A replication fork:

 

a) is only seen in prokaryotic chromosomes (NO)

b) is only seen in bacterial cells (NO)

c) is a Y shaped structure where both DNA strands are replicated simultaneously (should be NO as book calls it V shaped)

d) is a site where one DNA strand serves as a template but the other strand is not replicated

e) is created by the action of the enzyme RNA polymerase

 

 

Thanks so much for any help.

 

Looks pretty Y shaped to me. You'll also notice that both strands are copied (otherwise, you wouldn't end up with a net gain of DNA molecules.)

Looks that way to me too but book specifies v shape so that boggles me.

Looks that way to me too but book specifies v shape so that boggles me.

 

Books are not infallible you know. As a basic representation of an E.coli replication fork, the above diagram from e.coli is correct. It is for all intents and purpose "Y" shaped. There happens to be a "V" in there as well otherwise it couldn't be "Y" shaped could it?

 

[nitpick]The correct answer from the options is a little misleading, either that or I'm reading it wrong. It doesn't seem to account for the nature of the lagging strand. Am I just seeing a complication where there isn't one?[/nitpick]

are you annoyed by "simultaneously"?

 

I don't think its a real problem. The replication of leading and lagging strand starts at roughly the same time, even though the lagging strand takes longer, doesn't it?

Yea, of course books are not infallible. But if the teacher giving the test is using the book... Frankly, I just want to color in the right circle.

Yea, of course books are not infallible. But if the teacher giving the test is using the book... Frankly, I just want to color in the right circle.

fine, but if you're trying to argue that a Y shape and a V shape are too different, you're probably going to be too hung up on the details to do well on a test because you're going to miss the big picture. Try using deductive reasoning rather than memorizing the textbook word for word.

Nah, I am more trying to argue that my teacher is often a stickler for, "The book says..."

 

FWIW, I have the highest average in my class (95) and have gotten As on all tests thus far. This question is from a take home test. Monday afternoon we fill in the little circles for the scantron. I'll let you know what the official answer is.

 

 

BTW, I appreciate the challenge and debate.

Edited August 3, 200817 yr by bugaboo

i hate teachers like that... the ones that go 100% by the textbook are the ones that know the least about the material.

The answer is definately C... and seeing as your teacher is a trickster, you should know he wants to trick you into thinking Y is the wrong 1 whereas they are all the same. Just do the logical thing... do all options fail to answer the question? Which one answer comes close to been right? Clearly your answer there is C...

are you annoyed by "simultaneously"?

 

I don't think its a real problem. The replication of leading and lagging strand starts at roughly the same time, even though the lagging strand takes longer, doesn't it?

 

I think its more the stop-start nature of lagging strand replication that made me nit pick. I'm a bit of a stickler for using correct terminology and descriptives for that sort of thing, even where it blatantly doesn't make a difference. An odd foible of mine perhaps.

Actually I would not be disturbed by "simultaneously " either.

 

And Y or V is a pretty dumb distinction. If you monitor it you either see blobs (microscopy) a three-dimensional mess (crystallization, AFM). Hardly except for idealized drawings will you see anything precisely like a Y or V. I would possibly give extra points for mentioning that.

Answer was c. Thank you!

 

I got a 94 on the entire test so there you go, ecoli.