Chromosome - Chromosomal aberrations

The DNA which carries genetic information in biological cells is normally packaged in the form of one or more large macromolecules called chromosomes. A chromosome (in Greek chroma = color and soma = body) is, minimally, a very long, continuous piece of DNA, which contains many genes, regulatory elements and other intervening nucleotide sequences. In the chromosomes of eukaryotes, the uncondensed DNA exists in a quasi-ordered structure inside the nucleus, where it wraps around histones (structural proteins, Fig. 1 ...

Including:

• Chromosome - Chromosomes in plants yeast and animals
• Chromosome - Chromosomes in bacteria
• Chromosome - Chromatin
• Chromosome - Number of chromosomes in different species
• Chromosome - Karyotype
• Chromosome - Human
• Chromosome - Chromosomal aberrations

Read more here: » Chromosome: Encyclopedia - Chromosome

Some chromosome abnormalities do not cause disease in carriers, such as translocations, or chromosomal inversions, although they may lead to a higher chance of having a child with a chromosome disorder. Abnormal numbers of chromosomes or chromosome sets, aneuploidy, may be lethal or give rise to genetic disorders. Genetic counseling is offered for families that may carry a chromosome rearrangement. The gain or loss of chromosome material can lead to a variety of genetic disorders. Examples include: Cri du chat, which is c ...

See also:

Chromosome, Chromosome - Chromosomes in plants yeast and animals, Chromosome - Chromosomes in bacteria, Chromosome - Chromatin, Chromosome - Number of chromosomes in different species, Chromosome - Karyotype, Chromosome - Human, Chromosome - Chromosomal aberrations

Read more here: » Chromosome: Encyclopedia II - Chromosome - Chromosomal aberrations

Some chromosome abnormalities do not cause disease in carriers, such as translocations, or chromosomal inversions, although they may lead to a higher chance of having a child with a chromosome disorder. Abnormal numbers of chromosomes or chromosome sets, aneuploidy, may be lethal or give rise to genetic disorders. Genetic counseling is offered for families that may carry a chromosome rearrangement. The gain or loss of chromosome material can lead to a variety of genetic disorders. Examples include: Cri du chat, which is c ...

See also:

Chromosome, Chromosome - History, Chromosome - Chromosomes in plants yeast and animals, Chromosome - Chromosomes in bacteria, Chromosome - Chromatin, Chromosome - Number of chromosomes in different species, Chromosome - Karyotype, Chromosome - Human, Chromosome - Chromosomal aberrations

Read more here: » Chromosome: Encyclopedia II - Chromosome - Chromosomal aberrations

Two types of chromatin can be distinguished: Euchromatin, which consists of DNA that is active, e.g., expressed as protein. Heterochromatin, which consists of mostly inactive DNA. It seems to serve structural purposes during the chromosomal stages. Heterochromatin can be further distinguished into two types: Constitutive heterochromatin, which is never expressed. It is located around the centromere and usually contains repetitive sequences. Facultative heterochromatin, which is ...

See also:

Chromosome, Chromosome - History, Chromosome - Chromosomes in plants yeast and animals, Chromosome - Chromosomes in bacteria, Chromosome - Chromatin, Chromosome - Number of chromosomes in different species, Chromosome - Karyotype, Chromosome - Human, Chromosome - Chromosomal aberrations

Read more here: » Chromosome: Encyclopedia II - Chromosome - Chromatin

Normal members of a particular species all have the same number of chromosomes (see the table). Asexually reproducing species have one set of chromosomes, which is the same in all body cells. Gametes, reproductive cells, are haploid [n] and have one set of chromosomes. Sexually reproducing species have somatic cells, body cells, which are diploid [2n] having two sets of chromosomes, one from the mother and one from the father. Gametes are produced by meiosis of a diploid germ line cell. During meiosis, the matching chromosomes ...

See also:

Chromosome, Chromosome - History, Chromosome - Chromosomes in plants yeast and animals, Chromosome - Chromosomes in bacteria, Chromosome - Chromatin, Chromosome - Number of chromosomes in different species, Chromosome - Karyotype, Chromosome - Human, Chromosome - Chromosomal aberrations

Read more here: » Chromosome: Encyclopedia II - Chromosome - Number of chromosomes in different species

Normal members of a particular species all have the same number of chromosomes (see the table). Asexually reproducing species have one set of chromosomes, which is the same in all body cells. Gametes, reproductive cells, are haploid [n] and have one set of chromosomes. Sexually reproducing species have somatic cells, body cells, which are diploid [2n] having two sets of chromosomes, one from the mother and one from the father. Gametes are produced by meiosis of a diploid germ line cell. During meiosis, the matching chrom ...

See also:

Chromosome, Chromosome - Chromosomes in plants yeast and animals, Chromosome - Chromosomes in bacteria, Chromosome - Chromatin, Chromosome - Number of chromosomes in different species, Chromosome - Karyotype, Chromosome - Human, Chromosome - Chromosomal aberrations

Read more here: » Chromosome: Encyclopedia II - Chromosome - Number of chromosomes in different species

Bacterial chromosomes are often circular but sometimes linear. Some bacteria have one chromosome, while others have a few. Bacterial DNA also exists as plasmids. The distinction between plasmids and chromosomes is poorly defined, though size and necessity are generally taken into account. Bacterial chromosomes initiate replication and one origin of replication. When linear, bacterial chromosomes tend to be tethered to the plasma membrane of the bacteria. In molecular biology application, this allows for its isolation from plasmid DNA by centrifugation of lysed bacte ...

See also:

Chromosome, Chromosome - Chromosomes in plants yeast and animals, Chromosome - Chromosomes in bacteria, Chromosome - Chromatin, Chromosome - Number of chromosomes in different species, Chromosome - Karyotype, Chromosome - Human, Chromosome - Chromosomal aberrations

Read more here: » Chromosome: Encyclopedia II - Chromosome - Chromosomes in bacteria

Two types of chromatin can be distinguished: Euchromatin, which consists of DNA that is active, e.g., expressed as protein. Heterochromatin, which consists of mostly inactive DNA. It seems to serve structural purposes during the chromosomal stages. Heterochromatin can be further distinguished into two types: Constitutive heterochromatin, which is never expressed. It is located around the centromere and usually contains repetitive sequences. Facultative heterochromatin, which is ...

See also:

Chromosome, Chromosome - Chromosomes in plants yeast and animals, Chromosome - Chromosomes in bacteria, Chromosome - Chromatin, Chromosome - Number of chromosomes in different species, Chromosome - Karyotype, Chromosome - Human, Chromosome - Chromosomal aberrations

Read more here: » Chromosome: Encyclopedia II - Chromosome - Chromatin

Bacterial chromosomes are often circular but sometimes linear. Some bacteria have one chromosome, while others have a few. Bacterial DNA also exists as plasmids. The distinction between plasmids and chromosomes is poorly defined, though size and necessity are generally taken into account. Bacterial chromosomes initiate replication and one origin of replication. When linear, bacterial chromosomes tend to be tethered to the plasma membrane of the bacteria. In molecular biology application, this allows for its isolation from plasmid DNA by centrifugation of lysed bacte ...

See also:

Chromosome, Chromosome - History, Chromosome - Chromosomes in plants yeast and animals, Chromosome - Chromosomes in bacteria, Chromosome - Chromatin, Chromosome - Number of chromosomes in different species, Chromosome - Karyotype, Chromosome - Human, Chromosome - Chromosomal aberrations

Read more here: » Chromosome: Encyclopedia II - Chromosome - Chromosomes in bacteria