Question

I will fan and medal if someone can help me answer this. PLEASE?!

Answer 1

so the focus of this q is how we form double helix i guess?

Answer 2

That's what I was thinking, but I wasn't 100% sure.

Answer 3

im guessing its asking about formation of helix
now can you tell me what is nucleotide?

Answer 4

Not of the top of my head, but my textbook definition is:
Nucleotide: sub-unit of which nucleic acids are composed, made up of 5-Carbon sugar, a phosphate group, and a nitrogen base.

Answer 5

okay lets do this first
i have made a tutorial on structure of DNA and RNA
http://openstudy.com/study#/updates/54f7651ae4b091cfc28e2ae2
read it through first, just pay attention to DNA part
then we'll see if you can say how nucleotides and hydrogen bonds form the helix

Answer 6

pay attention to structures that are in pictures

Answer 7

To read it, it makes sense, but to explain it, I don't know. I am having a difficult time grasping this.

Answer 8

hm alright lets see

Nucleotides are the monomer of nucleic acid, that consists of a phosphate backbone, deoxyribose sugar and nitrogenous base.

A set of nucleotides bind together by phosphodiester bonds and form a single DNA strand.
The formation of DNA strand is always from 5' to 3' direction.

Two strand of DNA are connected to each other using Hydrogen bonds between the nucleotide's nitrogenous bases of each strand, namely 2 bonds between A and T, 3 bonds between C and G. As you can see, A always and always binds to T, C always binds to G.

Thats why the second strand of DNA that will form helix with our strand is said to be 'Complimentary' strand.

Now this complementary strand is ANTIPARALLEL to our strand, this makes it possible to have hydrogen bonds between the two strands and form this Double helix.