Unit 4 cell cycle, mitosis and meiosis

What are gametes?

Gametes are reproductive cells (ova and sperm) that contain 23 different chromosomes, making them haploid (n).

What are somatic cells?

Somatic cells are all body cells except those involved in meiosis, containing 46 chromosomes (diploid, 2n).

What is a homologous chromosome?

Homologous chromosomes are pairs of chromosomes (one from each parent) that are similar in length and gene position.

What is a gene?

A gene is a unit of heredity, a region of DNA that contains information for synthesizing a protein.

What are alleles?

Alleles are different versions of a gene that can produce variations in traits, such as eye color.

What is the cell cycle?

The cell cycle is the series of events that cells go through as they grow and divide, consisting of interphase and the mitotic phase.

What are the phases of interphase?

The phases of interphase are G1 (growth), S (DNA synthesis), and G2 (preparation for mitosis).

What happens during the G1 phase?

During the G1 phase, the cell grows, metabolizes, and begins centrosome replication.

What occurs during the S phase?

In the S phase, chromosomes replicate to form sister chromatids, which are still in the form of chromatin.

What happens in the G2 phase?

In the G2 phase, the cell continues to grow, produces proteins for cell division, and completes centrosome replication.

What is mitosis?

Mitosis is the process of nuclear division that results in two genetically identical diploid cells.

What are the four phases of mitosis?

The four phases of mitosis are prophase, metaphase, anaphase, and telophase.

What occurs during prophase?

During prophase, chromosomes condense, the nuclear envelope breaks down, and the spindle apparatus forms.

What happens during metaphase?

In metaphase, replicated chromosomes line up along the cell equator.

What occurs during anaphase?

In anaphase, spindle microtubules pull sister chromatids apart, moving them to opposite poles.

What happens during telophase?

During telophase, chromosomes uncoil, the nuclear envelope reappears, and cytokinesis begins.

What is meiosis?

Meiosis is a type of cell division that produces four genetically unique haploid gametes from one diploid cell.

What is the difference between meiosis I and meiosis II?

Meiosis I is a reduction division that halves the chromosome number, while meiosis II resembles mitosis and separates sister chromatids.

What occurs during prophase I of meiosis?

In prophase I, homologous chromosomes pair up to form tetrads.

What happens during metaphase I?

In metaphase I, tetrads line up along the cell equator.

What occurs during anaphase I?

In anaphase I, homologous chromosomes are pulled to opposite poles, while sister chromatids remain together.

What is the result of meiosis I?

Meiosis I results in two haploid cells, each with 23 chromosomes.

What happens during meiosis II?

Meiosis II separates sister chromatids, resulting in four haploid gametes.

What is the significance of meiosis?

Meiosis is essential for producing haploid gametes for sexual reproduction, ensuring genetic diversity.

What is a zygote?

A zygote is a fertilized egg formed by the fusion of two haploid gametes, resulting in a diploid cell (2n).

What are autosomal chromosomes?

Autosomal chromosomes are chromosomes 1 to 22 that contain genes for somatic characteristics.

What are sex chromosomes?

Sex chromosomes are the 23rd pair of chromosomes that determine biological sex (XX for female, XY for male).