why one DNA strand grows one nucleotide at a time and the other is assembled in short fragments?

Question

why one DNA strand grows one nucleotide at a time and the other is assembled in short fragments?

Answer 1

DNA is antiparallel, kinda like a 2 lane highway. One side runs one direction and the opposite complimentary side runs the other way.

Direction is assigned to a strand by referring to it as 5prime to 3prime (5' to 3') The 5' and 3' are in reference to the ribose part of the DNA. 5' refers to the number of the carbon to which the Phosphate (PO4) is attached. 3' refers to a hydroxyl group. (-OH) attached to the 3rd carbon of ribose. Thus ACGT becomes 5'ACGT3' (and the complimentary strand is also 5'ACGT3'.)

DNA is synthesized in a 5' to 3' direction. The enzyme that synthesizes the DNA (DNA polymerase) needs to see the complimentary strand and a 3' hydroxyl to proceed. The strand synthesized without interruption is the leading strand and the strand synthesized in pieces is the lagging strand.

In order to begin the synthesis of one of the lagging strand fragments, an RNA polymerase lays a short temporary piece of RNA down on the DNA strand so that the DNA polymerase can prime off of it. The priming RNA is removed.

The 64K question though is how is synthesis achieved all the way to very end of the lagging strand? The secret has to do with the teleomeres.

Answer 2

DNA replication is catalyzed by enzyme DNA polymerase.

DNA polymerase can only synthesize new DNA in a 5' to 3' direction, by complementary base pairing with template DNA.

During DNA replication, the ends of DNA is opend into a replication fork, one end has its 3' pointing out while the other have 5'

The DNA polymerase that reads the 3' end strand can synthesize the DNA smoothly after the primer in 5' to 3' direction. That is known as the leading strand that is synthesize.

For the other strand that have its 5' end sticking out, the DNA polymerase cannot synthesize new DNA strand in 3' to 5' direction smoothly like the leading strand. Therefore, there are primers attached along that strand where the DNA start to synthesize in 5' to 3' direction, the stop when it meets another primer. These form seperate fragments know as Okazaki fragments.

The Okazaki fragments are joined together by enzyme DNA ligase.

Answer 3

I'm think because one strand of DNA has a backbone the phosphate unit..............in other words one strand is the parental strand while the other is the new strand

The creation of the new strand is forced to move through the steps of A, T, C, and G, while the other is not..........

My Bio is a little rusty

Answer 4

Not sure if that will answer your question but dna arranges itself in codons which are three nucleotides and the are joined by those matching nucleotides on the other side

Answer 5

Wow! you will have located an excellent quantity of thought into this one question. likely weeks well worth of thought. . . . Then it rather is in lots of instances a similar stuff that disproves the FSM - only wonderin'