplotene stage?

Dissolution of the synaptonemal complex Signup and view all the answers

What is the role of the enzyme recombinase during crossing over?

To facilitate the exchange of genetic material Signup and view all the answers

What happens by the end of diakinesis?

The nucleolus and nuclear envelope disappear Signup and view all the answers

Which structures represent the sites where crossing over occurs?

Recombination nodules Signup and view all the answers

Study Notes

Cell Cycle Overview

All organisms originate from a single cell through processes of growth and reproduction.
Cell division results in two daughter cells from a parental cell, contributing to the formation of large organisms from a solitary cell.
The cell cycle encompasses DNA replication, cell growth, and division in a coordinated manner to ensure intact genome distribution to daughter cells.

Phases of the Cell Cycle

Interphase consists of three phases:
- G1 Phase (Gap 1): Active metabolism and growth without DNA replication.
- S Phase (Synthesis): DNA replication occurs, doubling the amount of DNA from 2C to 4C while chromosome number (2n) remains unchanged.
- G2 Phase (Gap 2): Protein synthesis and further cell growth preparing for mitosis.

M Phase

Mitosis involves two main processes:
- Karyokinesis: Segregation of duplicated chromosomes into daughter nuclei.
- Cytokinesis: Division of the cytoplasm into two separate daughter cells.
In animal cells, cytokinesis occurs through the formation of a furrow that deepens to split the cell.
In plant cells, cytokinesis involves the formation of a cell plate, expanding outward to meet existing cell walls.

Importance of Mitosis

Essential for growth, tissue repair, and reproduction in organisms.
Mitosis ensures that each daughter cell receives an identical set of chromosomes.

Meiosis Overview

Initiated after DNA replication to produce sister chromatids.
Meiosis consists of two divisions:
- Meiosis I: Homologous chromosomes pair up and recombination occurs.
- Meiosis II: Similar to mitosis, leading to the separation of sister chromatids.

Phases of Meiosis I

Prophase I is longer and complex, divided into five phases:
- Leptotene: Chromosomes become visible and compact.
- Zygotene: Chromosomes begin synapsis, forming homologous pairs (bivalents).
- Pachytene: Characterized by distinct tetrads and the formation of recombination nodules; crossing over occurs, leading to genetic recombination via the enzyme recombinase.
- Diplotene: Homologous chromosomes separate except at chiasmata where crossing over occurred; this stage can last long in oocytes of some vertebrates.
- Diakinesis: Chromosomes condense completely, the nuclear envelope breaks down, signaling transition to metaphase.

Metaphase I

Bivalent chromosomes align on the equatorial plate, with spindle microtubules attaching to the kinetochores of each homologous chromosome.

Conclusion

Both mitosis and meiosis are critical processes in the life cycle of cells, contributing to growth, reproduction, and genetic diversity.

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Description

Explore the fascinating processes of the cell cycle and cell division in this quiz based on Biology Chapter 10. Test your understanding of how a single cell can develop into a complex organism, a fundamental concept in biology. Perfect for reinforcing key concepts and terminology related to cell growth and reproduction.