what is the difference between plasmid DNA and

[Laura]

What is the difference between plasmid DNA and genomic DNA?

thanks

[srpkinja33]

the difference is in
1. size (plasmid DNA is smaller)
2. shape (plasmid DNA is circular, while genomic DNA is linear in eukaryotes, but also circular in bacteria)
3. organization (plasmid DNA is supercoiled, while eukaryotic genomic DNA is organized around histones)
4. origin (plasmid DNA belongs to plasmids, while genomic DNA belongs to some organism)

There is no difference in chemical composition - both are composed of nucleotides

[got_tent]

- the most important difference is that plasmid dna is extra-chromosomal -- it is not the main genome of the bacteria (you may think of plasmids "optional" or "extra" dna)

- some plasmids are present in high copy number (hundreds per cell), whereas there is only 1 copy of the main chromosome (okay, except just before division, there'll be two).

- plasmids are tiny compared to the main chromosome

- bacterial chromosomes can be circular or linear, as can be plasmids. often a bacteria with linear chromosomes has linear plasmids, but not necessarily (note that an older textbook which states that all plasmids are circular is outdated)

- plasmids are generally associated with prokaryotes, not eukaryotes. humans don't have naturally occurring plasmids.

- plasmids are commonly used as vectors in genetic engineering (e.g. pUC or pMCL for E. coli)

- plasmids can spread between related bacteria. it's worthy to note that antibiotic resistance is typically spread between species by plasmids

- a bacteria can have several different kinds of plasmids (just not two plasmids from the same incompatability group)

- the bacterial chromosome is anchored to the cell membrane to ensure each cell gets one copy following cell division, whereas plasmids are free-floating and distributed randomly between the two cells upon division

that's probably enough detail for a start; post another question if you have a specific question

[khri-khri]

Flamingo, common name for the four species of a family of birds having exceptionally long legs and long, highly flexible necks. Their relationship to other birds is uncertain; some evidence allies them with the herons and ibises, some with the ducks and geese; and there is fossil evidence suggesting a relationship to shorebirds. Their bills bend abruptly downward about midway; the upper mandible is narrow, and fits into the lower like the lid of a box. When they feed, flamingos dip the head under water and scoop backward with the head upside down. The edges of the bill have tiny narrow transverse plates called lamellae. The large fleshy tongue pressing against the inside of the bill strains the water out through the lamellae, leaving behind the small invertebrates and the vegetable matter upon which the bird feeds.

The largest species is the greater flamingo. It has two rather different subspecies, one vivid red and the other paler. The first of these breeds in the Caribbean area, from Yucatán and the West Indies to the coast of northeastern South America. It breeds well in captivity, and the occasional flamingo seen north of Florida probably escaped from a zoo. The paler flamingo inhabits Eurasia, in the Mediterranean area and Africa, east to India. Males of both subspecies may reach 155 cm (61 in) in height. The greater flamingo breeds in standing water or on low islands in shallow ponds, salt pans, and lagoons, building a conical mound of mud topped by a slight depression in which the one egg (rarely two) is laid. The young are fed on regurgitated food for as long as 75 days, although they can feed for themselves after about 30 days.

The Chilean flamingo is slightly smaller than the greater flamingo. It is pale pink, with bright red streaks on the back. It nests in high salt lakes in the Andes, and also in the lowlands of extreme southern South America. Two small species, the Andean flamingo and James's, or Puna, flamingo, also live in the Andes. The smallest and most abundant species, with a world population of at least 4 million, is the lesser flamingo of Africa east to India.

Scientific classification: Flamingos make up the family Phoenicopteridae of the order Ciconiiformes. They are sometimes placed in their own order, Phoenicopteriformes. The greater flamingo is classified as Phoenicopterus ruber, its vivid red subspecies as Phoenicopterus ruber ruber, and its paler subspecies as Phoenicopterus ruber roseus. The Chilean flamingo is classified as Phoenicopterus chilensis, the Andean flamingo as Phoenicopterus andinus, James's flamingo as Phoenicopterus jamesi, and the lesser flamingo as Phoenicopterus minor.
Gene, basic unit of heredity found in the cells of all living organisms, from bacteria to humans. Genes determine the physical characteristics that an organism inherits, such as the shape of a tree?s leaf, the markings on a cat?s fur, and the color of a human hair (see Heredity).

Genes are composed of segments of deoxyribonucleic acid (DNA), a molecule that forms the long, threadlike structures called chromosomes. The information encoded within the DNA structure of a gene directs the manufacture of proteins, molecular workhorses that carry out all life-supporting activities within a cell (see Genetics).

Chromosomes within a cell occur in matched pairs. Each chromosome contains many genes, and each gene is located at a particular site on the chromosome, known as the locus. Like chromosomes, genes typically occur in pairs. A gene found on one chromosome in a pair usually has the same locus as another gene in the other chromosome of the pair, and these two genes are called alleles. Alleles are alternate forms of the same gene. For example, a pea plant has one gene that determines height, but that gene appears in more than one form?the gene that produces a short plant is an allele of the gene that produces a tall plant. The behavior of alleles and how they influence inherited traits follow predictable patterns. Austrian monk Gregor Mendel first identified these patterns in the 1860s (see Mendel?s Laws).

In organisms that use sexual reproduction, offspring inherit one-half of their genes from each parent and then mix the two sets of genes together. This produces new combinations of genes, so that each individual is unique but still possesses the same genes as its parents. As a result, sexual reproduction ensures that the basic characteristics of a particular species remain largely the same for generations. However, mutations, or alterations in DNA, occur constantly. They create variations in the genes that are inherited. Some mutations may be neutral, or silent, and do not affect the function of a protein. Occasionally a mutation may benefit or harm an organism and over the course of evolutionary time, these mutations serve the crucial role of providing organisms with previously nonexistent proteins. In this way, mutations are a driving force behind genetic diversity and the rise of new or more competitive species that are better able to adapt to changes, such as climate variations, depletion of food sources, or the emergence of new types of disease (see Evolution).

Geneticists are scientists who study the function and behavior of genes. Since the 1970s geneticists have devised techniques, cumulatively known as genetic engineering, to alter or manipulate the DNA structure within genes. These techniques enable scientists to introduce one or more genes from one organism into a second organism. The second organism incorporates the new DNA into its own genetic material, thereby altering its own genetic characteristics by changing the types of proteins it can produce. In humans these techniques form the basis of gene therapy, a group of experimental procedures in which scientists try to substitute one or more healthy genes for defective ones in order to eliminate symptoms of disease.

Genetic engineering techniques have also enabled scientists to determine the chromosomal location and DNA structure of all the genes found within a variety of organisms. In April 2003 the Human Genome Project, a publicly funded consortium of academic scientists from around the world, identified the chromosomal locations and structure of the estimated 20,000 to 25,000 genes found within human cells. The genetic makeup of other organisms has also been identified, including that of the bacterium Escherichia coli, the yeast Saccharomyces cerevisiae, the roundworm Caenorhabditis elegans, and the fruit fly Drosophila melanogaster. Scientists hope to use this genetic information to develop life-saving drugs for a variety of diseases, to improve agricultural crop yields, and to learn more about plant and animal physiology and evolutionary history.