How does DNA polymerase grab the correct nucleotide for replication?

[fredreload]

So I got 2 questions here.

1. During replication, how does the DNA polymerase "read" the sequence and grab the correct counterpart? Is it because of the nature of the nucleotide, A attracts to T and C attracts to G? Or DNA polymerase actually has a way of grabbing the correct nucleotide?

2. There are free floating trophosphate nucleotides in the cell?

[NNY]

This YouTube video explains the beginning of the process in a simple manner.

https://youtu.be/cx582P7HkAc?t=229 

 

 

Edited June 16, 2018 by NNY