Bio 140.1 Genetics Lab: Mitosis and Meiosis

Questions and Answers

What is the main purpose of mitosis in multicellular organisms?

Reduction of chromosome number

Formation of genetically identical somatic cells (correct)

Production of gametes

Cellular growth without division

What is the position called where chromosomes align during metaphase?

Tetrad

Cleavage furrow

Centromere

Metaphase plate (correct)

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

Anaphase

Interphase (correct)

Prophase

Metaphase

What is karyokinesis?

Replication of the nucleus Signup and view all the answers

During which phase do chromatids separate and move to opposite poles?

Anaphase Signup and view all the answers

What forms during telophase and serves to create two daughter cells?

Cleavage furrow Signup and view all the answers

Which of the following statements regarding meiosis is true?

It results in cells with half the chromosome number of the parent cell. Signup and view all the answers

What are the final products of meiosis?

Four haploid gametes Signup and view all the answers

What major event occurs during prophase of mitosis?

Chromatin condenses into distinct chromosomes Signup and view all the answers

What significant event occurs during prophase I of meiosis?

Tetrads form and crossing over occurs Signup and view all the answers

What type of cells primarily undergo mitosis?

Somatic cells Signup and view all the answers

In which phase of meiosis do homologous chromosomes line up at the metaphase plate?

Metaphase I Signup and view all the answers

In which region of a plant is the highest percentage of cells undergoing mitosis found?

Root tips Signup and view all the answers

What occurs during telophase II of meiosis?

Formation of haploid cells Signup and view all the answers

What is the role of the spindle apparatus during mitosis?

To separate sister chromatids Signup and view all the answers

What is the role of spindle fibers during mitosis?

To separate chromatids to opposite poles Signup and view all the answers

What is the primary function of the S (synthesis) phase in the cell cycle?

DNA undergoes replication to produce sister chromatids Signup and view all the answers

What change occurs to chromosomes during prophase?

Chromosomes condense and become shorter and thicker Signup and view all the answers

In which phase of the cell cycle do chromatids become attached at the centromere?

Metaphase Signup and view all the answers

What marks the end of prophase in the cell cycle?

Nucleoli dissolve and nuclear membrane disappears Signup and view all the answers

What is the appearance of nuclei during interphase?

Prominent darkly stained nucleoli with uncondensed chromosomes Signup and view all the answers

What initiates the dynamic processes of mitosis?

Cell commitment to DNA replication during interphase Signup and view all the answers

What is a key characteristic of chromosomes during metaphase?

Chromosomes are short and thicker with visible spindle attachment Signup and view all the answers

Which event occurs continuously throughout the cell cycle?

Cells undergo specialization Signup and view all the answers

What is the main purpose of spermatogenesis?

To transform diploid spermatogonia into four haploid sperm cells Signup and view all the answers

During which phase do sister chromatids exchange genetic material in spermatogenesis?

Interphase before Meiosis I Signup and view all the answers

How many sperm cells are produced from one diploid spermatogonium?

Four sperm cells Signup and view all the answers

What type of cells are formed through oogenesis?

Haploid ova from diploid primary oocytes Signup and view all the answers

What is a notable difference between spermatogenesis and oogenesis?

Spermatogenesis results in more cells compared to oogenesis Signup and view all the answers

What happens to the daughter cells after Meiosis I in spermatogenesis?

They go through a second meiotic division to yield four cells Signup and view all the answers

What occurs during the S phase of the cell cycle?

Chromosomes undergo replication to produce sister chromatids. Signup and view all the answers

What is the main event that occurs during Prophase I?

Synapsis of homologous chromosomes occurs. Signup and view all the answers

At what stage does a primary oocyte exist in the female ovaries?

Before Meiosis I Signup and view all the answers

Which of the following statements about spermatogenesis is accurate?

It starts producing sperm cells at puberty and continues throughout life Signup and view all the answers

During which phase do homologous chromosomes move to opposite poles?

Anaphase I Signup and view all the answers

What significant process occurs during Prophase I that alters genetic diversity?

Crossing over occurs between chromatids. Signup and view all the answers

What is the result of Telophase I in meiosis?

Nuclei re-form with haploid chromosomes. Signup and view all the answers

What is unique about Interphase II of meiosis?

No replication of genetic material takes place. Signup and view all the answers

What happens during Anaphase II of meiosis?

Sister chromatids move toward opposite poles. Signup and view all the answers

Which phase of meiosis is characterized by chromosomes being visible again?

Prophase II Signup and view all the answers

Study Notes

Mitosis

Cells originate from pre-existing cells through karyokinesis and cytokinesis.
Mitosis produces genetically identical somatic cells (2n).
Key processes: growth, asexual reproduction, regeneration, and body part repair.
Best observed in rapidly growing cells, such as whitefish blastula and onion root tips.
Interphase occurs before mitosis with distinct nucleus and chromatin network.
Prophase: Chromatin condenses into chromosomes, nuclear envelope dissolves, spindle apparatus appears.
Metaphase: Chromosomes align at the metaphase plate, centromeres attach to spindle fibers.
Anaphase: Chromatids separate and are pulled to opposite poles, redefining them as chromosomes.
Telophase: New nuclear envelope forms, chromosomes uncoil into chromatin, and cytokinesis begins through cleavage furrow.

Meiosis

Comprises two nuclear divisions: Meiosis I and Meiosis II.
Produces four haploid gametes (1n), promoting genetic variation through crossing over.
Preceded by interphase which includes DNA replication.
Prophase I involves homologous chromosomes pairing to form tetrads, allowing crossing over.
Metaphase I: Tetrads align at the metaphase plate.
Anaphase I: Homologous chromosomes are pulled to opposite poles.
Telophase I prepares cells for Meiosis II, resulting in two cells with half the original chromosome number.

Spermatogenesis

Meiotic process that produces sperm cells in male testes from diploid spermatogonia.
Each diploid spermatogonium transforms into four haploid sperm cells.
Interphase involves chromosome replication before Meiosis I.
Resulting sperm cells contain unique sets of 23 chromosomes.
Occurs continuously after puberty, producing millions of sperm daily.

Oogenesis

Meiotic process resulting in the formation of ova (egg cells) from primary oocytes in female ovaries.
Different from spermatogenesis due to metabolic activity and distinct timing of maturation.
Primary oocytes undergo meiosis to produce haploid cells, with specific regulatory events managing DNA replication.
Oogenesis is a more lengthy and complex process than spermatogenesis.

Stages of Meiosis

Interphase II: Nuclei uncoil; no DNA replication occurs.
Prophase II: Chromosomes condense and become visible.
Metaphase II: Duplicated chromosomes line up at the equatorial plate.
Anaphase II: Centromeres separate, allowing chromatids to move to opposite poles.
Telophase II: Nuclei reform, each with a haploid number of chromosomes.

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Description

This quiz focuses on Exercise 2 of Bio 140.1, which explores the processes of mitosis and meiosis in cell division. Understand the key steps involved in karyokinesis and cytokinesis and their significance in cellular reproduction. Prepare to test your knowledge on these fundamental concepts in genetics.