Nucleus of a cell

The double-helical DNA is packaged into a more compact structure by a number of proteins, most notably the basic proteins called histones. This condensation may serve a regulatory role and certainly has a practical purpose. The DNA present within the nucleus of a cell, if simply extended, would be about 1 meter long. The chromosomal proteins compact this long strand of DNA so that it can be packaged into a nucleus with a volume of a few cubic micrometers. 

Chromatin The material of chromosomes. It is a complex of DNA, histones, and nonhistone proteins (chromosomal proteins, non-histone) found within the nucleus of a cell. [NIH]... 

Cells of the eukaryotes contain true nuclei and are much larger and more complex internally than are those of prokaryotes. The nucleus of a cell contains most of its DNA and is separated from the cytoplasm by membranes. Within the cytoplasm are various organelles with characteristic structures. These include mitochondria, lysosomes, peroxisomes, and centrioles. Eukaryotic cells come in so many sizes and shapes and with so many specialized features that it is impossible to say what is typical. Nevertheless, Fig. 1-6 is an attempt to portray some sort of "average" cell, partly plant and partly animal. 

The amount of DNA in the nucleus of a cell (called the 2C or diploid amount of DNA) is specific to the type of organism in question. 

Double-Stranded Helix In most cases, DNA found in the nucleus of a cell is a helical double-stranded structure. Figure 12.63 represents the double-strand structure of a short section of DNA. The double strand is rather like a ladder. The sides of the ladder are formed by the phosphate sugar backbone. The rungs of the ladder are formed by the nitrogeneous bases. 

The strands of a DNA molecule are so fine that it is only possible to see them under a very powerful electron microscope. Using this instrument, a cell can be magnified 1,000 times. At this scale, the total length of the DNA in the nucleus of a cell is 3.1 kilometers (1.9 miles), about the distance between the Lincoln Memorial and the Capitol in Washington, DC. 

Nucleus The nucleus of an atom is the positively charged portion of the atom that contains protons and neutrons. Negatively charged electrons are found in the space around the nucleus. The nucleus of a cell, which is surrounded by a membrane, contains the chromosomes with their DNA and hereditary information. 

MICRONUCLEUS A nucleus, separate from and additional to the main nucleus of a cell, produced during telophase of mitosis or meiosis by lagging chromosomes or chromosomal fragments derived from spontaneous or experimentally induced chromosomal structural changes the smaller of the two nuclei that occur in the cells of ciliate protozoans. 

Chromosome Structure found in the nucleus of a cell these structures bear the DNA (deoxyribonucleic acid) from which genes are made. Genes carry the genetic code of the organism. 

Organelle A subcellular structure such as the mitochondrion or nucleus of a cell. 

In chemistry, the term nucleus (plural nuclei) is used for atoms as it is used for the nucleus of a cell in biology. 

Some chemicals can interact directly with the DNA or chromosomes in the nucleus of a cell. If this causes changes or major damage it can lead to a mutation. This means that the genetic code is altered so that cells that are derived from the ceU(s) with altered DNA are different. If this occurs in germ cells such as male sperm or female eggs and is passed on to a son or daughter, an inherited disease such as haemophilia can result. 

In the nucleus of a cell, DNA comprises a code carrying all the instructions that the cell needs to live. In the nuclei of eukaryotic cells, the DNA molecules, coiled like microscopic spaghetti, form compact, bulky structures called chromosomes. Under the light microscope, chromosomes have the appearance of solid, flexible rods. Early microscopists applied the word chromosome, meaning colored body, to structures that took up basic red or purple dyes in the nucleus of a dividing cell. Humans have 23 chromosomes, but other organisms, like the fruit fly, have as few as four, and others, such as the dog, as many as 39. 

Aneuploid The situation that exists when the nucleus of a cell does not contain an exact multiple of the haploid number of chromosomes one or more chromo-... 

DNA Deoxyribonucleic acid, a molecule located in the nucleus of a cell that carries the genetic information that is responsible for running that cell. 

The genome, defined as the total hereditary material (DNA) contained within the cells of an organism, is made up of individual molecules called nucleotides that contain the bases adenine (A), thymine (T), guanine (G) and cytosine (C). The DNA molecule is a double helix composed of two intertwined nucleotide chains oriented in opposite directions. These chains of nucleotides in DNA are wound up and compacted into the chromosomes that are found in the nucleus of a cell. 

B. Nucleus of a cell in a different organ from the cell making the prostanoid... 

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