Questions!

[panicatthelunchbar]

Hi guys, I have a few questions if someone could please help out with!
These are from checkpoints, but i dont really like the answer that they provide :/

1. Which are most likely to be affected by crossing over - closely or distantly linked genes?
2. Can genes on different chromosomes become linked? Carefully explain.

I dont get the whole linked/unlinked stuff? I would appreciate if someone could explain in simple terms!

Thank you!

[stonecold]

Hi guys, I have a few questions if someone could please help out with!
These are from checkpoints, but i dont really like the answer that they provide :/

1. Which are most likely to be affected by crossing over - closely or distantly linked genes?
2. Can genes on different chromosomes become linked? Carefully explain.

I dont get the whole linked/unlinked stuff? I would appreciate if someone could explain in simple terms!

Thank you!

I haven't done this stuff in ages so I am not 100% sure...but

1.  Distantly linked genes are more likely to be affected by crossing over.  This is because the greater distance between the genes means it is more likely that the chiasmata will fall in this region and result in the genes undergoing recombination.
2.  Under normal circumstances I would think not.  The only way I could think this would happen in VCE at least would be if you have a translocation where a segment on one chromosome breaks off and attaches itself to a different chromosome.

Take a look at this video:
http://www.youtube.com/watch?v=2pcpZiKHbM8

I think it explains linked genes relatively well.

[Russ]

The answer to 2 is yes, because linkage is defined as "not segregating independently". Any circumstances that result in this happening means that they are linked

[stonecold]

^Listen to Russ because he has done/is doing?? genetics. 

[panicatthelunchbar]

Great! Thank you very much
The video is also very helpful, thanks!

[panicatthelunchbar]

Hi, this might be easy but

In an alien species, eye colours can be black, white or grey. A white-eyed mother and a black-eyed father have all grey children. What genetic pattern is most likely demonstrated here?

Is it co dominance or incomplete dominance? I dont really get the actual difference between the two :S

Could you please help!? Thanks

[stonecold]

Hi, this might be easy but

In an alien species, eye colours can be black, white or grey. A white-eyed mother and a black-eyed father have all grey children. What genetic pattern is most likely demonstrated here?

Is it co dominance or incomplete dominance? I dont really get the actual difference between the two :S

Could you please help!? Thanks

My teacher always told us that they were stupid terms and that they are the same.

The definitions however are that "co-dominance" is where both of the phenotypes are expressed (e.g. black and white splotches), whereas "incomplete dominance" is some kind of midpoint between the two extremes of the continuum.  So in this example, the midpoint of black and white is a grey colour.

But really, you are not actually getting grey pigment.  Rather, both the black and white pigments are actually produced, and then they mix or are equally distributed throughout the fur to appear "grey"

The only true example of incomplete dominance from a VCE standpoint is something like plant height.  i.e. if you cross a tall and a short plant you will probably get a medium sized plant.

[panicatthelunchbar]

That makes complete sense! Thanks stonecold