chromosomes & genes

Genetics as it applies to evolution, molecular biology, and medical aspects.

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chromosomes & genes

Post by angela » Wed May 18, 2005 1:42 am

how do genes and chromosomes work. i have a test on Friday and i don't know what to do. :(

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Inland Taipan
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Post by mith » Wed May 18, 2005 1:51 am

See dictionary on top right hand corner.
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Post by Poison » Wed May 18, 2005 5:11 pm

Or make a search in the forum.
Then we will be happy to make the things ,that you are confused about, more clear you. :)
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Post by b_d_41501 » Wed Jun 01, 2005 3:09 am

Genes are entities that parents pass to offspring during reproduction. These entities encode information essential for the construction and regulation of polypeptides, proteins and other molecules that determine the growth and functioning of the organism.

The word "gene" is shared by many disciplines, including classical genetics, molecular genetics, evolutionary biology and population genetics. Because each discipline models the biology of life differently, the usage of the word gene varies between disciplines. It may refer to either material or conceptual entities.

Following the discovery that DNA is the genetic material, and with the growth of biotechnology and the project to sequence the human genome, the common usage of the word "gene" has increasingly reflected its meaning in molecular biology. In the molecular-biological sense, genes are the segments of DNA which cells transcribe into RNA and translate, at least in part, into proteins.

In common speech, "gene" is often used to refer to the hereditary cause of a trait, disease or condition—as in "the gene for obesity." Speaking more precisely, a biologist might refer to an allele or a mutation that has been implicated in or is associated with obesity. This is because biologists know that many factors other than genes decide whether a person is obese or not: prenatal environment, upbringing, culture and the availability of food, for example.

Moreover, it is very unlikely that variations within a single gene—or single genetic locus—fully determine one's genetic predisposition for obesity. These aspects of inheritance—the interplay between genes and environment, the influence of many genes—appear to be the norm with regard to many and perhaps most ("complex" or "multifactoral") traits. The term phenotype refers to the characteristics that result from this interplay (see genotype-phenotype distinction).

A chromosome (in Greek chroma = colour 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), and where this composite material is called chromatin. During mitosis (cell division), the chromosomes are condensed and called metaphasic chromosomes. This is the only natural context in which individual chromosomes are visible with an optical microscope. Prokaryotes do not possess histones or nuclei. In its relaxed state, the DNA can be accessed for transcription, regulation, and replication. Chromosomes were first observed by Karl Wilhelm von Nägeli in 1842 and their behavior later described in detail by Walther Flemming in 1882. In 1910, Thomas Hunt Morgan proved that chromosomes are the carriers of genes.
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Post by MrMistery » Wed Jun 01, 2005 6:28 pm

genes are entities... Liked that one :D
Only read the first line of the post though :D
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