Chapter8

Cell Division

The process by which a single cell divides to produce two new daughter cells.

Binary Fission

A method of asexual reproduction in prokaryotes where one cell divides into two identical cells.

Mitosis

A process of cell division that results in two genetically identical daughter cells and is involved in growth and repair.

Meiosis

A two-stage cell division process that produces gametes with half the genetic material, essential for sexual reproduction.

Interphase

The phase of the cell cycle where the cell prepares for division, consisting of G1, S, and G2 phases.

S phase

The stage of interphase in which DNA replication occurs, resulting in the formation of sister chromatids.

Cytokinesis

The final step in cell division where the cytoplasm divides, resulting in two separate cells.

Apoptosis

Programmed cell death, a mechanism that eliminates damaged or unnecessary cells.

Proto-oncogenes

Genes that promote cell division; when mutated, they can lead to cancer.

Tumor-suppressor genes

Genes that inhibit cell division; mutations can remove this control, contributing to cancer development.

p53 gene

A tumor-suppressor gene that plays a critical role in preventing cancer by repairing damaged DNA or triggering apoptosis.

Benign Tumors

Non-cancerous cell masses that do not invade nearby tissues or spread.

Malignant Tumors

Cancerous cell masses that invade surrounding tissues and can metastasize to other parts of the body.

Chromosomes

Structures within cells that contain DNA, the genetic material.

Homologous chromosomes

Pairs of chromosomes that have the same genes but possibly different alleles.

Diploid (2n)

A cell that contains two complete sets of chromosomes, one from each parent.

Haploid (n)

A cell that contains a single set of chromosomes, typical of gametes.

Crossing-over

The process during meiosis where homologous chromosomes exchange segments, increasing genetic diversity.

Independent assortment

The random distribution of homologous chromosomes during meiosis, leading to genetic variation.

Nondisjunction

The failure of homologous chromosomes to separate properly during cell division, leading to abnormal chromosome numbers.

Karyotype

A visual representation of the complete set of chromosomes in an individual, used for genetic analysis.

Trisomy 21

A genetic disorder caused by the presence of an extra copy of chromosome 21, also known as Down syndrome.