Cell Cycle and Mitosis Overview

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Questions and Answers

What is the primary role of the centromere in chromosomes?

It connects the two sister chromatids during cell division. (correct)

It contains the genetic sequence that codes for proteins.

It prevents the loss of DNA during replication.

It holds the DNA tightly together to prevent tangling.

During which phase of the cell cycle are chromosomes visible?

Mitosis (correct)

Cytokinesis

G1 phase

Interphase

How is chromatin different from chromosomes?

Chromatin is condensed DNA, while chromosomes are uncondensed DNA.

Chromatin is uncondensed and folded, while chromosomes are folded and condensed. (correct)

Chromatin is made up of nucleosomes, while chromosomes are made of chromatids.

Chromatin is found only during cell division, whereas chromosomes are always present.

What happens during interphase?

Chromosomes are duplicated and prepare for division. (B) Signup and view all the answers

What characteristic do homologous chromosomes share?

They have the same centromere position and carry the same genes. (D) Signup and view all the answers

What do telomeres do at the ends of chromatids?

They prevent the loss of important genetic information during replication. (C) Signup and view all the answers

What composition forms a nucleosome?

DNA wrapped around 8 histone molecules. (A) Signup and view all the answers

What is the first event that occurs during cytokinesis in animal cells?

Disassembling of spindle fibres (A) Signup and view all the answers

What is the role of spindle fibres during anaphase?

Pull sister chromatids to opposite poles (C) Signup and view all the answers

Which of the following statements about chromatids is correct?

Each chromatid contains one DNA molecule (D) Signup and view all the answers

In plant cells, what structure forms between two daughter cells during cytokinesis?

Cell plate (C) Signup and view all the answers

What happens to the spindle fibres during prophase?

They attach to chromosomes (D) Signup and view all the answers

Why is the centromere important for sister chromatids?

It allows the spindle fibres to attach (B) Signup and view all the answers

What critical process is initiated during telophase but is not considered part of mitosis?

Cytokinesis (C) Signup and view all the answers

Which advantage does a light microscope have over an electron microscope for studying the cell cycle?

Ability to view living cells (D) Signup and view all the answers

What is the outcome of cytokinesis?

Two genetically identical daughter cells (D) Signup and view all the answers

What occurs during the G1 phase of the cell cycle?

The cell takes in material and grows. (C) Signup and view all the answers

Which of the following statements accurately describes the S phase?

DNA replicates to form identical copies. (D) Signup and view all the answers

What is the main function of the G2 phase?

Error checking and repair of new DNA. (B) Signup and view all the answers

During which phase of mitosis do the chromosomes become visible as sister chromatids?

Prophase (C) Signup and view all the answers

What happens to the chromatids during anaphase?

Chromatids are pulled apart toward opposite poles. (B) Signup and view all the answers

Which process marks the end of the mitotic phase?

Telophase (C) Signup and view all the answers

What is the significance of the centrosome during prophase?

It replicates just before prophase. (C) Signup and view all the answers

How do plant cells differ from animal cells in the mitosis process?

They do not have a centriole. (D) Signup and view all the answers

What initiates the formation of the spindle during prophase?

Centrioles move to opposite poles. (D) Signup and view all the answers

Study Notes

Cell Development and Diversity & Conservation

Cells reproduce through a cycle called the cell cycle.
The cell cycle has three main phases: interphase, nuclear division (mitosis), cell division (cytokinesis).
Interphase: Cell growth and preparation for division.
Mitosis: Division of the nucleus.
Cytokinesis: Division of the cytoplasm.
Interphase stages.
- G1 phase: First growth phase. Includes protein synthesis and organelle replication. Cell size increases.
- S phase: Synthesis phase. DNA replicates. Chromosomes become double-stranded.
- G2 phase: Second growth phase. Cell continues growing, organelles replicated and DNA is checked.
Mitosis stages:
- Prophase: Chromosomes condense and become visible. Centrioles move to opposite poles. Nuclear membrane breaks down.
- Metaphase: Chromosomes align at the metaphase plate.
- Anaphase: Sister chromatids separate and move to opposite poles.
- Telophase: Chromosomes decondense. Nuclear membranes reform. Nucleoli reappear.
Mitosis(cell division) in plants
Plant cells lack centrioles.
A new cell wall forms between the two daughter cells.
Vesicles carrying cell wall materials are guided to the equator of the cell by spindle fibers.
Vesicles fuse then form a new cell plate separating the two daughter cells.
Role of spindle fibers.
- Spindle fibers attach to centromeres at the kinetochore.
- Arrange chromosomes at the equator.
- Pull sister chromatids to opposite poles.
Cytokinesis
Cytoplasmic division.
Involves a contractile ring in animal cells.
Involves a cell plate formation in plant cells
Centrioles are not found in plant cells
Mitosis produces genetically identical cells.

Chromosome Structure

DNA forms a thread-like structure called chromatin.
Chromatin coils around histone proteins, which are proteins which organize the DNA to form nucleosomes.
Nucleosomes form a compact structure called chromatin fibers.
Chromosomes are formed through condensation of chromatin fibers.
The number of chromosomes is characteristic of a species.
At both ends of a chromatid are regions called telomeres that protect DNA from loss during replication.

Chromatin vs. Chromosome

Chromatin and chromosomes are essentially the same material (DNA) but in different forms.
Chromatin is the uncondensed, uncoiled form of DNA, found mainly during interphase.
Chromosomes are the condensed, coiled form of DNA found during cell division.
They are basically the same but differ structurally and functionally.

Importance of Cell Cycle

Growth
Repair: Damaged cells are replaced.
Asexual reproduction: Genetically identical organisms are produced.

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Description

Explore the essential phases of the cell cycle, including interphase, mitosis, and cytokinesis. Learn about each stage's details, from cell growth to the division of the nucleus and cytoplasm. This quiz will test your understanding of cellular reproduction and its significance.