DNA

DNA’nın hücredeki yeri

İnsan hücrelerinde bulunan DNA yaklaşık 3 milyar baz çiftinden oluşmuştur ve yaklaşık 1 metre uzunluğundadır. Bu 1 metre uzunluğundaki polimer, gözümüzle bile göremediğimiz küçüklükteki hücrenin çekirdeğinde saklanmaktadır. ‘Histon’ denilen proteinlere sarılarak paketlenip kromozomları oluşturan DNA bulunduğu küçücük yerde olduğu gibi durmamakta, gerekli olan gen bölgeleri enzimler vasıtası ile  açılıp kodların mRNA (messenger ribonükleik asit) denilen bir başka molekül vasıtası ile kopyaları çıkartılıp, bu kopya vasıtası ile proteinler sentezlenmektedir . Gerekli bölge bu şekilde okunduktan sonra DNA zinciri yine eski paketli haline dönmektedir. Ancak bir düşünün aynı anda bir değil belki onlarca farklı bölgeden DNA açılıp, gen şifreleri okunup yine kapatılmaktadır. Bir iplik yumağı düşünün ki, bu yumağın ortasından, başından sonundan bir yerleri aynı anda açılsın, sonra yine intizam bozulmadan sarılsın bu mümkün mü? İşte bu imkansız gibi görünen olay her an, her canlının her hücresinde hatasız, kusursuz, mükemmel bir şekilde üstelik cansız  atomlar, moleküller elleriyle yaptırılıyor.

The rDNA Policy Makers

When considering any issue it is important to determine which individuals will be involved. The ultimate decision is what authority that will grant the responsibility to the individual who will give the go-ahead to new and controversial scientific procedures. Relevant questions to ask are:
Should only the knowledgeable discuss and settle issues before the public is involved?
What input should a non-scientist have when it is unknown to what extent their lives will be affected by the new technology?
What input is necessary if a non-scientist does not understand the technical issues involved?
Conventional wisdom suggests scientists and administrators should decide. These individuals are considered to be the conventional decision makers. Hopefully the public may have an input into the initial decision making process. In the best case, the scientist and administrators know what is best for society as a whole. More and more, those at risk (from a process or a product) are demanding a say in the decision-making process.
The conventional decision makers will be confronted with several issues that will challenge their authority. What are these factors that challenge the conventional decision makers?
The virtue of having those at risk be involved in decision-making
Historical autonomy of scientists; but should this continue w/ public financial support of research?
Challenges to the legitimacy of current decision-making organizations are based on
University/industrial financial interdependency
Intense competition within science
Each could lead to decision made for the individual not public good.
Realization that science is not ethically neutral

Deoxyribonucleic acid, or DNA is a nucleic acid molecule that contains the genetic instructions used in the development and ********ing of all living organisms. The main role of DNA is the long-term storage of information and it is often compared to a set of blueprints, since DNA contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.

Chemically, DNA is a long polymer of simple units called nucleotides, which are held together by a backbone made of alternating sugars and phosphate groups. Attached to each sugar is one of four types of molecules called bases. It is the sequence of these four bases along the backbone that encodes information. This information is read using the genetic code, which specifies the sequence of the amino acids within proteins. The code is read by copying stretches of DNA into the related nucleic acid RNA, in a process called tran******ion. Most of these RNA molecules are used to synthesize proteins, but others are used directly in structures such as ribosomes and spliceosomes.

Within cells, DNA is organized into structures called chromosomes and the set of chromosomes within a cell make up a genome. These chromosomes are duplicated before cells divide, in a process called DNA replication. Eukaryotic organisms such as animals, plants, and fungi store their DNA inside the cell nucleus, while in prokaryotes such as bacteria it is found in the cell's cytoplasm. Within the chromosomes, chromatin proteins such as histones compact and organize DNA, which helps control its interactions with other proteins and thereby control which genes are transcribed.