Biology Flashcards: Cell Division

A comprehensive set of 50 question-and-answer flashcards covering key topics in cell division, including mitosis, meiosis, cell cycle phases and regulation, and biological reproduction.

What is mitosis?

Mitosis is the process of cell division that results in two identical daughter cells, each with the same chromosome number as the parent cell.

What are the main purposes of mitosis?

The main purposes are growth, tissue repair, and asexual reproduction.

What are the stages of mitosis?

The stages of mitosis are prophase, metaphase, anaphase, telophase, and cytokinesis.

During which phase do chromosomes condense?

Chromosomes condense during prophase.

What occurs during metaphase?

Chromosomes align at the equatorial plane of the cell, and spindle fibers attach to their centromeres.

What happens during anaphase?

Sister chromatids are pulled apart to opposite poles of the cell.

Describe what occurs in telophase.

Chromosomes decondense, nuclear envelopes reform, and the cell prepares to split.

What is cytokinesis?

Cytokinesis is the division of the cytoplasm, resulting in two separate daughter cells.

How does mitosis differ in plant and animal cells?

In plant cells, a cell plate forms during cytokinesis, while in animal cells, the membrane pinches inward.

What role do spindle fibers play in mitosis?

Spindle fibers assist in pulling apart sister chromatids during anaphase.

What is meiosis?

Meiosis is a type of cell division that reduces the chromosome number by half, creating four genetically diverse gametes.

What are the stages of meiosis?

The stages of meiosis are Meiosis I (prophase I, metaphase I, anaphase I, telophase I) and Meiosis II (prophase II, metaphase II, anaphase II, telophase II).

What is the significance of meiosis?

Meiosis ensures genetic diversity through recombination and independent assortment of chromosomes.

What occurs during prophase I of meiosis?

Chromosomes condense, homologous chromosomes pair up in a process called synapsis, and crossing over occurs.

What is crossing over?

Crossing over is the exchange of genetic material between homologous chromosomes during prophase I.

How many daughter cells are produced by meiosis?

Meiosis produces four daughter cells.

What happens during anaphase I?

Homologous chromosomes separate and are pulled to opposite poles of the cell.

Describe telophase I.

Nuclear membranes may reform, and the cell undergoes cytokinesis, resulting in two haploid cells.

What is the difference between meiosis I and meiosis II?

Meiosis I separates homologous chromosomes, while meiosis II separates sister chromatids.

What is produced at the end of meiosis II?

At the end of meiosis II, there are four haploid gametes.

What is cellular reproduction?

Cellular reproduction is the process by which cells divide to produce new cells, either through mitosis or meiosis.

Differentiate between asexual and sexual reproduction.

Asexual reproduction involves a single parent and produces identical offspring, while sexual reproduction involves two parents and produces genetically diverse offspring.

What type of cells undergo mitosis?

Somatic (body) cells undergo mitosis.

What type of cells undergo meiosis?

Germ cells undergo meiosis to produce gametes (sperm and eggs).

What is a diploid cell?

A diploid cell contains two sets of chromosomes ($2n$), one from each parent.

What is a haploid cell?

A haploid cell contains one set of chromosomes ($n$), typical of gametes.

Explain the term "genetic diversity."

Genetic diversity refers to the variety of genes within a population, which is increased through sexual reproduction.

What is the role of enzymes in DNA replication during cell division?

Enzymes like DNA polymerase are crucial for replicating DNA accurately during cell division.

What mechanism ensures the accuracy of DNA replication?

Proofreading by DNA polymerase and mismatch repair mechanisms help maintain accuracy in DNA replication.

Describe the G1 phase of the cell cycle.

During G1 phase, the cell grows and carries out normal functions, preparing for DNA replication.

What happens during the S phase of the cell cycle?

DNA is replicated during the S phase, resulting in two sets of chromosomes.

What occurs in the G2 phase?

The cell continues to grow and prepares for mitosis, producing proteins and organelles required for division.

What is the role of checkpoints in the cell cycle?

Checkpoints ensure that cells are ready to proceed through the cell cycle and help prevent errors in cell division.

What is cancer in relation to cell division?

Cancer arises from uncontrolled cell division due to disruptions in regulatory genes and checkpoints in the cell cycle.

What is apoptosis?

Apoptosis is programmed cell death that eliminates damaged or unnecessary cells from the organism.

How are proteins involved in the regulation of the cell cycle?

Cyclins and cyclin-dependent kinases (CDKs) regulate progression through the cell cycle by activating enzymes at checkpoints.

Define "chromatid."

A chromatid is one-half of a duplicated chromosome, joined at the centromere until they are separated during anaphase.

What are homologous chromosomes?

Homologous chromosomes are pairs of chromosomes, one from each parent, that have the same genes but may have different alleles.

Illustrate the difference in chromosome alignment during meiosis vs. mitosis.

In meiosis, homologous chromosomes align in pairs during metaphase I, while in mitosis, individual chromosomes align during metaphase.

What is independent assortment?

Independent assortment is the random distribution of maternal and paternal chromosomes during gamete formation in meiosis, contributing to genetic diversity.

Why is meiosis essential for sexual reproduction?

Meiosis produces gametes with half the chromosome number, allowing for genetic diversity and restoration of the diploid number upon fertilization.

What role does the nucleus play during mitosis?

The nucleus contains the genetic material that is divided and distributed to daughter cells during mitosis.

Explain the purpose of cell division.

Cell division allows organisms to grow, repair tissues, replace dead or damaged cells, and asexually reproduce.

What is the function of centrioles during cell division?

Centrioles help organize spindle fibers during mitosis and meiosis, facilitating the separation of chromosomes.

Compare the end results of mitosis and meiosis.

Mitosis results in two identical diploid cells, while meiosis results in four genetically diverse haploid cells.

How does environmental stress affect cell division?

Environmental stress can induce DNA damage responses or apoptosis, affecting normal cell cycle progression.

What is the significance of the centromere?

The centromere is the region where sister chromatids are joined and where spindle fibers attach during cell division.

Define "fertilization."

Fertilization is the fusion of male and female gametes, resulting in the formation of a zygote and restoration of the diploid number.

What role do hormones play in reproduction?

Hormones regulate the processes of growth, gamete production, and changes in the reproductive system associated with sexual maturation.

How do mutations in DNA affect cell division?

Mutations can lead to uncontrolled cell division, which may result in cancer or inherited genetic disorders.