chromosome

American  

[kroh-muh-sohm] / ˈkroʊ məˌsoʊm /

noun

Genetics.

• chromosomes
  plural

1. any of several threadlike bodies, consisting of chromatin, that carry the genes in a linear order: the human species has 23 pairs, designated 1 to 22 in order of decreasing size and X and Y for the sex-determining chromosomes.

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chromosome British  

/ ˈkrəʊməˌsəʊm /

noun

1. any of the microscopic rod-shaped structures that appear in a cell nucleus during cell division, consisting of nucleoprotein arranged into units (genes) that are responsible for the transmission of hereditary characteristics See also homologous chromosomes

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chromosome Scientific  

/ krō′mə-sōm′ /

1. A structure in all living cells that consists of a single molecule of DNA bonded to various proteins and that carries the genes determining heredity. In all eukaryotic cells, the chromosomes occur as threadlike strands in the nucleus. During cell reproduction, these strands coil up and condense into much thicker structures that are easily viewed under a microscope. Chromosomes occur in pairs in all of the cells of eukaryotes except the reproductive cells, which have one of each chromosome, and some red blood cells (such as those of mammals) that expel their nuclei. In bacterial cells and other prokaryotes, which have no nucleus, the chromosome is a circular strand of DNA located in the cytoplasm.

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Other Word Forms

Derived Forms

• chromosomal
  adjective
• interchromosomal
  adjective
• nonchromosomal
  adjective
• chromosomally
  adverb
• interchromosomally
  adverb

Inflected Forms

Nouns

• chromosomes
  plural

Etymology

Origin of chromosome

First recorded in 1885–90; chromo- + -some ³

Compare meaning

How does chromosome compare to similar and commonly confused words? Explore the most common comparisons:

• chromosome vs. chromatid
• chromatin vs. chromosome
• plasmid vs. chromosome

Explanation

A chromosome is a strand of DNA that is encoded with genes. In most cells, humans have 22 pairs of these chromosomes plus the two sex chromosomes (XX in females and XY in males) for a total of 46. The word chromosome was originally coined in German from the Greek words khroma, meaning "color," and soma meaning "body." In the late 1800s, a scientist, Wilhelm von Waldeyer-Hartz, gave chromosomes their name because chromosomes easily accept dye and take on patterns of light and dark when exposed to different stains that help identify the different chromosomes.

Example Sentences

See Examples For:

chromosome chromosomes

The team found that differences in chromosome numbers among animal groups can arise in two main ways.

From Science Daily ● Aug. 25, 2026

The Year 8 student from Western Australia has Down Syndrome – a genetic condition caused by an extra copy of chromosome 21 which leads to physical and intellectual disabilities.

From BBC ● Aug. 12, 2026

Down's syndrome is when you're born with an extra chromosome - and people with the condition are likely to have some level of learning disability.

From BBC ● Jul. 26, 2026

The fact that Neanderthal DNA is rare on the X chromosome does not, in itself, allow us to reconstruct Palaeolithic social organization or the sexual preferences of these populations.

From Science Daily ● Jul. 7, 2026

At this time the chromosomes do not split, but one whole chromosome of each pair goes into each daughter cell.

From "Silent Spring" by Rachel Carson

Telomeres are protective structures located at the ends of chromosomes.

From Science Daily ● Aug. 26, 2026

It occurs when two chromosomes join, and their genes become intermixed.

From Science Daily ● Aug. 25, 2026

A human, an octopus, and a coral may appear to have almost nothing in common, but their chromosomes still contain recognizable fragments inherited from an animal ancestor that lived more than 600 million years ago.

From Science Daily ● Aug. 25, 2026

Researchers have often assumed that differences between male and female immune systems are largely driven by the X and Y sex chromosomes.

From Science Daily ● Aug. 20, 2026

The second group consists of chemicals that act on the chromosomes, probably affecting the gene chemicals and causing the chromosomes to break up.

From "Silent Spring" by Rachel Carson