Biology: The Cell Cycle Flashcards
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Questions and Answers

What is cell division?

The reproduction of cells.

What is the cell cycle?

The life of a cell from the time it is first formed from a dividing parent cell until its own division into two daughter cells.

What is a genome?

The genetic material of an organism or virus.

What is a chromosome?

<p>A cellular structure consisting of one DNA molecule and associated protein molecules.</p> Signup and view all the answers

What is chromatin?

<p>The complex of DNA and proteins that makes up eukaryotic chromosomes.</p> Signup and view all the answers

What is a chromatid?

<p>One copy of the duplicated chromosome.</p> Signup and view all the answers

What is a centromere?

<p>The region on each sister chromatid where they are most closely attached to each other.</p> Signup and view all the answers

What are somatic cells?

<p>All body cells except the reproductive cells.</p> Signup and view all the answers

What are gametes?

<p>Reproductive cells; sperm and egg.</p> Signup and view all the answers

What are sister chromatids?

<p>A duplicated chromosome as two joined copies of the original chromosome.</p> Signup and view all the answers

What is mitosis?

<p>The division of genetic material in the nucleus.</p> Signup and view all the answers

What is cytokinesis?

<p>The division of the cytoplasm; follows mitosis.</p> Signup and view all the answers

What is the mitotic (M) phase?

<p>Includes mitosis and cytokinesis; usually the shortest part of the cell cycle.</p> Signup and view all the answers

What is interphase?

<p>Accounts for 90% of the cell cycle; can be divided into subphases G1, S, and G2.</p> Signup and view all the answers

What happens during prophase?

<p>Chromatin fibers become more tightly coiled and condense into chromosomes observable by a light microscope.</p> Signup and view all the answers

What is prometaphase?

<p>Nuclear envelope fragments and chromosomes have become even more condensed.</p> Signup and view all the answers

What occurs during metaphase?

<p>Chromosomes convene at the metaphase plate, centromeres are aligned at the center.</p> Signup and view all the answers

What happens in anaphase?

<p>Cohesin proteins are cleaved allowing sister chromatids to part and move towards opposite ends of the cell.</p> Signup and view all the answers

What happens during telophase?

<p>Two daughter nuclei form in the cell and the chromosomes become less condensed.</p> Signup and view all the answers

What is a mitotic spindle?

<p>Consists of fibers made of microtubules and associated proteins.</p> Signup and view all the answers

What is a centrosome?

<p>A subcellular region containing material that organizes the cell's microtubules.</p> Signup and view all the answers

What is an aster?

<p>A radial array of short microtubules.</p> Signup and view all the answers

What is a kinetochore?

<p>A structure made up of proteins that assemble on specific sections of chromosomal DNA.</p> Signup and view all the answers

What is binary fission?

<p>A method of asexual reproduction by division in half.</p> Signup and view all the answers

What is the origin of replication?

<p>Site where the replication of a DNA molecule begins.</p> Signup and view all the answers

What is the cell cycle control system?

<p>A cyclically operating set of molecules in the cell that triggers and coordinates key events in the cell cycle.</p> Signup and view all the answers

What is a checkpoint?

<p>A control point in the cell cycle where signals can regulate the cycle.</p> Signup and view all the answers

What is a growth factor?

<p>A protein released by certain cells that stimulates other cells to divide.</p> Signup and view all the answers

What is density-dependent inhibition?

<p>The phenomenon that causes normal animal cells to stop dividing when they come into contact with each other.</p> Signup and view all the answers

What is anchorage dependence?

<p>The requirement that a cell must be attached to a substratum in order to initiate cell division.</p> Signup and view all the answers

What are the functions of cell division?

<p>In prokaryotes or unicellular eukaryotes, it acts as reproduction; in multicellular organisms, it enables growth, development, and tissue renewal.</p> Signup and view all the answers

When is DNA replicated and why is this crucial?

<p>DNA is replicated during the S phase, which allows for cell division/mitosis.</p> Signup and view all the answers

What is the difference between replicated and unreplicated chromosomes?

<p>Replicated chromosomes have two identical DNA double helices, whereas unreplicated chromosomes have only a single DNA double helix.</p> Signup and view all the answers

Does mitosis change ploidy? How do daughter cells compare to the parent cell?

<p>Ploidy does not change during mitosis; daughter cells are the same as parent cells, diploids.</p> Signup and view all the answers

How does binary fission compare to cell division in eukaryotes?

<p>Binary fission is a kind of asexual reproduction that divides into two daughter cells, similar to mitosis.</p> Signup and view all the answers

What is the G0 phase?

<p>A nondividing state occupied by cells that have left the cell cycle.</p> Signup and view all the answers

How is control of the cell cycle related to cancer?

<p>Cancer cells do not respond to signals that normally regulate the cell cycle.</p> Signup and view all the answers

Study Notes

Cell Division and Cycle

  • Cell division is the process through which cells reproduce.
  • The cell cycle encompasses the life span of a cell from formation until its division into daughter cells.
  • The genome represents the entirety of genetic material in an organism or virus.

Chromosomes and Chromatin

  • Chromosomes consist of a single DNA molecule and associated proteins; eukaryotes have multiple linear chromosomes in the nucleus, while prokaryotes typically possess a single circular chromosome.
  • Chromatin refers to the DNA and protein complex in eukaryotes, existing as long thin fibers when the cell is not dividing.

Chromatids and Centromeres

  • A chromatid is one copy of a duplicated chromosome, attached to its identical copy by a centromere.
  • The centromere is the attachment point for sister chromatids, essential for proper chromosome movement during cell division.

Types of Cells

  • Somatic cells are all body cells excluding reproductive cells (gametes), which are the sperm and egg.

Mitosis and Cytokinesis

  • Mitosis refers to the division of the genetic material in the nucleus, while cytokinesis involves the division of the cytoplasm following mitosis.
  • The mitotic phase includes both mitosis and cytokinesis, typically the shortest phase of the cell cycle.

Interphase and Phases of Mitosis

  • Interphase accounts for 90% of the cell cycle and includes G1 (first phase), S (chromosome duplication), and G2 (final preparations for mitosis).
  • Prophase, prometaphase, metaphase, anaphase, telophase outline the stages of mitosis:
    • Prophase: Chromatin condenses into visible chromosomes; mitotic spindle begins to form.
    • Prometaphase: Nuclear envelope fragments; kinetochores develop on chromatids.
    • Metaphase: Chromosomes align at the metaphase plate with sister chromatids connected to microtubules from opposite poles.
    • Anaphase: Cohesin proteins are cleaved; sister chromatids move to opposite sides.
    • Telophase: Formation of daughter nuclei with reappearance of nucleoli and decondensation of chromosomes.

Cell Division Mechanisms

  • Cytokinesis differs between animal (cleavage furrow formation) and plant cells (cell plate formation).
  • The mitotic spindle, made of microtubules, organizes during cell division, initiated by the centrosome.

Regulatory Mechanisms

  • The cell cycle control system regulates cell cycle events through a series of checkpoints that monitor progress and signal when to divide or halt.
  • Major checkpoints are located in G1, G2, and M phases, ensuring proper division.
  • Growth factors are proteins that stimulate cell division, while density-dependent inhibition and anchorage dependence ensure cells stop dividing under certain conditions.

DNA Replication and Ploidy

  • DNA replication occurs during the S phase, crucial for ensuring each daughter cell inherits a complete set of chromosomes.
  • Replicated chromosomes consist of two identical DNA double helices; unreplicated chromosomes have a single double helix.
  • Mitosis does not alter ploidy; daughter cells remain diploid like the parent cell.

Binary Fission and Cell Cycle

  • Binary fission is a type of asexual reproduction found in prokaryotes and some eukaryotes, akin to mitosis in process.
  • G0 phase represents a non-dividing state for cells that have exited the cycle.
  • Cancer cells often bypass regulatory signals, leading to uncontrolled division.

Summary and Key Points

  • Cell division is essential for growth and repair in multicellular organisms.
  • The concerted actions of various phases, checkpoints, and regulatory mechanisms ensure a successful cell cycle, critical for maintaining healthy organismal function.

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Discover essential terms and definitions related to the cell cycle with this set of flashcards. Learn about key concepts such as cell division, chromosomes, and genomes to enhance your understanding of cellular biology.

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