Cell Cycle

Genome

Entire DNA content of a cell.

Prokaryotic Genome

Composed of single, circular double-stranded DNA located in the nucleoid region.

Eukaryotic Genome

Organized in multiple linear, double-stranded molecules, composed of DNA and proteins that form chromosomes.

Diploid

A cell with two matched sets of chromosomes, represented as 2n.

Haploid

A cell with one set of chromosomes, represented as n.

Chromosomes

Structures that contain DNA organized in pairs in diploid organisms.

Homologous Chromosomes

Chromosomes that are the same length, contain the same gene loci, and are similar in structure and function.

Allelic Variation

Differences in gene sequence that may occur between homologous chromosomes.

Gene

Functional unit of a chromosome that codes for specific proteins.

Trait

Different forms of characteristics determined by genes.

Genetic Variation

Differences in gene versions from each parent.

Gametes

Haploid sex cells that have half the chromosome number.

Sister Chromatids

Identical copies of a chromosome connected at the centromere after DNA replication.

Centrosome

Microtubule-organizing center that forms the spindle for chromosome movement in mitosis.

Cell Cycle

The orderly sequence of events in a cell's life encompassing growth and division.

Interphase

The phase where normal cell processes occur and preparations for division are made.

G1 Phase

First gap phase where the cell increases biosynthesis and accumulates necessary components for DNA replication.

S Phase

Synthesis phase where DNA replication occurs, forming sister chromatids.

G2 Phase

Second gap phase where the cell replenishes energy and synthesizes proteins for chromosome manipulation.

G0 Phase

Quiescent, non-dividing stage where some cells exit the cell cycle.

Mitosis

Division of the nucleus that results in two genetically identical daughter cells.

Cytokinesis

Division of the cytoplasm resulting in two daughter cells post-mitosis.

Prophase

First stage of mitosis where chromosomes condense and the nuclear envelope breaks down.

Anaphase

Phase of mitosis where sister chromatids are separated and move toward opposite poles.

Telophase

Final stage of mitosis where chromosomes decondense and nuclear envelopes reform.

Checkpoints

Control mechanisms in the cell cycle that ensure accuracy in division.

G1 Checkpoint

Restriction point that checks nutrient availability, cell size, and DNA damage before S phase.

G2 Checkpoint

Checkpoint that ensures DNA replication is complete and DNA is undamaged before entering mitosis.

M Checkpoint

Spindle checkpoint that ensures all sister chromatids are correctly attached to spindle fibers before anaphase.

Mutation

Permanent change in DNA nucleotide sequence, which can lead to cancer.

Proto-oncogene

A gene that codes for positive regulators of the cell cycle; becomes an oncogene when mutated.

Oncogene

A mutated proto-oncogene that causes abnormal cell growth and can lead to cancer.

Tumor Suppressor Gene

Genes coding for proteins that prevent uncontrolled cell division.

p53

Key tumor suppressor protein that halts the cell cycle to allow for DNA repair or trigger apoptosis.

Binary Fission

Type of asexual reproduction in prokaryotes producing identical daughter cells.

FtsZ Protein

Key protein in prokaryotic cytokinesis that forms a ring at the cell midpoint.

Eukaryotic Cell Division

Process that includes mitosis and cytokinesis to produce daughter cells.

Sexual Reproduction

Union of gametes from two individuals, resulting in offspring with genetic variation.

Meiosis

Nuclear division reducing chromosome number from diploid to haploid, producing gametes.

Crossing Over

Exchange of segments between non-sister chromatids during Prophase I of meiosis.

Independent Assortment

Random orientation of homologous chromosomes during Metaphase I, contributing to genetic variation.

Aneuploidy

Abnormal number of chromosomes resulting from nondisjunction during cell division.

X Inactivation

Random condensation of one X chromosome into a Barr body in female cells for dosage compensation.

Polyploidy

Condition of having more than two sets of chromosomes, often seen in plants.

Karyotype

Visual profile of chromosomes that can detect abnormalities in chromosome number and structure.

Cleavage Furrow

Indentation that begins the process of cytokinesis in animal cells.

Cell Plate

Structure that forms the new cell wall during cytokinesis in plant cells.

Germ Cell

Diploid cell that undergoes meiosis to form gametes.

Apoptosis

Programmed cell death that can be triggered if DNA damage is irreparable.

Nondisjunction

Failure of chromosomes or sister chromatids to separate properly during meiosis.