Discussion in 'Science' started by ryobi, Mar 1, 2020.
What is the complementary DNA sequence to this strand of DNA???
5' CGA TTG 3'
Seriously? 3' GCT AAC 5'
See, that's what I thought but the test booklet is saying the correct answer is
5' CAA TCG 3'
I didn't think DNA was read in the 5' to 3' direction either only the 3' to 5' direction even on the daughter strand because DNA polymerase requires a free 3' OH group for the initiation of synthesis, ergo it can synthesize DNA in only one direction the 3' to 5' direction but the answer in the test booklet is intimating that the DNA on the daughter strand is formed in the 5' to 3' direction???
Ah, okay. They were looking for the build direction, not simply the paired sequence. Yeah, DNA pol has to add onto the 3' side, so reading the build sequence from left to right would be 5' CAA TCG 3'. I thought it sounded like a simple question. I guess that detail is what makes it GRE-level.
The polymerase binds to the OH group on the 3' prime end of the antisense strand but nucleotides are added in the 5' to 3' direction on the new strand therefore the new strand is read in the 5' to 3' direction???
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