what would be the consequence if DNA were to contain uracil instead of thymine?

Answer 1

Cytidine can be changed to uracil by certain mutagens. If this happens in the DNA strand, the U would be based pair with an A, which is a mutation (it should be a C-G base pair). This would permantenly alter the DNA. By using thymine in DNA instead of uracil, the cell can recognize the mutation and fix it (ie it will remove any U's found in DNA and put in C's). This is not so important in RNA, as RNA is constantly being made and doesn't get passed down to the next generation like DNA. Uracil is a remnant of RNA-based life; when living organisms switched their genomes to DNA, they switched out the Uracil for Thymine.

Answer 2

I would have said it the other way round (RNA contains uracil instead of thymine), but whatever floats your boat :). Basically, thymine sticks to arganine better than uracil does. In double-stranded DNA, you want the strands to stick together pretty well most of the time. RNA contains uracil so it doesn't stay stuck to the DNA after transcription or get stuck to complementary RNA strands as easily.

Answer 3

I dont know the first strand so I cannot give the sequence but uracil can also be seen in RNA, uracil can never be located in DNA

we can only see Adenine, Guanine, Thymine, and Cytosine

Answer 4

Well, RNA polymerase does not recognize a template with uracil in it, so genes would not be transcribed. There are instances in DNA replication when a Uracil gets placed into DNA, but we have excision repair mechanisms to solve this problem.