ohhhhh......ok so why couldnt the DNA molecule itself perform this function?

Answer 1

Previously we learned that DNA influences many of our characteristics. Now I will explain of how DNA does this.
DNA looks like a long double-stranded helix. The two strands are said to be complementary - the "sequence" on one strand determines sequence on the other. One reason for this is for protection against mutation. If something happens to one of the strands of DNA, it is possible to read the opposite strand to make a new copy of the damaged strand. To simplify things, think of DNA as a long piece of ticker-tape. Written on this ticker tape are all sorts of instructions, or genes. Genes are discrete units of information that tell cells what to do. For example, there might be a gene for brown hair or a gene for green eyes. Each one of our cells contains the exact same DNA sequences, or genes (with some exceptions). There are controls in place to make sure that the correct genes get expressed in the correct tissues - to ensure that you grow fingernails only on your fingers and hair only on specific parts on your skin, etc.

There are systems in our cells that read the DNA sequence and "translate" it into protein. Proteins are made by linking amino acids together. When you eat protein, it gets broken down into amino acids in your stomach - that's why it is important to eat enough protein! DNA contains the instructions, proteins carry out the instructions.

Common proteins
Name Function
Collagen Structural in skin
Keratin Waterproofing
Myosin Structural in muscle
Hemoglobin Carry oxygen in blood



So if DNA makes proteins and proteins perform functions, then the ultimate goal of genetic engineering is to alter proteins. Since proteins don't last very long, they are poor targets for genetic engineering. DNA is copied from one generation to the next, from parents to children. Changes in DNA can be carried over generations, making it a good target for lasting changes. There are two basic types of modifications - addition or deletion of function. To add a function to a cell all you have to do is introduce a new gene that codes for the given function. Deletion of function can be performed by either "knocking out" a gene or introducing an "antisense" gene to interfere with the cell's ability to express a given gene.

Next we will go over regulation of gene expression. Regulation is necessary to make sure that genes are only expressed in appropriate tissues.

Answer 2

Tons of reasons. Here are some... Having extra steps allows more types of regulation at different levels. It is also an amplification step. Let's assume that a certain type of molecules can generate a different type at a maximum rate of 10 molecules per minute. If you had DNA->protein then you would have maximum 10 protein molecules per min. When you have DNA->RNA->protein you can have 100 (1 DNA->10 RNA->10*10 protein) The mRNA can localize at different parts of the cell creating patterns within the cell. DNA can be safely stored in the nucleus (in eukaryotes) and parts that don't need to be transcribed can be safely packed together. Also in order to make DNA accessible to the ribosomes you would need to keep it unwound and single stranded for a very long time and that would take up too much energy (and space) RNA can be processed in different ways so that from the same sequence you can get more than one proteins The list goes on...

Answer 3

A DNA molecule simply depends upon RNA for transcription. It's like asking "Why does a woman need something from a male to have a baby?" It's just the way it is. It's all part of the process.

Answer 4

I assume you are referring to the difference between RNA and DNA. Simply put, DNA is like that book that you can't check out of the reference section of the library. It provides the basic information or blueprint and is reserved as a MASTER copy to keep the information safe from wear or damage. Or if you perfer, imagine you wrote a book. You'd keep one pristine copy at home--safe. You'd use another for your publisher to make changes to or to edit--a working copy. RNA is your working copy.

Answer 5

that's coz DNA can't unwind on it's own. This function is performed by an enzyme called reverse transcriptase. Dats why.
cya then
dee

Answer 6

What do you expect. Do you know how small a molecules brain is. They are nearly totally disabled.

Answer 7

What function.?? If your talking about what your brain has in it...well without IT functioning how do I answer what it is you are talking about??

Answer 8

Ummm... is there more to your question? To what function would you be referring?

Answer 9

Yea umm...more info please.