BIO 101 Lecture 04: Cell Division

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Questions and Answers

What are the two mechanisms by which cytokinesis occurs?

Cleavage and cell plate formation (correct)

Mitosis and meiosis

Fission and fragmentation

Binary fission and budding

What is the significance of mitosis in multicellular organisms?

It leads to the production of gametes.

It causes variations in genetic material.

It reduces the chromosome number in daughter cells.

It is responsible for the development from a single-cell zygote. (correct)

What outcome is not a result of mitosis?

Chromosomes in unduplicated form in daughter cells

Each daughter cell having double the chromosome number (correct)

Formation of two daughter nuclei

Remodeling of damaged tissues

Which statement about HeLa cells is true?

They are derived from tumor cells of Henrietta Lacks. Signup and view all the answers

What does the result of mitosis typically ensure for daughter cells?

They remain genetically identical to the parent cell. Signup and view all the answers

What is the primary purpose of the cell cycle?

To produce two new daughter cells Signup and view all the answers

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

S phase Signup and view all the answers

Which stage of mitosis involves the alignment of chromosomes at the spindle equator?

Metaphase Signup and view all the answers

What happens to the chromosomes during anaphase?

Sister chromatids are pulled apart Signup and view all the answers

What event characterizes the beginning of telophase?

De-condensation of chromosomes Signup and view all the answers

What is the function of spindle fibers during mitosis?

To separate sister chromatids Signup and view all the answers

Which phase follows the completion of mitosis?

Cytokinesis Signup and view all the answers

What occurs during the G1 phase of the cell cycle?

Cell mass increases and organelles are produced Signup and view all the answers

What is the primary outcome of meiosis?

Production of haploid gametes Signup and view all the answers

During which phase of meiosis do homologous chromosomes exchange segments?

Prophase I Signup and view all the answers

What occurs during Metaphase I of meiosis?

Homologous chromosomes align in the center of the cell Signup and view all the answers

How many haploid nuclei are produced at the end of meiosis?

Four Signup and view all the answers

What is true about the DNA content between Meiosis I and Meiosis II?

DNA remains unchanged Signup and view all the answers

Which of the following accurately describes anaphase I?

Homologous chromosomes segregate to opposite poles Signup and view all the answers

What roles do homologous chromosomes play in sexual reproduction?

They ensure genetic diversity through crossing over Signup and view all the answers

What happens to the spindle apparatus during Telophase I?

It breaks down completely Signup and view all the answers

What is produced as a result of meiosis?

Four haploid cells Signup and view all the answers

During which phase of meiosis do sister chromatids become independent chromosomes?

Anaphase II Signup and view all the answers

What happens during Telophase II?

Nuclear envelopes form around each set of chromosomes Signup and view all the answers

Which of the following describes the significance of meiosis?

It allows for greater genetic variation Signup and view all the answers

How does meiosis differ from mitosis in terms of genetic outcome?

Mitosis produces cloned cells while meiosis does not Signup and view all the answers

What role do recombinations play in meiosis?

They provide for genetic variation necessary for evolution Signup and view all the answers

What is a characteristic feature observed during metaphase II?

Chromosomes line up at the spindle equator Signup and view all the answers

What is the primary purpose of meiosis in sexual reproduction?

To generate gametes with half the chromosome number Signup and view all the answers

Study Notes

Cell Cycle

The cell cycle consists of ordered events that enable cell growth and division, resulting in two daughter cells.
Cell division is a critical process that occurs within the cell cycle, where a parent cell divides into multiple daughter cells.

Phases of the Cell Cycle

G1 Phase: Longest phase characterized by cell growth, increased mass, and doubling of cytoplasmic components.
S Phase: DNA synthesis phase, where DNA is replicated.
G2 Phase: Interval following DNA replication before mitosis begins.

Mitosis Overview

Mitosis is the nuclear division process typically followed by cytoplasmic division.
Mitosis comprises four stages: Prophase, Metaphase, Anaphase, and Telophase.

Prophase

Chunks of duplicated chromosomes condense and microtubules are assembled.
The nuclear envelope begins to break down while spindle formation occurs.
Spindle microtubules attach to sister chromatids.

Metaphase

Chromosomes align at the spindle equator.
Chromosomes are in their most condensed form.

Anaphase

Each paired chromosome splits into two sister chromatids, now referred to as daughter chromosomes.
Daughter chromosomes move to opposite poles due to spindle fiber contraction.
Each pole ends the phase with a complete set of chromosomes.

Telophase

Chromosomes begin to de-condense, and nuclear membranes develop around each set of chromosomes.

Cytokinesis

Cytoplasmic division occurs, typically between late Anaphase and end of Telophase.
Two mechanisms: Cleavage in animals and cell plate formation in plants.

Results of Mitosis

Two daughter nuclei are formed, each containing the same chromosome number as the parent cell.
Chromosomes in daughter cells are in an unduplicated state.

Significance of Mitosis

Essential for growth and development of multicellular organisms.
Transforms a single-cell zygote into a fully developed adult.
Maintains consistent chromosome numbers across daughter cells.
Repairs damaged tissues, exemplified by skin cell regeneration.

HeLa Cells

Derived from Henrietta Lacks, HeLa cells are a line of human cancer cells that can grow in culture.
Valuable for medical research, contributing to the polio vaccine and studies on the effects of zero gravity.
Used in cloning, in vitro fertilization, and gene mapping.

Meiosis Overview

Meiosis involves two successive nuclear divisions (Meiosis I and Meiosis II) without DNA duplication between divisions.
Results in four haploid nuclei from a diploid parent cell.

Meiosis I and II

Meiosis I: Homologous chromosomes segregate, resulting in two haploid cells.
- Prophase I includes homologous chromosome pairing and segment exchange.
- Metaphase I aligns chromosomes, with sister chromatids orienting toward opposite poles.
- Anaphase I separates homologous chromosomes while sister chromatids stay attached.
Meiosis II: Similar to mitosis, where sister chromatids separate to form four haploid cells.

Results of Meiosis

Four unique haploid cells are produced, each differing from the parent and one another.

Significance of Meiosis

Generates four haploid gametes for sexual reproduction.
Facilitates genetic variation through recombination, crucial for evolution.
Reduces chromosome number by half, allowing for successful zygote formation during fertilization.

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Description

Explore the essential concepts of the cell cycle and cell division in this introductory biology quiz. Learn about the phases involved in cell growth and the processes leading to the formation of daughter cells. Perfect for students enrolled in BIO 101.