Conservapedia - User contributions [en]

Deoxyribonucleic acid

2007-09-23T04:43:12Z

Bigmike92: /* Modern understanding */

[[Image:799.gif|right|thumb|300px]]
'''Deoxyribonucleic acid''' (DNA) is an [[organic compound|organic]] [[chemical compound]] made up of [[molecule]]s shaped like a [[double helix]], a continuously twisted ladder.

DNA carries the [[gene|genet]]ic coding for the [[protein]]s that form the bodies of living [[organism]]s. All organisms contain DNA, and the DNA of a sexually reproducing organism is a mix of its parents' DNA.

==History==
In the late 19th century [[Friedrich Miescher]], a Swiss [[biochemist]], discovered several different proteins and an unusual [[acid]] in the [[nucleus]] of cells. The acid was named deoxyribonucleic acid, or DNA. In 1944 two American [[biologist]]s, [[Alfred Hershey]] and [[Martha Chase]] used experiments with [[bacteria]] and [[bacteriophages]] to show that DNA passed [[gene]]s from one generation to the next.

At that time, it was unclear how this simple molecule could hold all the complex information controlling the development of humans, animals and plants. Scientists knew it was made of four chemical bases called [[adenine]] (A), [[thymine]] (T), [[guanine]] (G) and [[cytosine]] (C), plus [[phosphoric acid]] and a [[sugar]]. They also knew that there was always the same amount of A as T and of G as C in cells, but they did not know the rules that controlled the arrangement.

British scientists [[Rosalind Franklin]] and [[Maurice Wilkins]] passed [[X-ray|X-rays]] through DNA to study the patterns made when the crystals diffracted them. From studying photographs of patterns, Rosalind Franklin concluded that DNA must be be a [[helix]]. [[James Watson]] and [[Francis Crick]], working in [[Cambridge]], used this information to help them solve the puzzle of DNA structure. They built a model showing that if A always paired with T and G paired with C, DNA must be like a ladder made of two strands twisted together in a double helix. The sugar and phosphoric acid were the sides of the ladder, and the rungs were the paired bases.

Watson and Crick suggested that DNA could unzip itself into two separate strands, and each strand could act as a pattern to grow a new strand. Crick showed later that each pair of genes worked in a group of three making the code for amino acids, the building blocks of proteins. These groups are called [[codon|codons]]. They make about fifty thousand different types of [[protein]], which make all the different types of cell in the body. Indian biochemist [[Har Gobind Khorana]] made all the possible codons and worked out which codons controlled which [[amino acid]].

If the DNA in one cell was stretched out, it would be about three feet long. Although DNA has a very simple structure, it can carry an enormous amount of information. Scientists do not yet understand all the DNA they see, but in 1991 a project called the [[Human Genome Project]] began to use computers to map the three billion base pairs which make up the 46 human [[chromosome|chromosomes]].

==Modern understanding==
[[Image:818.gif|right|thumb|Structure of DNA.]]
Small parts of DNA called [[gene]]s serve as the instructions for the body to carry out its functions and give rise to traits such as eye color, hair color, etc. <ref>"Eye-color genes, through the proteins they encode, direct the amount and placement of melanin in the iris." [http://www.hhmi.org/cgi-bin/askascientist/highlight.pl?kw=&file=answers%2Fgenetics%2Fans_044.html Ask A Scientist - Genes and eye color]</ref> Genes are packaged into [[chromosomes]]. Each individual human being has 23 pairs of chromosomes, where one set is inherited from his/her mother and the other set is inherited from his/her father.

[[Porkaryotic DNA]] is circular (a closed loop), while [[Eukaryotic DNA]] is linear (with ends) with the exception of [[Mitochondrial DNA]], which is circular too. DNA in [[porkaryote]]s usually consists only of one closed loop chromosome.<ref>Campbell, Neil A, et. al. ''Biology''. 6th ed. San Francisco: Benjamin Cummings, 2002. 299, 530-31.</ref>

DNA changes account for differences between individuals. However, they can also cause medical problems.

DNA is [[transcription|transcribed]] into [[RNA]], which is in turn being [[translation|translated]] into [[Amino Acids]] that that are used to form [[protein]]s which are the building blocks of all living creatures. [[RNA]] can also be reverse-transcribed back into DNA, which is the called [[Complimentary DNA]] or [[cDNA]].

==DNA fingerprinting==

DNA can help police track down criminals if an attacker leaves something like hair or blood at a crime scene. Everybody’s DNA is unique unless they are identical twins, and the genetic ‘fingerprint’ of this material can be enough to confirm if a suspect is guilty. Genetic fingerprinting can also show if somebody is closely related to somebody else. Archaeologists used samples from living relatives to identify whether bodies found buried in a forest in [[Russia]] were the remains of the [[Tsar]] and his family, killed during the 1919 [[Russian revolution]].

As well as showing how different we all are, DNA shows how much we are all the same. Only one small part of one chromosome distinguishes a boy from a girl. Genes give us different colored eyes, hair and skin, but 99.5% of any human's DNA is in the same order as everybody else’s, and 98.6% is the same as a chimpanzee’s.

Every living thing on earth has DNA that uses the same basic chemicals as human DNA, but because their chemicals are in a different order, the DNA of a worm or a tree encodes for different proteins, and those proteins make different cells. Evolutionists believe that all these cells developed from the first single-cell creatures formed three thousand million years ago, evolving gradually into new species to adapt to their environment. Creationists believe that God created all species the way they are now.

Whatever their individual beliefs, only human beings have learned to analyze and use their DNA, and only humans can learn to use that knowledge wisely.

==External links==
*[http://www.blackwellpublishing.com/trun/artwork/Animations/cloningexp/cloningexp.html Animated guide to DNA cloning]

== References ==
<references/>

[[Category:Genetics]]

James Watson

2007-09-23T04:42:24Z

Bigmike92:

James Dewey Watson is a well known [[atheist]] and an American geneticist who, with [[Francis Crick]], discovered the double helical structure of the [[DNA]] molecule. For this work he received the [[Nobel Prize]] for Medicine in 1962 together with Crick and Maurice Wilkins. His personal and informal account of this discovery "The Double Helix" aroused some controversy with it's frank account of the fiercely competitive nature of scientific research. In particular, he revealed that the crucial breakthrough was based on the work of [[Rosalind Franklin]], and her unpublished experimental results were used without her knowledge or permission. Franklin died before the Nobel Prize was awarded.

In 1968 he became director of the Cold Spring Harbor Laboratory in Long Island NY and in from 1988 helped direct [[The Human Genome Project]]

[[category:geneticists]]
[[category:Nobel Prize Winners]]

Diamond

2007-09-23T04:40:17Z

Bigmike92:

{{Mineral
| name=Diamond
| image=Rough_diamond.jpg
| cdesc=Carbon
| formula=C
| birefringence=None
| colors=Colorless. Impurities may produce pink, yellow, brown
| chabit=Octahedral
| csystem=Cubic
| cleavage=Perfect in four directions
| dispersion=0.044
| fracture=Conchoidal - step like
| hardness=10
| luster=Adamantine
| luminescence=
| nameorigin=Ancient Greek ''adamas'' - "invincible".
| optics=Singly refractive
| pleochroism=None
| sgravity=3.52
| spectral=In pale yellow stones a 415.5 nm line is typical. Irradiated and annealed diamonds often show a line around 594 nm when cooled to low temperatures.
| streak=Colorless
|}
}}
'''Diamond''' is an [[allotrope]] of [[carbon]], noted for being the hardest material on the [[hardness|Moh's Scale]], and also fairly rare (deposits are found in [[Kimberlite]] in [[South Africa]]). Diamonds are considered to be the strongest metal known to man. As such, natural diamonds are used for jewelry, and synthetic ones for drill bits.

==External Links==
[http://www.minelinks.com/alluvial/diamonds.html Minelinks.com - Diamonds]

Genome

2007-09-23T04:37:49Z

Bigmike92:

A genome is all the [[hereditary]] information held by an [[organism]], this includes both expressed and non-expressed [[genetic information]]. It is usually stored in [[DNA]] though the [[Retrovirus]] stores it in [[RNA]].

[[Eukaryotic cell|Eukaryote]]s (including humans) actually have two types of genomic material:
# chromosonal material: Information found inside the nucleus of a cell
# mitochondrial material: Information found inside a cytoplasm of a cell, specifically in the [[mitochondria]] (this separate genome is used as evidence for the [[Endosymbiotic hypothesis]]).<ref>http://www.medterms.com/script/main/art.asp?articlekey=3580</ref>

The [[Human Genome Project]] mapped the genome of humans (''Homo sapiens'') in a 11-year study, and is considered one of the marvels of modern human [[medicine]] and [[biology]]. All of the information is stored in a database.<ref>http://www.ornl.gov/sci/techresources/Human_Genome/home.shtml</ref> It is expected that the results of the project will allow scientists to predict how genetics influences drug interaction with the body, and lead to target specific drugs.<ref>[http://jama.ama-assn.org/cgi/content/abstract/285/5/540?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Implications+of+the+Human+Genome+Project+for+Medical+Science&searchid=1119480529280_6292&stored_search=&FIRSTINDEX=0&journalcode=jama]</ref>

Genomes of other species have been recorded as well, such as mice,<ref>http://www.ncbi.nlm.nih.gov/genome/guide/mouse/</ref> chimpanzees<ref>http://www.nature.com/nature/focus/chimpgenome/index.html</ref> and yeast.<ref>http://www.yeastgenome.org/</ref> The mouse genome sequence from the C57BL/6J strain has about 30,000 genes, and 99% of them have direct counterparts in humans.<ref>http://www.nature.com/nature/journal/v420/n6915/full/420509a.html</ref>

The chimpanzee represented the first non-human primate sequenced. The differences in the chimpanzee and human genomes are small, with 99% of the DNA sequence preserved. <ref>http://www.nih.gov/news/pr/aug2005/nhgri-31.htm</ref> The differences can be classified in terms of differences in local single nucleotide substitutions, insertions, deletions and repetitions of sequences. A relatively large number of difference between the chimpanzee and human genomes are not due to substitutions.<ref>http://207.210.67.162/~striz/docs/chimpc.pdf</ref> When this is taken into account, humans and chimpanzees still share 96% of their sequence, and are genetically closer than rats and mice.<ref>http://www.nih.gov/news/pr/aug2005/nhgri-31.htm</ref>

== Creationist View ==
Instead of seeing DNA as evidence for [[evolution]], creation scientists see DNA as confirming evidence of His divine plan. He has encoded into DNA His blueprints for making life. It is thus no surprise that the DNA of similar animals shares many sequences. DNA can be seen as a successful prediction of creation science.<ref>http://www.answersingenesis.org/docs2003/0425dna.asp</ref>
== References ==
<references/>

[[Category:Molecular Biology]]
[[Category:Medicine]]