Cell Cycle Overview

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the haploid number of chromosomes present in each daughter cell after Telophase I?

23 chromosomes (correct)

46 chromosomes

24 chromosomes

22 chromosomes

What occurs during Anaphase I of meiosis?

Homologous pairs of chromosomes migrate to opposing poles (correct)

Sister chromatids separate and migrate to poles

Nuclei reform and cytokinesis occurs

Chromosomes recombine with sister chromatids

Which statement about Meiosis II is correct?

It is preceded by an S phase for DNA synthesis

It results in no cells being formed

It produces a total of four cells from one diploid germ cell (correct)

Chromosomes do not line up at the equator

What feature is characteristic of chromosomes during Telophase I of meiosis?

Each chromosome is still composed of two chromatids (A) Signup and view all the answers

Which statement about the kinetochores during Meiosis II is true?

Kinetochores attach to spindle fibers during metaphase II (A) Signup and view all the answers

What is the purpose of the G1 phase in the cell cycle?

Cell size is increased, and macromolecules for DNA synthesis are made. (D) Signup and view all the answers

During which phase of the cell cycle does DNA replication take place?

S phase (B) Signup and view all the answers

What key event occurs during the G2 phase of interphase?

Synthesis of RNA and proteins for mitosis preparation. (C) Signup and view all the answers

What is karyokinesis?

The division of the nucleus during mitosis (A) Signup and view all the answers

Which statement accurately describes meiosis?

It consists of two successive divisions and reduces chromosome number. (C) Signup and view all the answers

What defines the stage of metaphase in mitosis?

Chromosomes line up at the equator of the mitotic spindle. (A) Signup and view all the answers

Which of the following components are synthesized during the G1 phase?

Macromolecules essential for DNA duplication (C) Signup and view all the answers

What happens to the amount of DNA in autosomal cells during the S phase?

It doubles in preparation for cell division. (C) Signup and view all the answers

Which structure disappears during prophase?

Nucleolus and nuclear envelope (D) Signup and view all the answers

What is the duration of the mitotic phase compared to interphase?

Mitotic phase is shorter than interphase. (D) Signup and view all the answers

What is the result of cytokinesis during telophase?

Complete division of the cytoplasm (C) Signup and view all the answers

What is a key outcome of meiosis?

Genetic recombination and variability (C) Signup and view all the answers

During which stage of meiosis does crossing over occur?

Prophase I (D) Signup and view all the answers

What happens to the chromosome number during meiosis I?

It reduces from diploid to haploid. (B) Signup and view all the answers

What is the significance of the centromere in chromosomes?

It serves as the attachment point for spindle fibers during division. (B) Signup and view all the answers

Study Notes

Cell Cycle

The cell cycle is a series of events in a cell preparing it to divide into two daughter cells.
Cell division is how pre-existing cells multiply.
Cell multiplication is crucial for embryonic development.
Cells require division after birth for growth and replacing dead cells.
Daughter cells must have identical chromosome number and genetic content as the parent cell (mitosis).
Meiosis is composed of two divisions, reducing the chromosome number to half the normal amount. Genetic information in gametes produced isn't identical.

The Cell Cycle: Major Events

Interphase: A long period of time before cell division. It includes:
- G1 phase (Gap 1): Cell growth, synthesis of macromolecules (RNA, regulatory proteins, enzymes) needed for DNA replication. Cell volume returns to normal. Centrioles begin to duplicate.
- S phase (Synthesis): DNA replication occurs, doubling the amount of DNA in the cell (autosomal cells go from 2n to 4n).
- G2 phase (Gap 2): The final stage of cell growth; cell prepares for mitosis by producing proteins and energy stores.
Mitosis: A shorter period where the nucleus divides first, then the cytoplasm, creating two daughter cells.
- This process is also known as karyokinesis, followed by cytokinesis.
- Mitosis contains 4 stages: prophase, metaphase, anaphase, and telophase.
Cells that stop dividing reside in the stable phase (G0).

Mitosis Stages

Prophase: Chromosomes condense and become visible. Centrioles move to opposite poles, the nuclear envelope breaks down.
Metaphase: Chromosomes align along the equator of the cell.
Anaphase: Sister chromatids separate and move to opposite poles.
Telophase: Chromosomes reach poles, decondense, and the nuclear envelope reforms. Cytoplasm divides (cytokinesis), creating two daughter cells.

Meiosis

A special cell division creating gametes (sperm and egg). It reduces the chromosome number from diploid (2n) to haploid (1n).
Two rounds of divisions (Meiosis I and Meiosis II).
- Meiosis I (Reductional division): Homologous chromosomes separate. Diploid cells become haploid.
  - Lasts a long time as homologous chromosomes pair up for crossing over. Chiasmata (crossing over sites) appear during prophase I, exchanging genetic material.
  - Prophase I: Long process, homologous chromosomes pair up and exchange genetic material (crossing-over).
  - Metaphase I: Homologous chromosome pairs line up at the metaphase plate.
  - Anaphase I: Homologous chromosomes separate and are pulled to opposite poles.
  - Telophase I: Chromosomes reach the poles, the nuclear envelope may reform, and cytokinesis may occur, splitting the cell into two.
- Meiosis II (Equational division): Similar to mitosis. Sister chromatids separate, creating four haploid daughter cells. Each daughter cell contains a haploid number of chromosomes and has unique genetic content.
Resulting in four daughter cells containing unique genetic material.

Key Concepts

Chromosomes and Chromatids: Chromosomes are condensed DNA, visible during mitosis and meiosis. Sister chromatids are identical copies of a chromosome, joined at the centromere.
Genetic Variation: Meiosis through crossing-over in prophase I, and random assortment of chromosomes during metaphase I, leads to genetic variation in gametes.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the critical phases of the cell cycle including interphase, mitosis, and meiosis. Understand the importance of cell division for growth and development. This quiz will test your knowledge of each phase and its role in cellular processes.