Outcome of Ligation

[ho_yt]

Hi I'm new to this forum hope someone can answer my question. I want to ask is the following outcome possible in Ligation and why

 

1) 2 plasmids joined together

 

2) 1 DNA strain religate on its own

[CharonY]

Sounds like homework to me.

 

1) Do you mean whole plasmids?

 

2) This does not make sense. Do you mean DNA strand? Even so a single DNA strand does not ligate.

 

What precisely, do you think does ligation mean?

[ho_yt]

1) I mean 2 plasmids that had been cut by restriction enzyme, will both of them ligate together when a DNA ligase is added?

 

2) I mean when a DNA strain had been cut, will it religate like the plasmid?

[ecoli]

1) I mean 2 plasmids that had been cut by restriction enzyme, will both of them ligate together when a DNA ligase is added?

yes, if the restriction enzymes are compatible. You can only ligate two Watson-Crick base pairs together.

 

2) I mean when a DNA strain had been cut, will it religate like the plasmid?

if there are compitable sticky ends, otherwise you'll have to do blunt-end ligation.

[CharonY]

1) I mean 2 plasmids that had been cut by restriction enzyme, will both of them ligate together when a DNA ligase is added?

 

If you cut it with a single restriction enzyme, it depends on the recognition site of the enzyme and how often it appears in the respective plasmids. In the simplest case it is just a function of plasmid size. If there are more than one site in each plasmid, chances are high that the result is not a single fusion of two plasmids but rather (depending on fragments) a number of smaller, circular DNA fragments (which are usually instable in organisms). Also simple recirculization of the respective plasmids will occur with high frequency. Again, dependent on size this will usually occur with higher frequency than a plasmid fusion.

Normally type II restriction enzymes always generate compatible ends (either sticky or blunt) as the recognition site is palindromic.

 

I mean when a DNA strain had been cut, will it religate like the plasmid?

There is nothing like a DNA strain, only a DNA molecule. Do you mean a DNA strand instead? Single strand I mean? In that case, just envision how an enzyme cuts and think, how a single strand gets cut.