Cell Cycle: Interphase, Growth, and DNA Replication
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Questions and Answers

During which phase of the cell cycle does DNA replication occur?

  • Prophase
  • G2 phase
  • G1 phase
  • S phase (correct)

Which of the following events does NOT occur during interphase?

  • DNA replication
  • Protein synthesis
  • Cell growth
  • Separation of sister chromatids (correct)

At what stage of mitosis do sister chromatids separate and migrate to opposite poles?

  • Prophase
  • Metaphase
  • Anaphase (correct)
  • Telophase

Which structure is responsible for moving chromosomes during mitosis?

<p>Spindle fibers (A)</p> Signup and view all the answers

What is the main event that characterizes cytokinesis in animal cells?

<p>Pinching apart of the plasma membrane (D)</p> Signup and view all the answers

During which phase of mitosis do the chromosomes line up in the center of the cell?

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

Which of the subsequent events occurs during prophase?

<p>Chromosomes condense and become visible. (A)</p> Signup and view all the answers

If a cell has 20 chromosomes during G1 phase, how many sister chromatids will it have during prophase?

<p>40 (D)</p> Signup and view all the answers

Which of the following is the correct order of the phases of mitosis?

<p>Prophase, Metaphase, Anaphase, Telophase (B)</p> Signup and view all the answers

What is the primary function of the G2 phase in the cell cycle?

<p>Preparation for mitosis (A)</p> Signup and view all the answers

A cell in G2 phase has twice the amount of DNA as a cell in G1 phase. What process is directly responsible for this change?

<p>DNA replication during S phase. (D)</p> Signup and view all the answers

What would be the most likely outcome if spindle fibers failed to form during mitosis?

<p>Sister chromatids would not separate properly. (A)</p> Signup and view all the answers

A researcher treats cells with a chemical that prevents cytokinesis. If mitosis occurs normally, what would be the likely result?

<p>Cells would have multiple nuclei. (D)</p> Signup and view all the answers

In animal cells, what is the primary mechanism by which cytokinesis occurs?

<p>Formation of a cleavage furrow. (C)</p> Signup and view all the answers

How does the function of the centromere change from prophase to anaphase?

<p>It holds sister chromatids together and then is cleaved, allowing separation. (D)</p> Signup and view all the answers

If a scientist observes a cell with condensed chromosomes aligned along the middle of the cell, which phase is the cell most likely in?

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

Which event marks the beginning of anaphase?

<p>The separation of sister chromatids. (C)</p> Signup and view all the answers

What cellular component is responsible for organizing the spindle fibers that attach to chromosomes during mitosis?

<p>The centrioles. (D)</p> Signup and view all the answers

Why is it important for chromosomes to condense during mitosis?

<p>To facilitate the movement of chromosomes without tangling or breaking. (B)</p> Signup and view all the answers

What would happen if a cell proceeds through the cell cycle with a mutation that disables the G2 checkpoint?

<p>The cell would divide, even if DNA replication was incomplete or errors exist. (A)</p> Signup and view all the answers

What is the primary function of the S phase within interphase?

<p>Replicating DNA to produce identical copies (B)</p> Signup and view all the answers

During which phase of mitosis do the spindle fibers pull sister chromatids apart?

<p>Anaphase (A)</p> Signup and view all the answers

Which event directly precedes the beginning of cytokinesis?

<p>Formation of two separate nuclei (B)</p> Signup and view all the answers

What distinguishes cytokinesis in animal cells from cytokinesis in plant cells?

<p>Plant cells form a cell plate, while animal cells pinch apart. (A)</p> Signup and view all the answers

During which phase of mitosis do the chromosomes align along the metaphase plate?

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

What initiates the process of mitosis?

<p>Thickening and visibility of chromosomes (D)</p> Signup and view all the answers

Which of the following events occurs during prophase?

<p>Chromosomes condense and become visible. (A)</p> Signup and view all the answers

If a cell completed interphase and contains 40 sister chromatids total, how many chromosomes will each daughter cell have after mitosis and cytokinesis are complete?

<p>20 (A)</p> Signup and view all the answers

What is the relative duration of interphase versus mitosis in the cell cycle?

<p>Interphase constitutes the majority of the cell cycle. (B)</p> Signup and view all the answers

What role do centrioles play during mitosis?

<p>They move to opposite ends of the cell and organize the spindle fibers. (B)</p> Signup and view all the answers

Flashcards

Cell Cycle

The life cycle of a cell, including interphase and cell division.

Interphase

The longest phase of the cell cycle where the cell grows and prepares for division.

G1 Phase

Cell growth; increase in organelles and cytoplasm.

S Phase

DNA replication; chromosomes make identical copies.

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G2 Phase

Cell prepares for mitosis, makes organelles and substances.

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Mitosis

Cell division resulting in two identical nuclei.

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Prophase

Chromosomes condense and become visible; nuclear envelope disappears.

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Metaphase

Chromosomes align in the center of the cell.

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Anaphase

Sister chromatids separate and move to opposite ends of the cell.

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Telophase

Two nuclei form; cleavage furrow begins.

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What is Interphase

The time during the cell cycle when the cell isn't dividing but is very active, performing normal life functions.

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What are Sister Chromatids?

Identical copies of a chromosome, joined at the centromere during S phase.

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What is a Centromere?

The structure that holds sister chromatids together.

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What are Spindle Fibers?

Microtubules that connect centrioles to the centromeres of sister chromatids during prophase.

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What is a Cell Plate?

The structure that forms to divide a plant cell during cytokinesis.

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What is Cytokinesis?

The process where the cytoplasm splits, dividing the cell into two.

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What is a Cleavage Furrow?

The pinching in of the plasma membrane during cytokinesis in animal cells.

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What are Centrioles?

The structures that move to opposite ends of the cell during prophase.

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What is the Nuclear Envelope?

The reappearance of this structure occurs during telophase.

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What is the Nucleolus?

The disappearance of this structure occurs during prophase.

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What is the cell like during Interphase?

The stage where a cell is not dividing but is actively carrying out its normal functions.

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What are Spindle Fibers made of?

Microtubules that extend from the centrioles and attach to the centromeres during cell division.

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What structure is unique to plant cell division?

The structure that divides plant cells during cytokinesis.

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How do animal cells physically divide?

The process where the cell membrane pinches inward to divide the cell, primarily in animal cells.

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What is created during the G2 phase?

Organelles and substances are created to prepare for the upcoming cell division.

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Mitosis definition

Series of phases involved in a nucleus dividing in two identical nuclei.

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What happens during Prophase?

The nucleolus and nuclear envelope begin to disappear and chromosomes thicken

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What happens during Metaphase?

The chromosomes are moved to the center of the cell by spindle fibers.

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What happens during Anaphase?

Sister chromatids are separated and migrate to opposite ends of the cell.

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What happens during Telophase?

Two separate nuclei begin to form and a cleavage furrow begins to form.

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Study Notes

  • The cell cycle describes the life cycle of a cell.
  • The life of a cell can be divided into two main categories: interphase and cell division.

Interphase

  • Interphase, when the cell is not dividing, constitutes the busiest period in the cell's life, making up 75% of the cell cycle.
  • During interphase, the nucleus and nucleolus are visible, and normal cell functions like ATP production and protein synthesis occur.
  • Chromatin exists as thin and tangled strands.
  • Interphase consists of three phases: G1, S phase, and G2.

G1 Phase (Cell Growth)

  • There is an increase in the number of organelles and the amount of cytoplasm

S Phase (DNA Replication)

  • Chromosomes replicate to produce identical copies.
  • The centromere holds the identical chromosome copies together.
  • Sister chromatids is the collective term for the identical copies.
  • Sister chromatids are too thin to see.

G2 Phase (Preparation for Mitosis)

  • The cell produces organelles and substances needed for cell division

Cell Division

  • Cell division includes two main steps: mitosis and cytokinesis.

Mitosis

  • Mitosis is a series of phases resulting in the division of one nucleus into two identical nuclei.

Prophase

  • The nucleolus and nuclear envelope disappear.
  • Chromosomes thicken and become visible, appearing as sister chromatids.
  • The centrioles migrate to opposite poles of the cell.
  • Spindle fibers made of microtubules form and connect the centrioles to the centromeres of each sister chromatid.
  • The nuclear envelope dissolves.

Metaphase

  • Spindle fibers attached to the centromeres move the chromosomes to the cell's center.

Anaphase

  • Spindle fibers separate sister chromatids at the centromere, and the chromatids migrate to opposite ends of the cell.
  • Each chromatid is now a separate chromosome.

Telophase

  • Chromosomes arrive at the poles, and two new nuclei begin to form.
  • A cleavage furrow forms as the cell membrane pinches, marking the start of cytokinesis.

Cytokinesis

  • The cell starts to split.
  • The cytoplasm divides.
  • A cell plate divides plant cells.
  • The plasma membrane pinches apart in animal cells.
  • The nucleolus and nuclear membrane reappear.
  • Chromosomes uncoil, reverting to chromatin form.
  • This process results in two identical diploid daughter cells.

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The Cell Cycle Notes PDF

Description

Explore the cell cycle, focusing on interphase, the busiest part of a cell's life. Learn about the G1 phase, where organelles increase, and the S phase, where DNA replicates to form sister chromatids. Understand how cells prepare for mitosis during the G2 phase.

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