What is a "homogeneous" population?

[thebillsfan]

I saw this in some practice MCAT in a passage about population genetics, and was not exactly sure what it was referring to.

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[0Complications]

I saw this in some practice MCAT in a passage about population genetics, and was not exactly sure what it was referring to.

When you see a "Homo" does he/she like the same sex or a different sex? Are they the same or different?


Homo implies the same.

Homogeneous mixture is the same in the top as it is in the bottom. Any sample you take will be the same.


Homogeneous population is assumed to be the same.


You should focus on root words. They will help you out tremendously in the sciences. If you learn them you will be able to identify and define word combinations you have never seen before.

 

[thebillsfan]

0comp,

i realize homo means "same," but what i'm wondering is, in what sense are they the same? I doubt that it means that they all have the exact "same" genotypes, because that would be ridiculous. So, it must be "same" in some other respect...

 

[0Complications]

0comp,

i realize homo means "same," but what i'm wondering is, in what sense are they the same? I doubt that it means that they all have the exact "same" genotypes, because that would be ridiculous. So, it must be "same" in some other respect...

Sorry, I thought you were asking what a homogeneous population is.


Go with an outlandish example:


How about Giraffe's? Do they all have long necks or do some have short necks? Does the long neck give them a selective advantage?

I would say giraffe's are a homogeneous population of long necked animals. You can pick your traits. Sometime they are referring to genotype, but often they are referring to phenotype, because the phenotype is really what offers the selective advantage in an environment. The genotype just gets you to the phenotype, so you could have a heterozygous population, but only the individuals who have the dominant allele express the phenotype for X feature, and the homozygous recessive could die off if it is a fatal or unfit phenotype. It's just one of many examples.

My advice, if you're talking about populations, think phenotype unless you're given pertinent genetic information.

 

[capn jazz]

I think homogeneous population can also mean that if the population is 25% AA, 50% Aa, 25% aa, then any sampling of individuals can be assumed to be in the same genotypic proportions. Maybe I'm wrong though.

 

[0Complications]

I think homogeneous population can also mean that if the population is 25% AA, 50% Aa, 25% aa, then any sampling of individuals can be assumed to be in the same genotypic proportions. Maybe I'm wrong though.

This can't be a homogeneous population, because the aa is going to add variability. Assuming Mendelian genetics, you would have 3:1 ratio of A phenotype to aa phenotype. This would make the population heterogeneous.

At least that's my take.

 

[capn jazz]

Yea... I think you're right. A genetically homogeneous population would be homozygous for an allele.