Biology Cell Cycle and Mitosis

Questions and Answers

Explain the cell cycle.

The cell cycle is a series of events that takes place from one cell division to the next. It involves interphase, mitosis, and the division of the cell.

Define mitosis and explain why it is important.

Mitosis is the process in which the nucleus divides to form two identical nuclei. It allows growth and replaces worn out or damaged cells.

List and explain each step of mitosis.

Prophase, Metaphase, Anaphase, Telophase.

What happens during prophase?

The chromatid pairs are now visible and the spindle is beginning to form. Signup and view all the answers

What happens during metaphase?

The chromatid pairs are lined up in the center of the cell. Signup and view all the answers

What happens during anaphase?

The chromatids separate. Signup and view all the answers

What happens during telophase?

In the final step, the cytoplasm is beginning to separate. Signup and view all the answers

Define 'chromosome' and explain its role in mitosis.

A chromosome is a structure in the nucleus that contains hereditary material. Signup and view all the answers

Define 'sexual reproduction'.

When two sex cells come together. This type of reproduction involves two organisms. Signup and view all the answers

Give two examples of asexual reproduction and explain each one.

Budding and regeneration. Signup and view all the answers

What is a sperm?

A sex cell formed in the male reproductive organ. Signup and view all the answers

What is an egg?

A sex cell formed in the female reproductive organ. Signup and view all the answers

Define 'fertilization'.

The joining of an egg and a sperm. Signup and view all the answers

What is a zygote?

The cell that forms from fertilization. Signup and view all the answers

Define diploid cells.

Cells that are formed from mitosis and contain 46 chromosomes; examples include body cells. Signup and view all the answers

Define haploid cells.

Cells that are formed from meiosis and contain 23 chromosomes; examples are sex cells. Signup and view all the answers

Compare and contrast diploid and haploid cells.

Diploid cells have 46 chromosomes and are body cells, while haploid cells have 23 chromosomes and are sex cells. Signup and view all the answers

Define meiosis and explain why it is important.

Meiosis produces haploid cells necessary for sexual reproduction. Signup and view all the answers

List and explain each step of meiosis I and meiosis II.

Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, Telophase II. Signup and view all the answers

Explain why there are two divisions of meiosis.

There are two divisions of meiosis to produce haploid cells, which are half the number of diploid cells. Signup and view all the answers

Define DNA.

A code that contains information for an organism's growth and function. Signup and view all the answers

Define a gene.

The instructions for making a specific protein; it is a section of DNA on a chromosome. Signup and view all the answers

Define mutation.

Any permanent change in the DNA sequence of a gene or chromosome of a cell. Signup and view all the answers

Identify the nitrogen bases of a DNA molecule.

Adenine pairs with Thymine and Cytosine pairs with Guanine. Signup and view all the answers

Study Notes

The Cell Cycle

A sequence of events from one cell division to the next.
Comprises three main stages: interphase, mitosis, and cytokinesis.

Mitosis

Defined as the process of nucleus division to create two identical nuclei.
Consists of four phases: prophase, metaphase, anaphase, and telophase.
Essential for growth, tissue repair, and asexual reproduction in certain organisms.

Phases of Mitosis

Prophase: Chromatid pairs become visible; spindle fibers begin to form.
Metaphase: Chromatid pairs align at the cell's equatorial plane.
Anaphase: Chromatids separate and move towards opposite poles of the cell.
Telophase: Cytoplasm starts to divide and the nuclear membrane re-forms.

Chromosomes

Structures in the nucleus housing hereditary material.
Each chromosome duplicates during interphase to prepare for mitosis, ensuring equal distribution into daughter cells.

Reproductive Processes

Sexual Reproduction: Involves two organisms merging their sex cells (sperm and egg).
Asexual Reproduction: New organisms arise from a single parent via mitosis.
- Budding: New organism develops from the parent and detaches once mature.
- Regeneration: Body parts regrow through mitosis and cell division.

Key Reproductive Cells

Sperm: Male sex cell produced in reproductive organs.
Egg: Female sex cell produced in reproductive organs.
Fertilization: Occurs when an egg unites with a sperm, forming a zygote.
Zygote: The initial cell resulting from fertilization.

Diploid and Haploid Cells

Diploid: Formed through mitosis; contain 46 chromosomes; examples include body cells like blood and skin.
Haploid: Formed through meiosis; contain 23 chromosomes; examples are sex cells (sperm and egg).
Key differences: Diploid cells are body cells, while haploid cells are reproductive cells.

Meiosis

A specialized cell division that produces haploid cells for sexual reproduction.
Essential for preventing chromosome overflow in offspring, ensuring genetic diversity through reduction in chromosome number.

Steps of Meiosis

Meiosis I:
- Prophase I: Duplicated chromosomes pair up with their counterparts.
- Metaphase I: Homologous chromosome pairs align at the cell center.
- Anaphase I: Chromosome pairs separate to opposite ends.
- Telophase I: Cytoplasm divides, resulting in two new cells.
Meiosis II:
- Prophase II: Chromosomes condense; spindle fibers form in each new cell.
- Metaphase II: Duplicated chromosomes line up individually at the cell center.
- Anaphase II: Centromeres split, and chromatids move to opposite ends.
- Telophase II: Cytoplasm divides, forming four haploid cells.

Importance of Two Divisions in Meiosis

Ensures the creation of haploid cells to maintain proper chromosome numbers in sexual reproduction.
Essential for genetic variation and successful reproduction.

DNA and Genes

DNA: Contains genetic instructions for an organism's development and function.
Gene: Specific sequence of DNA that provides instructions for synthesizing a particular protein.

Mutations

Refers to permanent alterations in the DNA sequence of a gene or chromosome, which can affect an organism's traits and functions.

Nitrogen Bases of DNA

Four bases: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).
Base pairing rules: Adenine pairs with Thymine and Cytosine pairs with Guanine, maintaining equal amounts in the DNA molecule.

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Description

Explore the key concepts of the cell cycle, including the stages of interphase, mitosis, and cytokinesis. This quiz will cover the phases of mitosis, the structure of chromosomes, and the importance of these processes in growth and reproduction. Test your knowledge on how cells divide and replicate!