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Longman Dictionary of Contemporary English
X chromosome
Y chromosome
▪ There is no diploid nucleus, with a complete complement of chromosomes, until we reach the two-cell stage.
▪ At this stage, when the chromatids have been separated from each other, they can again be regarded as complete chromosomes.
▪ Now that we have two complete sets of chromosomes, it is just a question of restoring order.
▪ The basic reason for such sterility is that the two parents contain different numbers of chromosomes.
▪ There must have been at least one individual who had a different number of chromosomes from his parents.
▪ Whole lengths of code, as we shall see, may occasionally be copied to completely different chromosomes.
▪ Human ALDHs are encoded at four independant loci on four different chromosomes.
▪ Some populations even have different numbers of chromosomes.
▪ They diverged to different parts of an ancestor's chromosomes, and we have each inherited them on our different chromosomes.
▪ They can have from a handful of copies to several hundred, often scattered on many different chromosomes.
▪ Abnormalities of human chromosomes following therapeutic irradiation.
▪ There are approximately 10 9 base pairs in the human chromosome set.
▪ Further work is under way to map the human gene in detail but preliminary results support the localisation to human chromosome 11.
▪ Lane 1 corresponds to a cosmid from human chromosome 6 and serves as a control.
▪ Hybridisation of the cosmid library representing a 4 fold coverage of human chromosome 21 with the exon-enriched probe.
▪ Oct-11a is located in a region of mouse chromosome 9 homologous with the long arm of human chromosome 11.
▪ The chromatids, once separated from their twins, can now be called chromosomes.
▪ Once the chromatids are separated they can be called chromosomes.
▪ A cell containing four sets of chromosomes is said to be tetraploid.
▪ It contains your chromosomes and makes you what you are.
▪ In a human being one cell contains 23 pairs of chromosomes.
▪ The basic reason for such sterility is that the two parents contain different numbers of chromosomes.
▪ First, every biologist knows that most body cells of most animals are diploid; they contain two sets of chromosomes.
▪ As we have seen, each cell of the human body save the ovum and spermatozoon normally contains 46 chromosomes.
▪ Human body cells contain chromosomes, forty-six in each cell.
▪ Our sperms or eggs each contain 23 chromosomes.
▪ Humans have 46 chromosomes.
▪ However, the genes brought in by a plasmid do not usually become a permanent part of the bacterium's own chromosome.
▪ In a human being one cell contains 23 pairs of chromosomes.
▪ In man, for instance, the genes that control gender are on the Y chromosome.
▪ Lane 1 corresponds to a cosmid from human chromosome 6 and serves as a control.
▪ Reduced to just the haploid maternal complement of chromosomes, the egg develops into a male.
▪ The cytoplasmic apparatus thus effects chromosome division.
▪ The research found that alpha rays may cause damage to cells which only becomes apparent much later when abnormal chromosomes appear.
▪ When the membrane breaks down, licensing factors from the cytoplasm gain access to the chromosomes.
The Collaborative International Dictionary

Chromosome \Chro"mo*some`\, n. [Gr. ? color + ? the body.] (Biol.) One of the minute bodies into which the chromatin of the nucleus is resolved during mitotic cell division; the idant of Weismann.

Douglas Harper's Etymology Dictionary

1889, from German Chromosom, coined 1888 by German anatomist Wilhelm von Waldeyer-Hartz (1836-1921), from Latinized form of Greek khroma "color" (see chroma) + -some (3)). So called because the structures contain a substance that stains readily with basic dyes.


n. (context biology cytology English) A structure in the cell nucleus that contains DNA, histone protein, and other structural proteins.


n. a threadlike body in the cell nucleus that carries the genes in a linear order

Chromosome (genetic algorithm)

In genetic algorithms, a chromosome (also sometimes called a genotype) is a set of parameters which define a proposed solution to the problem that the genetic algorithm is trying to solve. The set of all solutions is known as the population. The chromosome is often represented as a binary string, although a wide variety of other data structures are also used.


A chromosome (from color and body) is a packaged and organized structure containing most of the DNA of a living organism. DNA is not usually found on its own, but rather is structured in long strands which are wrapped around protein complexes called nucleosomes, which consist of proteins called histones. The DNA in chromosomes serves as the source for transcription. Most eukaryotic cells have a set of chromosomes (46 in humans) with the genetic material spread among them.

During most of the duration of the cell cycle, a chromosome consists of one long (its width to length ratio is about 1:65,000,000) double-helix DNA molecule (with associated proteins). During S phase, the chromosome gets replicated, resulting in an X-shaped structure called a metaphase chromosome. Both the original and the newly copied DNA are now called chromatids. The two "sister" chromatids are joined together at a protein junction called a centromere (forming the X-shaped structure).

Chromosomes are normally visible under a light microscope only when the cell is undergoing mitosis (cell division). Even then, the full chromosome containing both joined sister chromatids becomes visible only during a sequence of mitosis known as metaphase (when chromosomes align together, attached to the mitotic spindle and prepare to divide). This DNA and its associated proteins and macromolecules is collectively known as chromatin, which is further packaged along with its associated molecules into a discrete structure called a nucleosome. Chromatin is present in most cells, with a few exceptions, for example, red blood cells. Occurring only in the nucleus of eukaryotic cells, chromatin composes the vast majority of all DNA, except for a small amount inherited maternally, which is found in mitochondria.

In prokaryotic cells, chromatin occurs free-floating in cytoplasm, as these cells lack organelles and a defined nucleus. Bacteria also lack histones. The main information-carrying macromolecule is a single piece of coiled double-helix DNA, containing many genes, regulatory elements and other noncoding DNA. The DNA-bound macromolecules are proteins, which serve to package the DNA and control its functions. Chromosomes vary widely between different organisms. Some species such as certain bacteria also contain plasmids or other extrachromosomal DNA. These are circular structures in the cytoplasm, which contain cellular DNA and play a role in horizontal gene transfer.

Compaction of the duplicated chromosomes during cell division ( mitosis or meiosis) results either in a four-arm structure (pictured above) if the centromere is located in the middle of the chromosome or a two-arm structure if the centromere is located near one of the ends. Chromosomal recombination during meiosis and subsequent sexual reproduction plays a significant role in genetic diversity. If these structures are manipulated incorrectly, through processes known as chromosomal instability and translocation, the cell may undergo mitotic catastrophe and die, or it may unexpectedly evade apoptosis leading to the progression of cancer.

In prokaryotes (see nucleoids) and viruses, the DNA is often densely packed and organized: in the case of archaea, by homologs to eukaryotic histones, and in the case of bacteria, by histone-like proteins. Small circular genomes called plasmids are often found in bacteria and also in mitochondria and chloroplasts, reflecting their bacterial origins.

Some authors, as in this article, use the term chromosome in a wider sense, to refer to the individualized portions of chromatin in cells, either visible or not under light microscopy. However, others use the concept in a narrower sense, to refer to the individualized portions of chromatin during cell division, visible under light microscopy due to high condensation.

Usage examples of "chromosome".

From the undoubted fact that gene mutations like the Tay-Sachs mutation or chromosomal abnormalities like the extra chromosome causing Down syndrome are the sources of pathological variation, human geneticists have assumed that heart disease, diabetes, breast cancer, and bipolar syndrome must also be genetic variants.

A single cistron is likely to be much less than 1 per cent of the length of a chromosome.

The Selfish Cistron nor The Selfish Chromosome, but The slightly selfish big bit of Chromosome and the even more selfish little bit of Chromosome.

Even a cistron is occasionally divisible and any two genes on the same chromosome are not wholly independent.

The largest practical unit of natural selection-the gene-will usually be found to lie somewhere on the scale between cistron and chromosome.

A dozen cistrons may be so close to each other on a chromosome that for our purposes they constitute a single long-lived genetic unit.

Neighbouring cistrons on the same chromosome form a tightly-knit troupe of travelling companions who seldom fail to get on board the same vessel when meiosis time comes around.

Humans had to be taught the kind of spatial sense the Crucians got gratis from their upbringing and from their chromosomes.

But your sperm contain only twenty-four chromosomes, with just half your deoxyribonucleic acid.

But if we sequenced your deoxyribonucleic acid, we could choose the better one of each pair of traits you yourself had inherited, and then we could manufacture a haploid set of chromosomes containing only those better traits.

With the codon writer, we will make a diploid set of chromosomes combining deoxyribonucleic acid from both of you.

It also seemed to be able to produce associated proteins, such as those used to bind deoxyribonucleic acid into chromosomes.

Nearly seventeen years previously, he had made this journey in the hope of discovering the secret of the Elder Eddas embroidered into the primitive Alaloi chromosomes.

When an animal is ready to reproduce, its germ-cellsor reproductive cellseach divide into two daughter cells called gametes, each daughter cell possessing one-half the chromosomes of the parent cell, every chromosome in each gamete corresponding to an opposite number chromosome in the other.

And the lyonization process, which inactivates one X chromosome in a female, almost always inactivates the structurally damaged one in cases like this, which means that, unlike males with the same problem, they survive.