The Biological Question Thread

[stonecold]

lol.  sorry if sounds like i'm taking this out on everyone.  but this exam got me so frustrated.  and i am seriously counting on bio or else i'm screwed...

[cypriottiger]

likewise english and bio i need 42+

[stonecold]

likewise english and bio i need 42+

your lang analysis was good.  you should get the 42+ you want.  i'm screwed for english.  done absolutely nothing.  put all my eggs in the englang basket, and that isn't going too well either.

[cypriottiger]

likewise english and bio i need 42+

your lang analysis was good.  you should get the 42+ you want.  i'm screwed for english.  done absolutely nothing.  put all my eggs in the englang basket, and that isn't going too well either.

thanks but at least you have that increadable 48 from last year as a safety net. my 35 for business is gonna drop to 31, shouldve taken it more seriously for sacs...

[TrueLight]

And I still don't get the operon question from MC.  Why can't there be genes on a plasmid with an operon?

you can get genes organized in an operon  that are found on a plasmid

[stonecold]

likewise english and bio i need 42+

your lang analysis was good.  you should get the 42+ you want.  i'm screwed for english.  done absolutely nothing.  put all my eggs in the englang basket, and that isn't going too well either.

thanks but at least you have that increadable 48 from last year as a safety net. my 35 for business is gonna drop to 31, shouldve taken it more seriously for sacs...

thanks, but still there is a long way to go.  at least it will all be over soon.

We did this experiment in class it.  It was actually cool...

http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20101/bio%20101%20laboratory/bacterial%20transformation/results.htm

[cypriottiger]

http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20101/bio%20101%20laboratory/bacterial%20transformation/results.htm
coooooooollllll

[Milkshake]

Is there any difference between a probe and a marker?

[stonecold]

Is there any difference between a probe and a marker?

Yeah, a probe is a single stranded labelled piece of DNA which will hybridise with an allele if it is present, so it can be identified.

A marker is a gene which is located very closely to a gene of interest.  If the marker gene is inherited and expressed (i.e. it might produce a specific protein or something) then the gene of interest which is located close to the marker gene will also have been inherited, unless recombination has occurred between the two, which is less and less likely the closer together the two genes are.

[stonecold]

Okay, so I am a little confused about labelling of probes and DNA.  If you label your DNA, then obviously it will hybridise with the probe, and fluoresce.

However how do labelled probes work?  If you are looking for a single gene/ segment of DNA, you label your probe, then add it to your DNA sample.  How do you get rid of non hibridised probes without also washing away the DNA?

Or in each of the experiments, are one of them constantly fixed to a dish?

This is how I would think of DNA probing:
http://upload.wikimedia.org/wikipedia/en/a/a8/NA_hybrid.svg

How does it exist the other way around, where the probe is labelled and not the DNA?

[Russ]

They're probably fixed, I can't imagine it being too different to heatfixing for an enzyme assay but with a different technique.

I don't do these, but I'd guess that after adding a labelled probe the specific interaction with the target DNA will prevent it being washed away. This could be for a variety of reasons, depending on what lab technique you were using.

[jasoN-]

VCAA 2008 Q2a,  http://www.vcaa.vic.edu.au/vcaa/vce/studies/biology/pastexams/2008/2008biol2-w.pdf

Assessor's solution:
The newborn baby is DS 11, 15.
• either allele could have come from the mother
• neither allele could have come from the father

What's it saying? Is the child from the mother or not?
I wrote that it was not from the mother, as at least one of the 'DS' genes must have been inherited from the father (as we assume no mutations)
Don't know what the answer is saying

[Russ]

Didn't go through the paper, but those are just the two points they want you to make: either of the alleles could come from the mother (doesn't determine anything) but since neither could come from the father it's not his child.

[akira88]

VCAA 2008 Q2a,  http://www.vcaa.vic.edu.au/vcaa/vce/studies/biology/pastexams/2008/2008biol2-w.pdf

Assessor's solution:
The newborn baby is DS 11, 15.
• either allele could have come from the mother
• neither allele could have come from the father

What's it saying? Is the child from the mother or not?
I wrote that it was not from the mother, as at least one of the 'DS' genes must have been inherited from the father (as we assume no mutations)
Don't know what the answer is saying

What you've said is right
The baby has not inherited any of the father's alleles so it cannot be his child.

[stonecold]

VCAA 2008 Q2a,  http://www.vcaa.vic.edu.au/vcaa/vce/studies/biology/pastexams/2008/2008biol2-w.pdf

Assessor's solution:
The newborn baby is DS 11, 15.
• either allele could have come from the mother
• neither allele could have come from the father

What's it saying? Is the child from the mother or not?
I wrote that it was not from the mother, as at least one of the 'DS' genes must have been inherited from the father (as we assume no mutations)
Don't know what the answer is saying

What you've said is right
The baby has not inherited any of the father's alleles so it cannot be his child.

Yeah, it says it a bit further down that some people wrongly tried to argue it was his baby