Cell Biology Chapter: Mitosis and Meiosis Quiz

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Questions and Answers

What is the primary purpose of mitosis in multicellular organisms?

To enable growth and repair throughout their lifetime (correct)

To produce sex cells for reproduction

To ensure the reproduction of the entire organism

To increase genetic diversity in offspring

What characterizes somatic cells in terms of chromosome sets?

They have four sets of chromosomes

They have two sets of chromosomes (correct)

They have a variable number of chromosomes

They have only one set of chromosomes

During cell division, sister chromatids are joined together at which specific region?

Nucleus

Telomere

Chromatid region

Centromere (correct)

How many sets of chromosomes do gametes contain?

One set of chromosomes Signup and view all the answers

What is the result of most cell divisions, such as mitosis?

Genetically identical daughter cells Signup and view all the answers

Which statement accurately describes meiosis?

It produces sperm and egg cells. Signup and view all the answers

What happens to chromosomes as a cell prepares for division?

They condense and become visible Signup and view all the answers

What term describes the complete set of genetic information in a cell?

Genome Signup and view all the answers

What happens to a cell that does not receive a go-ahead signal at the G1 checkpoint?

It enters a nondividing state known as G0 phase. Signup and view all the answers

Which type of tumor tends to remain at the original site without invading surrounding tissues?

Benign tumor Signup and view all the answers

What role does the p53 gene play in normal cell division?

It acts as a tumor-suppressor gene to halt cell division at the G1 checkpoint. Signup and view all the answers

What distinguishes malignant tumors from benign tumors?

Malignant tumors can metastasize to form additional tumors. Signup and view all the answers

What characteristic of cancer cells allows them to escape normal cell cycle controls?

They have an abnormal cell cycle control system. Signup and view all the answers

What is the primary role of the mitotic spindle during mitosis?

To control chromosome movement. Signup and view all the answers

What initiates the assembly of spindle microtubules in animal cells?

Replication of the centrosome. Signup and view all the answers

What are kinetochores associated with?

Centromeres. Signup and view all the answers

During which phase do sister chromatids move towards opposite ends of the cell?

Anaphase. Signup and view all the answers

What structure is formed by overlapping nonkinetochore microtubules?

The elongating cell. Signup and view all the answers

At what point are chromosomes aligned at the metaphase plate?

In metaphase. Signup and view all the answers

What occurs during telophase?

Genetically identical daughter nuclei form. Signup and view all the answers

What is true about the centrosome during mitosis?

It migrates during prophase and prometaphase. Signup and view all the answers

What happens to the spindle after cytokinesis begins?

It disassembles. Signup and view all the answers

Which component will NOT be found in a mitotic spindle?

Plasma membrane. Signup and view all the answers

What process occurs during cytokinesis in animal cells?

Cleavage forming a cleavage furrow Signup and view all the answers

In plant cells, what structure is responsible for forming a new cell wall during cytokinesis?

Cell plate Signup and view all the answers

What is the asexual reproduction method utilized by prokaryotes?

Binary fission Signup and view all the answers

Which molecule is primarily responsible for regulating the frequency of cell division?

Chemical signals Signup and view all the answers

What role do external signals play in the cell cycle?

They stimulate other cells to divide. Signup and view all the answers

What is a key feature of binary fission in bacteria?

Plasma membrane pinches inward to divide the cell. Signup and view all the answers

What initiates the replication of chromosomes in prokaryotes during binary fission?

Origin of replication Signup and view all the answers

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

DNA synthesis and chromosome duplication Signup and view all the answers

What type of control is involved in the regulation of the eukaryotic cell cycle?

Both internal and external controls Signup and view all the answers

What is NOT a likely consequence of malfunction in the cell cycle control system?

Normal cell function Signup and view all the answers

In which phase of the cell cycle does the cell spend the majority of its time?

G1 phase Signup and view all the answers

Which of the following correctly sequences the phases of mitosis?

Prophase, Metaphase, Anaphase, Telophase, Cytokinesis Signup and view all the answers

How do eukaryotic cells differ from prokaryotic cells in cell division?

Eukaryotes undergo mitosis. Signup and view all the answers

What does cytokinesis specifically refer to in the context of cell division?

Division of the cytoplasm Signup and view all the answers

During which phase does the nuclear envelope break down?

Prometaphase Signup and view all the answers

Which statement best describes G2 phase in interphase?

It includes the duplication of organelles and proteins. Signup and view all the answers

Which phase of mitosis immediately follows metaphase?

Anaphase Signup and view all the answers

What occurs during the G1 phase of interphase?

Cell growth and metabolic activity Signup and view all the answers

What role do centrosomes play during mitosis?

They help separate the genetic material. Signup and view all the answers

What characterizes interphase compared to the mitotic phase?

Most of the cell cycle duration is spent here with growth. Signup and view all the answers

Study Notes

Cell Cycle

Continuity of life depends on cell reproduction, or cell division
Unicellular organisms reproduce by cell division
Multicellular organisms rely on cell division for growth and repair
Cell division can develop from a fertilized cell (zygote)

Most Cell Division Results in Genetically Identical Daughter Cells

Most cell division (mitosis) produces daughter cells with identical genetic information (DNA)
Meiosis is a special type of cell division for producing sperm and egg cells
The genome is all the DNA in a cell
- Single DNA molecule in prokaryotic cells
- Multiple DNA molecules in eukaryotic cells
- DNA in eukaryotic cells is organized into chromosomes
Every eukaryotic species has a specific number of chromosomes per cell nucleus
Somatic cells (non-reproductive cells) have two sets of chromosomes
Gametes (reproductive cells) have half the number of chromosomes as somatic cells (one set)

Distribution of Chromosomes During Eukaryotic Cell Division

Before cell division, DNA is replicated, and chromosomes condense
Each duplicated chromosome has two sister chromatids (joined copies of the original chromosome) that separate during division
The centromere is the narrow "waist" of the duplicated chromosome, where sister chromatids are most tightly attached

Stages of Mitosis

During mitosis (cell division), two sister chromatids of each duplicated chromosome separate and move into two nuclei
Once separated, the chromatids are called chromosomes

The Cell Cycle

The cell cycle is the life cycle of a cell, from formation to division
Interphase (about 90% of the cell cycle)
- G1 phase ("first gap"): cell growth
- S phase ("synthesis"): DNA replication
- G2 phase ("second gap"): preparation for mitosis
Mitotic (M) phase: mitosis and cytokinesis

Eukaryotic Cell Division

Mitosis is the division of the genetic material (DNA) within the nucleus, divided into 5 phases:
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
Cytokinesis: the division of the cytoplasm

Mitosis Stages Summarized (P.M.A.T)

Prophase: Chromosomes condense, nuclear envelope breaks down, and spindle fibers form
Metaphase: Chromosomes align in the middle of the cell
Anaphase: Sister chromatids separate and move toward opposite poles
Telophase: Two new nuclei form, chromosomes decondense, nuclear envelope reforms

The Mitotic Spindle

The spindle is a microtubule-based structure that controls chromosome movement
Mitotic spindle = centrosomes + spindle microtubules + asters
Centrosome: microtubule-organizing center
Centrosome replicates during interphase, forming two centrosomes that migrate to opposite ends of the cell
Spindle microtubules attach to kinetochores of chromosomes to move the chromosomes
Kinetochores are protein complexes associated with centromeres

Mitosis Continued

In anaphase, sister chromatids separate, move along kinetochore microtubules to opposite poles.
Nonkinetochore microtubules overlap and push against each other, elongating the cell
In telophase, genetically identical daughter nuclei form at opposite ends of the cell
Cytokinesis begins in anaphase or telophase

Cytokinesis

In animal cells, cytokinesis occurs via cleavage, forming a cleavage furrow
In plant cells, a cell plate forms
Vesicles form the cell plate, which will form the new cell wall

Cell Cycle Control System

Frequency of cell division varies depending on cell type
Cell cycle is driven by specific chemical signals (in cytoplasm)
Growth factors: proteins released by cells that stimulate cell division
Checkpoints (G1, G2, M) regulate the cell cycle (where the cell cycle stops until a go-ahead signal is received)
The G1 checkpoint is most important for most cells

Loss of Cell Cycle Controls in Cancer Cells

Cancer cells escape usual cell cycle controls
Cancer cells can make their own growth factors to grow/divide
Transformation: when a normal cell becomes a cancerous cell
Tumors: masses of abnormal cells within otherwise normal tissue
- Benign tumors stay localized
- Malignant tumors can metastasize (spread to other parts of the body)
Recent advances in cell cycle understanding have improved cancer treatment

Cancerous Cells

Characteristics of cancerous cells include variations in size and shape, a larger and darker nucleus than normal cells, and an abnormal number of chromosomes
Sarcomas: tumors in connective tissue
Carcinomas: tumors in epithelial tissue (frequently associated with lung, colon, breast, and leukemia/lymphomas)
The frequent cell division in epithelial cells makes them prone to genetic mutations
90% or more of adult cancers arise in epithelial tissues

p53 Gene

p53 is a tumor-suppressor gene
Cancer cells repeatedly undergo cell division without being halted at the G1 checkpoint when p53 is nonfunctional

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Description

This quiz focuses on the key concepts of mitosis and meiosis in multicellular organisms. It covers important topics such as chromosome sets, cell division processes, and the characteristics of somatic and cancer cells. Test your understanding of these fundamental biological processes and their implications for growth and development.