Chromosomes prokaryotic

Potentized homeopathic drugs are capable of producing effects on both prokaryotic and eukaryotic cells. Prokaryotic cells are usually smaller in size (1 - 10 pm) than eukaryotic ones (5 - 100 pm). Membrane-bound organelles like mitochondria, endoplasmic reticulum, Golgi complexes etc. are present in eukaryotic cells but absent in prokaryotic ones. While eukaryotic cells have nucleus containing DNA with histone and non-histone proteins in chromosoms, prokaryotic cells have no nucleus and their DNA with non-histone proteins lies in nucleoid without any membranous envelope. However, both types of cells are covered by plasma membrane with some common features. 

Bacteria Simple, single chromosome (prokaryote), usually single-celled organisms, 1-6 p,m diameter, spherical (coccus), or rod-like (bacillus) in shape Asexually, by binary fission (simple cell division) Air, water, and soil (sour milk, cheeses, yogurt, sauerkraut)... 

DNA in mammalian cells is organized in complex structures called chromosomes (prokaryotes do not have a nucleus, do not divide by mitosis, and do not, strictly speaking, have chromosomes). The DNA in the chromosomes of human and other eukaryotic cells is intimately associated with two classes of proteins called histones and nonhistones. Collectively, DNA, histones, and nonhistones constitute chromatin, from which the name chromosome is derived. The DNA in a chromosome is an extremely long, linear molecule that must be condensed and organized to fit into the chromosomes in the nucleus. (The DNA in the 46 human chromosomes would be about 1 m long if fully extended.) Histones are responsible for the structural organization of DNA in chromosomes the nonhistone proteins... 

Prokaryotic cells have only a single membrane, the plasma membrane or cell membrane. Because they have no other membranes, prokaryotic cells contain no nucleus or organelles. Nevertheless, they possess a distinct nuclear area where a single circular chromosome is localized, and some have an internal membranous structure called a mesosome that is derived from and continuous with the cell membrane. Reactions of cellular respiration are localized on these membranes. In photosynthetic prokaryotes such as the cyanobacteria,... 

Eukaryotic ceils possess a discrete, membrane-bounded nucleus, the repository of the cell s genetic material, which is distributed among a few or many chromosomes. During ceil division, equivalent copies of this genetic material must be passed to both daughter ceils through duplication and orderly partitioning of the chromosomes by the process known as mitosis. Like prokaryotic... 

Because of the double helical nature of DNA molecules, their size can be represented in terms of the numbers of nucleotide base pairs they contain. For example, the E. coli chromosome consists of 4.64 X 10 base pairs (abbreviated bp) or 4.64 X 10 kilobase pairs (kbp). DNA is a threadlike molecule. The diameter of the DNA double helix is only 2 nm, but the length of the DNA molecule forming the E. coli chromosome is over 1.6 X 10 nm (1.6 mm). Because the long dimension of an E. coli cell is only 2000 nm (0.002 mm), its chromosome must be highly folded. Because of their long, threadlike nature, DNA molecules are easily sheared into shorter fragments during isolation procedures, and it is difficult to obtain intact chromosomes even from the simple cells of prokaryotes. 

In terms of evolutionary biology, the complex mitotic process of higher animals and plants has evolved through a progression of steps from simple prokaryotic fission sequences. In prokaryotic cells, the two copies of replicated chromosomes become attached to specialized regions of the cell membrane and are separated by the slow intrusion of the membrane between them. In many primitive eukaryotes, the nuclear membrane participates in a similar process and remains intact the spindle microtubules are extranuclear but may indent the nuclear membrane to form parallel channels. In yeasts and diatoms, the nuclear membrane also remains intact, an intranuclear polar spindle forms and attaches at each pole to the nuclear envelope, and a single kinetochore microtubule moves each chromosome to a pole. In the cells of higher animals and plants, the mitotic spindle starts to form outside of the nucleus, the nuclear envelope breaks down, and the spindle microtubules are captured by chromosomes (Kubai, 1975 Heath, 1980 Alberts et al., 1989). 

Eukaryotic chromosomes, unlike their bacterial counterparts, are linear rather than- circular. Since RNA oligonucleotides prime both prokaryotic and eukaryotic DNA synthesis, the 5 termini of the daughter... 

Adolph KW. Chromosomes Eukaryotic, Prokaryotic and Viral, CRC Press, Boca Raton, FL, 1991. 

Following the first demonstration of the deleterious effect of radiation and ultimately that of chemicals on genetic material, numerous test systems have been used to study the induction of DNA damage, chromosomal aberrations, and mutations. This broad spectrum of activity resulted in the birth of genetic toxicology. The test organisms include prokaryotes (e.g., bacteria, fungi) and eukaryotes (e.g., yeast, fruit flies, plants, mammals). 

Yoshimura SH, Kim J, Takeyasu K (2003) On-substrate lysis treatment combined with scanning probe microscopy revealed chromosome structures in eukaryotes and prokaryotes. J Electron Microsc (Tokyo) 52 415-423... 

Plasmid A relatively (cf. the chromosome) small (>20 Kb), usually circular, double-stranded DNA molecule found in prokaryotes capable of replicating independently of the chromosome. Plasmids carry genes which are usually not essential for the growth of the organism except under special conditions. Some plasmids carry genes for antibiotic resistance. See also Ti-plasmid. Some plasmids however can be very large, e.g. the plasmids in Rhizobium species. 

Answer E. The 3 to 5 exonuclease activity of DNA pol 8 represents the proofreading activity of an enzyme required for the replication of human chromosomal DNA. DNA pol y (mitochondrial) and DNA pol III (prokaryotic) do not participate in this process, short RNA primers are replaced with DNA during replication, and new DNA strands are always... 

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