Biology Unit 4 Questions Megathread

[omgwtf123]

i am pretty sure u don't need to know all the complex detail about the lac operon, but knowing the basics would be a good idea

[Kaille]

help with a question...:S

Females horses have more DNA than male horses. Explain how this is possible if they both have 38 chromosomes in a somatic cell. (does it have something to do with X and Y chromosomes?)

[WhoTookMyUsername]

not sure of specific horse system, but X chromosome has more dna than Y chrommosome.
Female has 2xX chromosomes, male 1X +  1Y

e.g.

if X>Y
2xX > 1X and 1Y

[Kaille]

oh i see thanks

[HERculina]

during interphase do chromosomes exist?
what happens during prophase with the chromosomes?

[omgwtf123]

first question) chromosones do exist, but are thread-like , instead of condensed and short
second question) Nuclear envelope disappears, chromosones condense, centrioles allign at their respective poles, spindle fibres begin to form and attach onto chromosones and the nuceolus disappears.

[omgwtf123]

nucleolus****, but for ur question the most important thing is that chromosones are condensed and attach to spindle fibres

[omgwtf123]

Hope this helps

[HERculina]

yes it did
you know the supercoils in the chromosome though, do they form in interphase or prophase. cause when the chromosome condenses in prophase does this mean the supercoils form?

[omgwtf123]

1) Supercoils are formed in prophase and when the chromosone condenses, supercoils do in fact form. Hope this helps again

[Kaille]

are males not allowed/not able to have barr bodies? and in women, can the x chromosomes alternate from being deactivated (barr body) to activated?

[Russ]

Depends how you define "male". If you have an XY assortment then you're genetically male and you will never have a Barr body, because there's no second X chromosome to require deactivation. But you can be phenotypically male and be XXY (or XXXY etc.) and will thus have Barr bodies.

And no, they don't alternate between active/deactivated forms.

[WhoTookMyUsername]

Urgent SAC help please

second part of my sac tomorrow
just a couuple of questions


is an STR a hypervariable region? i've got some info saying yes and other saying no. also, whats the best definition of hypervariable region? a region that is... hyper... variable?


ALSO


does loading dye used in gel electrophoresis collectively refer to the loading dye, as well as glycerol and buffer solution?

if not,
is there a collective term?

[pi]

does loading dye used in gel electrophoresis collectively refer to the loading dye, as well as glycerol and buffer solution?

No, they are different.

Not sure on a general collective term, just go with 'loading dye and buffer solution'? Not sure

[Russ]

It's probably too late but STRs aren't really true hypervariable regions.