kingpomba's question thread

[slothpomba]

Oh ok sweet, it was mentioned in a Insight exam and i was a bit taken aback, i thought liposomes and vectors and all that were more last semester.

I think (havent even looked it up) its DNA enclosed in like a lipid "case" wont waste time focusing on such silly things though

[slothpomba]

What is the difference between Co-Dominance, Incomplete Dominance & Partial Dominance?

Nature of biology only mentions co-dominance and in a little side note it says it is pretty much the same as incomplete and partial dominance but i'm fairly sure they're not.... i always thought nature of biology was a rather solid book as well..

I remember my teacher giving us examples of dominance:

* A flower has Red Alleles and White Alleles, The colour of the flower ends up as pink (mix of both evenly expressed throughout the flower)

*A horse has lets say... Red and Brown alleles, Some individual hair strands show the phenotype of Red only, some individual strands show the phenotype of brown only, so you get a horse with a mixture of red and brown hair, to make it easier lets just say the thing has red and brown patches, sort of like how some cows have black and white....


What kind of dominance do these two example represent (im pretty sure they're different kinds of dominance)

Thanks guys

[Russ]

I use the exact same examples haha. The flower is incomplete dominance. Imagine it as a spectrum, with one allele at each side. If you get a dominant allele then you get the extreme of the spectrum - codominance is when you see both of these in the phenotype (the horse). Incomplete is when neither can establish dominance so we get somewhere in between the two ends of the spectrum (the flower)

[pi]

incomplete dominance is no longer part of the current course as there is current debate as to whether or not is a type of co-dominance... just thought u guys should know...

[slothpomba]

I use the exact same examples haha

Good aren't they  

Ok and partial = incomplete also? just interchangeable terms?

Cheers thanks a lot

incomplete dominance is no longer part of the current course as there is current debate as to whether or not is a type of co-dominance... just thought u guys should know...

Oh shit... really? 
Damn... well that complicates things

[HERculina]

Co-dominance means that "the phenotype of an individual with two different alleles shows both traits"
example i always use for this is AB blood type

Partial/incomplete dominance is where "the heterozygote has a phenotype halfway between that of the homozygotes"
So the alleles are partially dominate and can be denoted as differently numbered capital letters e. A1, A2
i recall that pink carnations are partial dominant causer their phenotype is hallway between the phenotypes of the parents (pink = white + red carnations)

[stonecold]

Co-dominance means that "the phenotype of an individual with two different alleles shows both traits"
example i always use for this is AB blood type

Partial/incomplete dominance is where "the heterozygote has a phenotype halfway between that of the homozygotes"
So the alleles are partially dominate and can be denoted as differently numbered capital letters e. A1, A2
i recall that pink carnations are partial dominant causer their phenotype is hallway between the phenotypes of the parents (pink = white + red carnations)

The only time you really get incomplete dominance is generally for polygenic traits such as height, where you cross a tall plant and a short plant and get a medium plant for example.  This is a truly intermediate phenotype.

The flower scenario is technically wrong, because the flower doesn't produce pink pigment, it produces both red and white pigments, and these combine to form pink.  So it is really just another case of co-dominance.

[HERculina]

The only time you really get incomplete dominance is generally for polygenic traits such as height, where you cross a tall plant and a short plant and get a medium plant for example.  This is a truly intermediate phenotype.

The flower scenario is technically wrong, because the flower doesn't produce pink pigment, it produces both red and white pigments, and these combine to form pink.  So it is really just another case of co-dominance.

oh woopsies
...yea wat you sed

[slothpomba]

I emailed my teacher for her thoughts on the incomplete dominance, co dominance not being in the study design thing...

Anyway another question


[Source:TSSM 2009]

What do you guys make of this one?

Generally my definition is:

• Homologous - Same Structure Different Function
• Analogous - Different Structure Same Function

I'm not sure if these definitions are correct and i really lack any examples to keep in my head, so these would be appreciated...

My thought process for this one:

• IT was a bit confusing since it said the structure and function... were the same as the human eye.. that messes with my definitions...
• I knew we didnt share a recent common ancestor, so i eliminated  A & C
• Then i thought since structure was in the stem of the queston (2nd word there) they were trying to say both structures were the same and i kind of disregarded the function bit...
• Selected D

Answer turned out to be B....

Comments guys?

I think theres something wrong with my definitions

[stonecold]

I say dud question and think D is right.

[slothpomba]

Here is their answer:

[Source:TSSM 2009]


Anyone care to share their definitions/examples for homologous/analogous structures?  

[The Detective]

analogous --> wings of birds and butterflies (saw this in a practice exam)

[slothpomba]

Cheers mate

[slothpomba]

Thoughts on this one guys?

[Source:TSSM 2009]


D i dont need help with, i thought id just provide the sequence.

E, ill save you guys the trouble of finding an amino acid table, it changes the base sequence of a codon which codes for Arg to a stop codon.

I wrote that it was a nonsense mutation (A+ notes says when a codon is changed to become a stop codon it is called a nonsense mutation, which is what i wrote)






However the answers said this:






Got the other two marks though...

Should i stop referring to these things as nonsense mutations? or is it another bullshit question?

[Russ]

Nonsense mutation is just a general term for any early stop codon. I think they're being needlessly specific but I can see why they're requiring point mutation or base substitution.

Also, if the AA table wasn't given then you wouldn't be able to recognize it as a nonsense mutation.