Regarding Question 6-5: Can you please explain this more clearly?
Your answer refers to nonconservative; is this congruous
with semi-conservative or dispersive?
This is a different model.
Also, is it typical for the template to degrade after replication in conservative replication?
If the answer were semi-conservative or dispersive I would expect an intermediate line (assuming the DNA was not denatured - if it was denatured, then there would be two). Please explain part B also. How would it be unchanged? I could think that we would have more light strands.
This is a totally ridiculous, made up situtation to test your understanding. It is unheard of for the template to degrade or this type of replication to occur. In part B, and for every cycle of replication (in this artifical situation) you expect all new strands. If they are made of totally new nucleotides (newly made from materials in the medium), DNA will be all light. If the new strands are made of a mix of new (light) nucleotides and recycled old (heavy) nucleotides, then new DNA molecules will have intermediate density.
What do you mean by "non-conservative replication" in
prob 6-5. I seem to remember you only used the terms "conservative",
"semi-conservative" and "dispersive". It seems to me the only
possibility is conservative based on the picture (assuming you did not
denature the DNA and then lost the heavy strands). If you had
semi-conservative and didn't denature, you would have two light-heavy DNA
and the centrifugation after 1 generation would result in one
intermediate band. If dispersive replication occurred you would get one
intermediate band whether you denatured or not.
6-5 involves a new hypothetical possibility beyond the 3 considered in class. (It is pretty far fetched, and was invented only as a thought question. No one takes it seriously as a real possibility.) The situation in 6-5 is sort of like conservative if you then destroy the original template.
For problem 6-5, the answer indicates that non-conservative
replication could also result in a light band. What exactly
do you mean by non-conservative replication (i.e. are you
referring to dispersive or semi-conservative)? Wouldn't both
dispersive and semi-conservative replication result in an
intermediate band rather then a light band?
Nonconservative replication is a nonsensical invention for study purposes. It means the original template is destroyed after copies are made.