Hey, I'd appreciate it if anybody could post me with some info on the following questions:

1. Function and Structure of Double Helix
2. What happens when DNA is altered?
3. Steps of DNA replication.

I'm not having you do my homework
I just need this for a major project, but it will be in my own words. Please don't use a lot of scientific terms, just something basic and easy to understand.

thanks
"Freedom"

1. The double helix is an "improved" version of the single helix (which is one structure of RNA). The double helix shape is improved because the genetic code contained therein is more resistant to mutations since, physically, the shape is more resistant to breaking and such and, chemically, the bases are better isolated. Also, think about this: If genetic code was contained in only one strand, any mutation would only need to occur to that strand alone, whereas for a double helix the mutation would need to occur on both strands to completely change the genetic code (this is because mutations always or almost always occur during DNA replication, when the structure is splitting). DNA is thought to be a mutation of RNA that survived natural selection because of its better stability.

2. DNA is altered by various methods. During replication, a chromosome (a continuous string of DNA) unwinds and separates via enzyme action (helicase, I think). After that, some stuff happens with enzymes where segments of DNA floating around in the nucleus join together into short strings and attach to the two single helix strands of DNA at different points along their length. I can't remember exact names or details, but I do know the enzyme DNA polymerase and something-primase are responsible for at least parts of the joining process. Since the joining occurs at various points, the different sections are joined together by an enzyme that, I think, is called DNA ligase. Anyway, the process of DNA replication is mediated by enzymes and although these enzymes are specialized to handle any mistakes, it's inevitable that during this process something out of all the sorts of things that can happen to differentiate the final structures from the original blueprint will happen. A piece of genetic code might be cut off during the unraveling and rejoining, pieces may cross over (e.g. strand AB and CD cross over some genes to become AD and CB), pieces might join where they shouldn't, more than one copy of the piece might join onto the code (example, if the DNA code is supposed to be A connected to C via B, and instead of just B something like B...B connects to the A and C, it might go unnoticed since the receptor site conditions are fulfilled in both cases).

3. I've described parts of the process already, but it's basically coiled chomosomes made of DNA uncoil and break the hydrogen bonds that connect the two helices together. The two single helices then attach to bases floating in the nucleus. Since a given nucleotide base only connects with one other base (these conjugate pairs are adenine-thymine and guanine-cytosine) because of the chemical structures of the bases, as well as Van der Waals forces, a method of automatic self-replication is possible - we can be sure that, barring mutation, the final DNA replicants are identical to the original since no other combination is possible. Think of differently shaped jigsaw pieces, if you like. Once the base pairs are made, the strands that connected to the original helices are joined to form a coherent helix themselves by enzymes. The new DNA then recoil, and we end up with two brand new, ideally identical, chromosomes.

I've given you the basic facts on DNA structure and function, but I suggest you read some text for more detail on how separate DNA strands attach (there is a certain order), the formal names for different types of mutations, the chemical relation between purines and pyrimidines, etc.

Wow
I just wanted to say thank you so much for taking the time to write all that. It is definetly very helpful!

"Freedom"

We can have very clear information on DNA replication in the below mentioned link
1) www.dnareplication.info/stepsofdnareplication.php