1. A Population Genetics Case Study: The Cheetah
When chasing down prey, cheetahs have a top sprinting speed of up to 60 miles (100 kilometers) per hour. It’s hard to imagine a better-adapted animal.
But even apart from human-caused problems related to hunting and the destruction of their habitat, cheetahs are in trouble. For one thing, cheetahs have extremely low fertility. Studies of cheetah sperm (collected by investigators who were trying to figure out why it was so hard to breed captive cheetahs in zoos and wildlife parks) have shown that
- Up to 79% of the sperm cells in any cheetah sperm sample are abnormal.
- Cheetah sperm count is low (only 25 million per ejaculate, much lower than in other species of cats).
The underlying problem is that cheetahs have extremely low genetic variability. It’s almost as if all cheetahs were members of the same family. They have much less genetic variation than other wild cats (source: The Cheetah in Genetic Peril, Scientific American, O’Brien, Wildt, and Bush). As we’ll see, this genetic uniformity could put the cheetah at risk of extinction. With very little variation, their ability to adapt to environmental change is limited.
To understand the cheetah’s genetic situation, we need to look at how genes are distributed and how genes change in populations. This field is known as population genetics. Let’s start.
2. Population Genetics Interactive Reading: Gene Pools, Fixed Alleles, Variable Alleles
[qwiz style=”width: 600px; border: 1px solid black;” qrecord_id=”sciencemusicvideosMeister1961-Gene Pool, Fixed and Variable Alleles (v2.0)”]
[h]The Gene Pool, Fixed Alleles, and Variable Alleles
[i]A gene pool
[q labels = “top”]
The first population genetics concept to understand is the gene pool. The gene pool is the total of all the ________ for all of the genes in a population.
To understand this concept, start by thinking of yourself. It took about 20,000 genes to spell out how to make your body, and to tell your body’s cells how to behave. You inherited these 20,000 genes from your ___________, receiving one copy from your mother, and a second from your father.
Now, you’re not the only person who has these ___________ genes. You ____________ your genes from your parents, so they have them. If you have siblings, they have these genes, too. So do your cousins. Every human being has the ______ set of genes.
[l]20,000
[fx] No. Please try again.
[f*] Excellent!
[l]alleles
[fx] No, that’s not correct. Please try again.
[f*] Good!
[l]inherited
[fx] No, that’s not correct. Please try again.
[f*] Good!
[l]parents
[fx] No, that’s not correct. Please try again.
[f*] Good!
[l]same
[fx] No, that’s not correct. Please try again.
[f*] Good!
[q labels = “top”]
Put together, all of these genes can be thought of as a cookbook. In this analogy, each of our 20,000 genes is a different _________: one recipe may be for a muscle protein. A second one may be for a digestive enzyme. To develop from a zygote, and for your body to properly function, you need to have two ________ of each of these 20,000 recipes. But those recipes aren’t ____________. In the same way as your recipe for tomato sauce might be slightly different from mine, it’s also possible that your mother’s genetic recipe for making a particular enzyme might be slightly different from your father’s. In genetics, these ______________ versions of a gene are known as alleles.
You can also think of this in terms of where genes are on chromosomes. A gene’s physical location on a chromosome is called its locus. At any locus, the DNA is going to code for the protein that this gene is responsible for. But the specific ___________ of DNA _________ might be different.
[l]alternative
[fx] No. Please try again.
[f*] Excellent!
[l]bases
[fx] No. Please try again.
[f*] Excellent!
[l]copies
[fx] No. Please try again.
[f*] Great!
[l]identical
[fx] No. Please try again.
[f*] Good!
[l]recipe
[fx] No. Please try again.
[f*] Great!
[l]sequence
[fx] No. Please try again.
[f*] Excellent!
[q labels = “top”]
Now, zoom out from thinking about your genes to thinking about the genes of an entire population. Every member of that ___________ will have the same genes. But there will be a variety of _______. On a very small scale, in a population with only five individuals and five genes, you can think about it like this.
| gene locus 1 | gene locus 2 | gene locus 3 | gene locus 4 | gene locus 5 | |
| Individual 1 | allele 1a only | allele 2a only | allele 3b only | allele 4a only | allele 5a only |
| Individual 2 | alleles 1a and 1b | allele 2a only | allele 3c only | allele 4a only | allele 5b only |
| Individual 3 | allele 1b only | allele 2a only | allele 3a only | allele 4a only | alleles 5a and 5b |
| Individual 4 | allele 1a only | allele 2a only | allele 3b and 3c | allele 4a only | alleles 5a and 5b |
| Individual 5 | alleles 1a and 1b | allele 2a only | allele 3b only | allele 4a only | allele 5b only |
Focus first on gene locus 1. If you follow the column downward, you can see that it has two alleles, allele 1a and allele 1b. By contrast, gene 2 has only one allele. Genes that have only one allele in an entire population are known as fixed alleles. Gene 3 has three alleles, the kind of situation that you’d find with the alleles for the ABO _______ type system, which also has three alleles (A, B, and o). Gene 4 is also a ________ allele.
Now, look at the individuals. Individual 1 happens to be ______________ for all five of the genes. But individual two is heterozygous for gene 1 and homozygous for the other genes.
[l]alleles
[fx] No. Please try again.
[f*] Good!
[l]blood
[fx] No, that’s not correct. Please try again.
[f*] Correct!
[l]fixed
[fx] No, that’s not correct. Please try again.
[f*] Great!
[l]homozygous
[fx] No, that’s not correct. Please try again.
[f*] Correct!
[l]population
[fx] No, that’s not correct. Please try again.
[f*] Correct!
[x]Great job. Now continue to the quiz below, which will help you master the concepts you just read about.
[restart]
[/qwiz]
3. Key Population Genetics Terms: Checking Understanding
The quiz below will test your mastery of everything we covered above.
[qwiz random = “true” style=”width: 600px; border: 3px solid black;” qrecord_id=”sciencemusicvideosMeister1961-Population Genetics Terms (v2.0)”][h]Population genetics key terms
[i]A gene pool
[q] The study of genes in populations is called
[c]IHBvcHVsYXRpb2 4gZ2VuZXRpY3M=[Qq]
[c]IHBvcHVsYXRpb24gc2NpZW5jZQ==[Qq]
[c]IG1vbGVjdWxhciBnZW5ldGljcw==[Qq]
[f]IENvcnJlY3QuIFRoZSBzdHVkeSBvZiBnZW5lcyBpbiBwb3B1bGF0aW9ucyBpcyBjYWxsZWQg4oCYcG9wdWxhdGlvbiBnZW5ldGljcy7igJk=[Qq]
[f]IE5vLiAmIzgyMjA7UG9wdWxhdGlvbiBzY2llbmNlJiM4MjIxOyBpcyB0b28gYnJvYWQuIENob29zZSBhbiBhbnN3ZXIgdGhhdCBpbmNsdWRlcyBib3RoIOKAmGdlbmV0aWNz4oCZIGFuZCDigJhwb3B1bGF0aW9u4oCZ[Qq]
[f]IE5vLiAmIzgyMjA7TW9sZWN1bGFyIGJpb2xvZ3kmIzgyMjE7IGZvY3VzZXMgb24gdGhlIG1vbGVjdWxlcyBvZiBoZXJlZGl0eSwgc3VjaCBhcyBETkEuIENob29zZSBhbiBhbnN3ZXIgdGhhdCBpbmNsdWRlcyBib3RoIOKAmGdlbmV0aWNz4oCZIGFuZCDigJhwb3B1bGF0aW9u4oCZ
Cg==[Qq]
[q] An alternative version of a gene is called a(n)
[c]IGdlbmUtYWx0[Qq]
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[c]IGdlbmUgdmFyaWFudC4=[Qq]
[f]IE5vLiBZb3UgbWFkZSBhIHNlbnNpYmxlIGNob2ljZSwgYnV0IHRoYXTigJlzIG5vdCB0aGUgdGVybSBpbiB1c2UuIFRoZSDigJhhbOKAmSB0aGF0IHN0YXJ0cyB0aGUgd29yZCDigJhhbHRlcm5hdGl2ZeKAmSBpcyBhIGNsdWUgdG8gdGhlIGFuc3dlci4=[Qq]
[f]IENvcnJlY3QuIOKAmEFsbGVsZeKAmSBpcyBhbiBhbHRlcm5hdGl2ZSB2ZXJzaW9uIG9mIGEgZ2VuZS4=[Qq]
[f]IE5vLiBZb3UgbWFkZSBhIHNlbnNpYmxlIGNob2ljZSwgYnV0IHRoYXTigJlzIG5vdCB0aGUgdGVybSBpbiB1c2UuIFRoZSDigJhhbOKAmSB0aGF0IHN0YXJ0cyB0aGUgd29yZCDigJhhbHRlcm5hdGl2ZeKAmSBpcyBhIGNsdWUgdG8gdGhlIGFuc3dlci4=
Cg==[Qq]
[q] Alleles can be thought of as different ‘recipes’ for the same
[c]IHRyYWl0[Qq]
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[f]IENvcnJlY3QuIEFsbGVsZXMgYXJlIHJlY2lwZXMgZm9yIGRpZmZlcmVudCB2ZXJzaW9ucyBvZiB0aGUgc2FtZSBnZW5lLiBHZW5lcyBjb2RlIGZvciBwcm90ZWlucy4gQW5kIHByb3RlaW5zIGFyZSB0aGUgbW9zdCBpbXBvcnRhbnQgZmFjdG9yIGJlaGluZCBhbiBvcmdhbmlzbeKAmXMgdHJhaXRzIChlaXRoZXIgZGlyZWN0bHksIG9yIGJ5IGNvbnRyb2xsaW5nIHRyYWl0cyB0aHJvdWdoIGVuenltZXMpLg==
Cg==[Qq]
[q] The total of all the alleles for all of the genes in a population is known as its
[c]IGdlbmV0aWMgZGl2ZXJzaXR5IGluZGV4Lg==[Qq]
[c]IGNvbWJpbmVkIGFsbGVsZSBlbnNlbWJsZS4=[Qq]
[c]IGdlbmUg cG9vbC4=[Qq]
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Cg==[Qq]
[q] The diagram below represents a gene pool for a population of five individuals with five genes. Is individual 4 homozygous or heterozygous for gene 3?
[c]IGhvbW96eWdvdXM=[Qq]
[c]IGhldGVyb3 p5Z291cw==[Qq]
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[f]IENvcnJlY3QuIEluZGl2aWR1YWwgNCBoYXMgdHdvIGRpZmZlcmVudCBhbGxlbGVzIGZvciBnZW5lIDMgKGFsbGVsZXMgM2IgYW5kIDNjKSwgbWFraW5nIGhpbSBvciBoZXIgaGV0ZXJvenlnb3VzIGZvciB0aGF0IGdlbmUu
Cg==[Qq]
[q] The diagram below represents a gene pool for a population of five individuals with five genes. If we use the symbol ‘A’ to represent gene 1, which of the following makes sense as a representation of individual 2’s genotype for that gene?
[c]IEFB[Qq]
[c]IE Fh[Qq]
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[f]IE5vLiBJbmRpdmlkdWFsIDIgaXMgYSBoZXRlcm96eWdvdGUgZm9yIGdlbmUgMSAoaGUgb3Igc2hlIGhhcyB0d28gZGlmZmVyZW50IGFsbGVsZXMpLiDigJhhYeKAmSB3b3VsZCBiZSB0aGUgZ2Vub3R5cGUgb2YgYW4gaW5kaXZpZHVhbCB3aG8gd2FzIGhvbW96eWdvdXMgcmVjZXNzaXZlLiBUaGluayBvZiBhIHJlcHJlc2VudGF0aW9uIHRoYXQgd291bGQgc2hvdyB0aG9zZSB0d28gYWxsZWxlcyBhcyBiZWluZyBkaWZmZXJlbnQu
Cg==[Qq]
[q] The diagram below represents a gene pool for a population of five individuals with five genes. Is gene 5 a fixed allele?
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[c]IE5vLiBHZW5lIDUgaXMgTk9U IGEgZml4ZWQgYWxsZWxlLg==[Qq]
[f]IEluY29ycmVjdC4g4oCYRml4ZWTigJkgYWxsZWxlIG1lYW5zIHRoYXQgdGhlcmXigJlzIG9ubHkgb25lIGFsbGVsZSBpbiB0aGUgZW50aXJlIHBvcHVsYXRpb24gZm9yIHRoYXQgZ2VuZS4gSWYgeW91IGxvb2sgYXQgdGhlIOKAmGdlbmUgNeKAmSBjb2x1bW4sIHlvdSBjYW4gc2VlIHRoYXQgdGhlcmUgYXJlIFRXTyBhbGxlbGVzIChhbGxlbGVzIDVhIGFuZCA1Yiku[Qq]
[f]IENvcnJlY3QuIElmIHlvdSBsb29rIGF0IHRoZSDigJhnZW5lIDXigJkgY29sdW1uLCB5b3UgY2FuIHNlZSB0aGF0IHRoZXJlIGFyZSBUV08gYWxsZWxlcyAoYWxsZWxlcyA1YSBhbmQgNWIpLiBUaGVyZWZvcmUsIHRoZSBhbGxlbGUgaXMgbm90IGZpeGVkLg==
Cg==[Qq]
[q] The diagram below represents a gene pool for a population of five individuals with five genes. Is gene 2 a fixed allele?
[c]IFllcy4gR2VuZSAyIGlzIG EgZml4ZWQgYWxsZWxlLg==[Qq]
[c]IE5vLiBHZW5lIDIgaXMgTk9UIGEgZml4ZWQgYWxsZWxlLg==[Qq]
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Cg==[Qq]
[q]A problem threatening cheetah survival is
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[c]wqBoaWdoIHNwZXJtIGNvdW50cw==[Qq]
[c]wqB0b28gbXVjaCB2YXJpYWJpbGl0eSBiZXR3ZWVuIG1lbWJlcnMgb2YgdGhlIHBvcHVsYXRpb24u[Qq]
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[f]IE5vLsKgQ2hlZXRhaHMgYXJlIGZhY2luZyB0aGUgb3Bwb3NpdGUgcHJvYmxlbTogdGhlcmUgaXMgYWJub3JtYWxseSA=bG93IHZhcmlhYmlsaXR5IGFtb25nIGNoZWV0YWhzLg==
Cg==[Qq]
[q]Compared to other cat species, genetic variation among cheetahs is
[c]IGhpZ2hlcg==[Qq]
[c]wqBhYm91dCB0aGUgc2FtZQ==[Qq]
[c]IGxv d2Vy[Qq]
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Cg==[Qq]
[q] Compared to other species of wild cats, you would expect cheetahs to have
[c]wqBmZXdlciBmaXhlZCBhbGxlbGVz[Qq]
[c]wqBtb3JlIGZpeG VkIGFsbGVsZXM=[Qq]
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[x]
[restart]
[/qwiz]
4. Allele Frequency
Allele frequency is another key concept in population genetics. Allele frequency is how common an allele is in a gene pool. It’s usually stated as a decimal or a percentage.
4.a. Counting Alleles
Here’s an example. The table below represents the alleles for one gene in a population of 20 mice. In this population, we’re going to look at two phenotypes: albino (white, with no pigmentation), and normal (pigmented). Two alleles control this phenotype: “A” codes for normal color, and “a” codes for albino coloration.
|
|
|
| aa | Aa | AA | AA | aa |
| AA | aa | Aa | Aa | AA |
| AA | aa | AA | AA | aa |
| Aa | Aa | aa | Aa | aa |
To find the frequency of the “a” allele, start by counting each “a” allele within this gene pool. If an individual’s genotype is “aa” then count two “a” alleles. If the individual is “Aa,” then count one “a” allele. In other words, in the first row, you’d count a total of five “a” alleles.
Go ahead and count up all the “a” alleles in each row of the gene pool. Drag the correct number into the column on the right. Then drag the total into the lower right.
[qwiz style = “border: 2px solid black;” qrecord_id=”sciencemusicvideosMeister1961-Counting Alleles (v2.0)”]
[h]Counting alleles
[q labels = “top”]
| aa | Aa | AA | AA | aa | ___ |
| AA | aa | Aa | Aa | AA | ___ |
| AA | aa | AA | AA | aa | ___ |
| Aa | Aa | aa | Aa | aa | ___ |
| Total of “a” alleles in this population | ___ | ||||
[l]1
[fx] No, that’s not correct. Please try again.
[f*] Correct!
[l]2
[fx] No. Please try again.
[f*] Excellent!
[l]3
[fx] No, that’s not correct. Please try again.
[f*] Great!
[l]4
[fx] No, that’s not correct. Please try again.
[f*] Good!
[l]5
[fx] No, that’s not correct. Please try again.
[f*] Excellent!
[l]6
[fx] No, that’s not correct. Please try again.
[f*] Great!
[l]7
[fx] No. Please try again.
[f*] Excellent!
[l]8
[fx] No. Please try again.
[f*] Great!
[l]9
[fx] No, that’s not correct. Please try again.
[f*] Good!
[l]10
[fx] No. Please try again.
[f*] Good!
[l]11
[fx] No. Please try again.
[f*] Good!
[l]12
[fx] No. Please try again.
[f*] Correct!
[l]15
[fx] No, that’s not correct. Please try again.
[f*] Good!
[l]20
[fx] No, that’s not correct. Please try again.
[f*] Great!
[/qwiz]
4.b. Figuring out allele frequencies
To figure out the frequency of “a”, take the number of “a” alleles, and divide by the total number of alleles for this gene. Since there are 20 individuals, there are a total of 40 alleles. 20/40 = ½ or 0.5 or 50%.
Here are a few questions to check to see if you’re getting this.
[qwiz random = “true”;style = “border: 3px solid black;” qrecord_id=”sciencemusicvideosMeister1961-Allele Frequency (v2.0)”]
[h]Allele frequency
[i]
|
|
[q]In this gene pool, the frequency of “a”, expressed as a fraction, is
| aa | aa | AA | Aa | aa |
| AA | aa | aa | Aa | aa |
[c]MTAvMjA=[Qq]
[c]MTQv MjA=[Qq]
[c]Ni8yMA==[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuIEZyb20geW91ciBhbnN3ZXIsIEkmIzgyMTc7bSBndWVzc2luZyB0aGF0IHlvdSBqdXN0IGNvdW50ZWQgaW5kaXZpZHVhbHMgd2hvIGFyZSAmIzgyMjA7YWEuJiM4MjIxOyBZb3UgaGF2ZSB0byBjb3VudCB0aGUgYWxsZWxlcyBpbiB0aGUgaGV0ZXJvenlnb3RlcywgdG9vLg==[Qq]
[f]TmljZSBqb2IuIFRoZXJlIGFyZSAxNCAmIzgyMjA7YSYjODIyMTsgYWxsZWxlcywgc28gdGhlIGZyZXF1ZW5jeSBvZiAmIzgyMjA7YSYjODIyMTsgaXMgMTQvMjAuIE9mIGNvdXJzZSwgdGhhdCYjODIxNztzIGJlc3QgcmVkdWNlZCB0byA3LzEwLCBidXQgdGhhdCB3YXNuJiM4MjE3O3QgYW4gb3B0aW9uJiM4MjMwOw==[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuIEZyb20geW91ciBhbnN3ZXIsIEkmIzgyMTc7bSBndWVzc2luZyB0aGF0IHlvdSBjb3VudGVkIHRoZSAmIzgyMjA7QSYjODIyMTsgYWxsZWxlIGluc3RlYWQu
Cg==[Qq]
[q]In this gene pool, the frequency of “a”, expressed as a percentage is
| aa | aa | AA | Aa | aa |
| AA | aa | aa | Aa | aa |
[c]MzAl[Qq]
[c]NTAl[Qq]
[c]Nz Al[Qq]
[c]ODAl[Qq]
[c]OTAl[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuwqBDb252ZXJ0IHRvIGEgJS4gTWFrZSBzdXJlIHlvdSBjb3VudCB0aGUgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZXMgaW4gdGhlIGhldGVyb3p5Z290ZXMu[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuwqBDb252ZXJ0IHRvIGEgJS4gTWFrZSBzdXJlIHlvdSBjb3VudCB0aGUgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZXMgaW4gdGhlIGhldGVyb3p5Z290ZXMu[Qq]
[f]RXhjZWxsZW50LiBUaGVyZSBhcmUgMTQgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZXMsIG91dCBvZiBhIHRvdGFsIG9mIDIwIGFsbGVsZXMuIDE0LzIwID0gNzAl[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuwqBDb252ZXJ0IHRvIGEgJS4gTWFrZSBzdXJlIHlvdSBjb3VudCB0aGUgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZXMgaW4gdGhlIGhldGVyb3p5Z290ZXMu[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuwqBDb252ZXJ0IHRvIGEgJS4gTWFrZSBzdXJlIHlvdSBjb3VudCB0aGUgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZXMgaW4gdGhlIGhldGVyb3p5Z290ZXMu
Cg==[Qq]
[q]In this gene pool, the frequency of “A”, expressed as a percentage is
| aa | aa | AA | Aa | aa |
| AA | aa | aa | Aa | aa |
[c]Mz Al[Qq]
[c]NTAl[Qq]
[c]NzAl[Qq]
[c]ODAl[Qq]
[c]OTAl[Qq]
[f]RXhjZWxsZW50LiBUaGVyZSBhcmUgNsKgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMsIG91dCBvZiBhIHRvdGFsIG9mIDIwIGFsbGVsZXMuIDYvMjAgPSAzMCU=[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuwqBDb252ZXJ0IHRvIGEgJS4gTWFrZSBzdXJlIHlvdSBjb3VudCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMgaW4gdGhlIGhldGVyb3p5Z290ZXMu[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuwqBDb252ZXJ0IHRvIGEgJS4gTWFrZSBzdXJlIHlvdSBjb3VudCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMgaW4gdGhlIGhldGVyb3p5Z290ZXMu[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuwqBDb252ZXJ0IHRvIGEgJS4gTWFrZSBzdXJlIHlvdSBjb3VudCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMgaW4gdGhlIGhldGVyb3p5Z290ZXMu[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuwqBDb252ZXJ0IHRvIGEgJS4gTWFrZSBzdXJlIHlvdSBjb3VudCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMgaW4gdGhlIGhldGVyb3p5Z290ZXMu
Cg==[Qq]
[q]In this gene pool, the frequency of “A”, expressed as a decimal is
| aa | aa | AA | Aa | aa |
| AA | aa | aa | Aa | aa |
[c]MC4y[Qq]
[c]MC 4z[Qq]
[c]MC41[Qq]
[c]MC43[Qq]
[c]MC45[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuwqBDb252ZXJ0IHRvIGEgZGVjaW1hbC4gTWFrZSBzdXJlIHlvdSBjb3VudCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMgaW4gdGhlIGhldGVyb3p5Z290ZXMu[Qq]
[f]WWVzLiBUaGVyZSBhcmUgNiAmIzgyMjA7QSYjODIyMTsgYWxsZWxlcywgb3V0IG9mIGEgdG90YWwgb2YgMjAgYWxsZWxlcy4gNi8yMCA9IDAuMw==[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuwqBDb252ZXJ0IHRvIGEgZGVjaW1hbC4gTWFrZSBzdXJlIHlvdSBjb3VudCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMgaW4gdGhlIGhldGVyb3p5Z290ZXMu[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuwqBDb252ZXJ0IHRvIGEgZGVjaW1hbC4gTWFrZSBzdXJlIHlvdSBjb3VudCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMgaW4gdGhlIGhldGVyb3p5Z290ZXMu[Qq]
[f]Tm8uIFlvdSBoYXZlIHRvIGNvdW50IGFsbCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMsIGFuZCB0aGVuIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMuwqBDb252ZXJ0IHRvIGEgZGVjaW1hbC4gTWFrZSBzdXJlIHlvdSBjb3VudCB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZXMgaW4gdGhlIGhldGVyb3p5Z290ZXMu[Qq]
[/qwiz]
5. Misconception Alert! “Dominant Allele” does not mean “Most Common Allele”
The case of the Peppered moth allows us to demolish a misconception about genes and populations: the false idea that dominant alleles, because they’re dominant, must be common. Intuitively, it makes sense: if these alleles are dominant, why don’t they come to dominate? However, this intuition is wrong. What we’ll see is that the frequency of an allele has nothing to do with whether it is dominant or recessive.
Read below, dragging in the correct term as needed
[qwiz style=”width: 600px; border: 1px solid black;” qrecord_id=”sciencemusicvideosMeister1961-Misconception Alert, Dominant Alleles (v2.0)”]
[h]Misconception Alert: Dominant Alleles
[i]
[q labels = “top”]
Let’s start by looking at some data about diseases caused by dominant alleles. One such disease is Achondroplasia: it’s a form of dwarfism. If you inherit the gene for this condition, you’ll be born with extremely _______ limbs. The condition is rare: According to the US national library of medicine, (http://ghr.nlm.nih.gov/condition/achondroplasia) the condition occurs in between 1/15,000 and 1/40,000 newborns. So, it’s caused by a dominant allele, and it’s _____.
The same is true of Huntington’s disease, a disease of the nervous system, also caused by a dominant allele. Huntington’s is extremely ______: it shows up in 3 to 7 of every 100,000 births in people of European ancestry. It’s even less common in some other populations, including people of Japanese, Chinese, and African descent.
[l]short
[fx] No. Please try again.
[f*] Great!
[l]rare
[fx] No. Please try again.
[f*] Great!
[q labels= “top”]
Similarly, think of other phenotypes which in a genetic sense, are recessive. If you went up to Norway or Sweden, you’d see a lot of people with blond ______ and blue eyes. While both of these phenotypes are caused by multiple genes, the dominant alleles for darker hair and brown eyes are both somewhat rare in these populations, while the ___________ alleles (for blond hair and blue eyes) are much more common.
The confusion might come from the word “dominant.” When we think of something that’s dominant, we think that it should be able to overcome something less dominant. But while that works in the genotype and phenotype of a single person, with dominant alleles __________ recessive alleles, it doesn’t work in a population’s gene pool.
We can extend this idea a little further. Dominant alleles, as we’ve seen, won’t increase in ____________. And unless certain processes are at work in a gene pool, any allele’s frequency will stay about the same. If allele frequencies are changing, then some evolutionary process is at work in that population. In an upcoming tutorial in this series, we’ll start looking at what those processes are.
[l]frequency
[fx] No. Please try again.
[f*] Correct!
[l]hair
[fx] No. Please try again.
[f*] Good!
[l]masking
[fx] No, that’s not correct. Please try again.
[f*] Correct!
[l]recessive
[fx] No, that’s not correct. Please try again.
[f*] Great!
[/qwiz]
6. Allele frequencies and fixed alleles in dogs
For another angle on allele frequencies, let’s think about dogs. If you buy a dog with a pedigree (a dog of a known breed), then you’re buying a certain look and disposition. You can count on this because dog breeds are controlled populations where the gene pool is closely guarded by dog owners who care about the breed. In other words, if you buy a Rhodesian Ridgeback, you can be assured that your new puppy had two parents who were both Rhodesian Ridgebacks. For all the traits that define the breed, these dogs are completely homozygous. Most of the defining alleles, in other words, are fixed and would have an allele frequency of 1.0 (or 100%) in these very artificial gene pools.
If your preference is for mutts, then your dog is probably heterozygous for many genes. As a result, when you breed two mutts, the offspring’s appearance is much less predictable.
7. Population Genetics and Allele Frequency Flashcards
[qdeck style=”width: 600px !important;” bold_text=”false” qrecord_id=”sciencemusicvideosMeister1961-Population Genetics and allele frequency (v2.0)”]
[h] Population Genetics and Allele Frequency Flashcards
[q] Define population genetics
[a] Population genetics is the study of how genes are distributed and change within a population.
[q] What’s a gene pool?
[a] A gene pool is the total set of all alleles for all the genes in a population?
[q] What’s a fixed allele?
[a] A fixed allele is an allele that is the only variant that exists for that gene in the population. A fixed allele is homozygous for all members of the population.
[q] Define allele frequency
[a] Allele frequency is a measure of how common an allele is in a population’s gene pool.
[q] A friend of yours is taking a 9th-grade biology class. They’ve just learned that achondroplasia is a dominant allele, and say “if achondroplasia is a dominant allele, shouldn’t everybody have achondroplasia?” Set them straight.
[a] You might say something like this. “I’m afraid that you’ve confused two concepts. The frequency of an allele has nothing to do with whether or not it’s dominant or recessive. Allele frequency is a function of the phenotype that the allele codes for. If the allele codes for a beneficial phenotype, then it’ll become common within a gene pool. If it codes for a harmful phenotype, then it will become less common.”
[x] [restart]
[/qdeck]
8. Allele Frequencies in Populations: Checking Understanding
[qwiz style=”width: 600px; min-height: 0px; border: 3px solid black;” qrecord_id=”sciencemusicvideosMeister1961-Allele Frequencies in Populations(v2.0)”]
[h]Quiz: Allele frequencies in populations
[q topic= “determining_allele_frequency”]Allele frequency is
[c]IHRoZSB0b3RhbCBudW1iZXIgb2YgaG9tb3p5Z291cyBpbmRpdmlkdWFscyBmb3VuZCBpbiBhIHBvcHVsYXRpb27igJlzIGdlbmUgcG9vbC4=[Qq]
[c]IFRoZSBudW1iZXIgb2YgZG9taW5hbnQgYWxsZWxlcyBmb3VuZCBpbiBhIGdlbmUgcG9vbC4=[Qq]
[c]IHRoZSBwZXJjZW50YWdlIG9yIGZyYWN0aW9uIG9mIGFsbCBhbGxlbGVzIGZvciBhIH NwZWNpZmljIGdlbmUgcmVwcmVzZW50ZWQgYnkgb25lIHNwZWNpZmljIGFsbGVsZS4=[Qq]
[f]IE5vLiBNZWFzdXJpbmcgdGhlIG51bWJlciBvZiBob21venlnb3RlcyB3aWxsIG1vdmUgeW91IHRvd2FyZCBmaWd1cmluZyBvdXQgdGhlIGFsbGVsZSBmcmVxdWVuY3ksIGJ1dCB0aGF04oCZcyBub3QgdGhlIGJlc3QgYW5zd2VyLiBBbGxlbGUgZnJlcXVlbmN5IGlzIHNpbXBseSBob3cgY29tbW9uIGFuIGFsbGVsZSBpcyBpbiBhIGdlbmUgcG9vbC4=[Qq]
[f]IE5vLiBNZWFzdXJpbmcgdGhlIG51bWJlciBvZiBkb21pbmFudCB3aWxsIG1vdmUgeW91IHZlcnkgY2xvc2UgdG8gZmlndXJpbmcgb3V0IHRoZSBhbGxlbGUgZnJlcXVlbmN5LCBidXQgdGhhdOKAmXMgbm90IHRoZSBiZXN0IGFuc3dlci4gQWxsZWxlIGZyZXF1ZW5jeSBpcyBzaW1wbHkgaG93IGNvbW1vbiBhbiBhbGxlbGUgaXMgaW4gYSBnZW5lIHBvb2wu[Qq]
[f]IFllcy4gQWxsZWxlIGZyZXF1ZW5jeSBpcyBzaW1wbHkgaG93IGNvbW1vbiBhbiBhbGxlbGUgaXMgaW4gYSBnZW5lIHBvb2wsIHJlcHJlc2VudGVkIGJ5IGEgcGVyY2VudGFnZSBvciBhIGZyYWN0aW9uLg==
Cg==[Qq]
[q topic= “determining_allele_frequency”]The letters below represent the alleles for a single gene that controls fur color in a population of mice. In this population, the frequency of the ‘a’ allele is
| aa | Aa | aa | Aa |
| Aa | aa | aa | aa |
| aa | Aa | aa | Aa |
[c]IDUwJQ==[Qq]
[c]IDE5LzI0LCBv ciA3OS4xNiU=[Qq]
[c]IDcvMTIgb3IgNTguMzMl[Qq]
[f]IE5vLiBJdCBsb29rcyBsaWtlIHlvdSBjb3VudGVkIG9ubHkgdGhlICYjODIyMDthJiM4MjIxOyBhbGxlbGUgaW4gaG9tb3p5Z291cyByZWNlc3NpdmVzICgmIzgyMjA7YWEmIzgyMjE7KS4gVG8gZ2V0IHRoZSBwcm9wZXIgZnJlcXVlbmN5LCB5b3UgaGF2ZSB0byBjb3VudCB0aGUgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZSBpbiB0aGUgaGV0ZXJvenlnb3RlcywgdG9vLiBSZWNvdW50IGFsbCB0aGUgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZXMsIGFuZCBkaXZpZGUgYnkgdGhlIHRvdGFsIG51bWJlciBvZiBhbGxlbGVzIGluIHRoaXMgcG9wdWxhdGlvbiAoMjQpLg==[Qq]
[f]IEV4YWN0bHkuIFRoZXJlIGFyZSAxOSAmIzgyMjA7YSYjODIyMTsgYWxsZWxlcyBvdXQgb2YgYSB0b3RhbCBvZiAyNCBhbGxlbGVzIGluIHRoaXMgcG9wdWxhdGlvbi4gVGhhdCBtZWFucyB0aGUgZnJlcXVlbmN5IGlzIDE5LzI0LCBvciA3OS4xNiU=[Qq]
[f]IE5vLiA3LzEyIGlzIHRoZSBmcmVxdWVuY3kgb2YgaG9tb3p5Z291cyByZWNlc3NpdmVzwqAgKCYjODIyMDthYSYjODIyMTspIGluIHRoaXMgcG9wdWxhdGlvbiBvZiAxMi4gVGhlIGZyZXF1ZW5jeSBvZiAmIzgyMjA7YSYjODIyMTsgaXMgZm91bmQgYnkgY291bnRpbmcgZXZlcnkgJiM4MjIwO2EmIzgyMjE7IGFsbGVsZSBhbmQgZGl2aWRpbmcgYnkgdGhlIHRvdGFsIG51bWJlciBvZiBhbGxlbGVzIGluIHRoZSBwb3B1bGF0aW9uICgyNCku
Cg==[Qq]
[q topic= “determining_allele_frequency”]The letters below represent the alleles for a single gene that controls fur color in a population of mice. In this population, the frequency of the dominant allele is
| aa | Aa | aa | Aa |
| Aa | aa | aa | aa |
| aa | Aa | aa | Aa |
[c]IDUvMTIsIG9yIDQxJQ==[Qq]
[c]IDIwLzI0LCBvciA4My4zMyU=[Qq]
[c]IDUvMjQsIG9yIG Fib3V0IDIxJQ==[Qq]
[f]IE5vLiA1LzEyIGlzIHRoZSBmcmVxdWVuY3kgb2YgaW5kaXZpZHVhbHMgd2hvIGhhdmUgdGhlIGRvbWluYW50IHBoZW5vdHlwZS4gVG8gZmluZCB0aGUgZnJlcXVlbmN5IG9mIHRoZSBkb21pbmFudCBhbGxlbGUgKCYjODIyMDtBJiM4MjIxOyksIHlvdSBoYXZlIHRvIGNvdW50IGV2ZXJ5ICYjODIyMDtBJiM4MjIxOyBhbGxlbGUsIGFuZCB0aGVuIGRpdmlkZSBpdCBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMgaW4gdGhlIHBvcHVsYXRpb24gKDI0KS4=[Qq]
[f]IE5vLiBJIHRoaW5rIHRoYXQgeW91IGNvbmZ1c2VkIHdoaWNoIGFsbGVsZSBpcyB0aGUgZG9taW5hbnQgYWxsZWxlIGFuZCB3aGljaCBvbmUgaXMgcmVjZXNzaXZlLiAmIzgyMjA7QSYjODIyMTsgaXMgdGhlIGRvbWluYW50IGFsbGVsZS4gQ291bnQgYWxsIHRoZSAmIzgyMjA7QSYjODIyMTtzLCBhbmQgZGl2aWRlIGJ5IHRoZSB0b3RhbCBudW1iZXIgb2YgYWxsZWxlcyB0byBnZXQgdGhlIGFuc3dlci4=[Qq]
[f]IFBlcmZlY3QuIFRoZXJlIGFyZSA1ICYjODIyMDtBJiM4MjIxOyBhbGxlbGVzLCBvdXQgb2YgYSB0b3RhbCBvZiAyNCBhbGxlbGVzIGluIHRoaXMgcG9wdWxhdGlvbi4gVGhhdCBtYWtlcyB0aGUgZnJlcXVlbmN5IG9mwqAgJiM4MjIwO0EmIzgyMjE7wqA1LzI0LCBvciBhYm91dCAyMSU=
Cg==[Qq]
[q topic= “determining_allele_frequency”]The letters below represent the alleles for a single gene that controls fur color in a population of mice. In this population, the frequency of the recessive allele is
| Aa | aa | aa | Aa | aa | aa | Aa | aa |
| Aa | aa | AA | Aa | Aa | aa | Aa | aa |
[c]IDIz[Qq]
[c]IDIzLzMyLCBv ciA3MS45JS4=[Qq]
[c]IDE2LzMyIG9yIDUwJQ==[Qq]
[f]IE5vLiBJdCBsb29rcyBsaWtlIHlvdSBjb3VudGVkIHRoZSBudW1iZXIgb2Yg4oCYYeKAmSBhbGxlbGVzIGNvcnJlY3RseSwgd2hpY2ggaXMgYSBnb29kIHN0YXJ0LiBCdXQg4oCYZnJlcXVlbmN54oCZIGlzIGFib3V0IHRoZSBwcm9wb3J0aW9uIG9mIGEgc3BlY2lmaWMgYWxsZWxlIGluIGEgZ2VuZSBwb29sLg==wqAgTm93LCBkaXZpZGUgdGhlIG51bWJlciBvZiByZWNlc3NpdmUgYWxsZWxlcyBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMgdG8gZ2V0IHRoZSBmcmVxdWVuY3kgb2YgJiM4MjIwO2EuJiM4MjIxOw==[Qq]
[f]IENvcnJlY3QuIFRoZXJlIGFyZSAyMyAmIzgyMjA7YSYjODIyMTsgYWxsZWxlcywgYW5kIDMyIGFsbGVsZXMgaW4gdG90YWwuIFRoZSBmcmVxdWVuY3kgb2YgJiM4MjIwO2EmIzgyMjE7IGluIHRoaXMgZ2VuZSBwb29sIGlzIDIzLzMyLCBvciA3MS45JQ==[Qq]
[f]IE5vLiBZb3UgZm9yZ290IHRvIGNvdW50IHRoZSAmIzgyMjA7YSYjODIyMTsgYWxsZWxlcyBpbiB0aGUgaGV0ZXJvenlnb3Rlcy4gQ291bnQgQUxMIG9mIHRoZSDigJhh4oCZIGFsbGVsZXMsIHRoZW4gZGl2aWRlIGJ5IHRoZSB0b3RhbCBudW1iZXIgb2YgYWxsZWxlcyAoMjQp
Cg==[Qq]
[q topic= “determining_allele_frequency”]The letters below represent the alleles for a single gene that controls fur color in a population of mice. In this population, the frequency of the dominant allele is
| Aa | aa | aa | Aa | aa | aa | Aa | aa |
| Aa | aa | AA | Aa | Aa | aa | Aa | aa |
[c]IDUwJQ==[Qq]
[c]IDIzLzMyLCBvciA3MS45JS4=[Qq]
[c]IDkvMzIgb3 IgMjguMSU=[Qq]
[f]IE5vLiBJdCBsb29rcyBsaWtlIHlvdSBjb3VudGVkIHRoZSBmcmVxdWVuY3kgb2YgaW5kaXZpZHVhbHMgd2l0aCBhIGRvbWluYW50IHBoZW5vdHlwZS4gV2hhdCB5b3UgbmVlZCB0byBkbyBpcyBjb3VudCBldmVyeSBpbnN0YW5jZSBvZiB0aGUgJiM4MjIwO0EmIzgyMjE7IGFsbGVsZSwgYW5kIGRpdmlkZSBieSB0aGUgdG90YWwgbnVtYmVyIG9mIGFsbGVsZXMgaW4gdGhlIHBvcHVsYXRpb24u[Qq]
[f]IE5vLiBZb3UgZmlndXJlZCBvdXQgdGhlIGZyZXF1ZW5jeSBvZiB0aGUgcmVjZXNzaXZlIGFsbGVsZSwgJiM4MjIwO2EuJiM4MjIxOyBOb3cgdXNlIHRoZSBzYW1lIG1ldGhvZCB0byBmaWd1cmUgb3V0IHRoZSBmcmVxdWVuY3kgb2YgdGhlIGRvbWluYW50IGFsbGVsZS4=[Qq]
[f]IFllcy4gVGhlcmUgYXJlIDkg4oCYQeKAmSBhbGxlbGVzLCBhbmQgMzIgYWxsZWxlcyBpbiB0b3RhbCwgZm9yIGEgZnJlcXVlbmN5IG9mIDI4LjEl
Cg==[Qq]
[q topic= “determining_allele_frequency”]If an allele is fixed in a population, then its frequency would be
[c]IDAsIG9yIDAl[Qq]
[c]IDAuNSwgb3IgNTAl[Qq]
[c]IDEuMCwgb3 IgMTAwJQ==[Qq]
[f]IE5vLiBJZiBhbiBhbGxlbGUgaXMgZml4ZWQsIHRoZW4gaXTigJlzIHRoZSBvbmx5IGFsbGVsZSBmb3IgdGhhdCBnZW5lIGluIHRoZSBwb3B1bGF0aW9uLiBBbiBhbGxlbGUgd2hvc2UgZnJlcXVlbmN5IGlzIDAgZG9lc27igJl0IGV4aXN0IGluIHRoZSBwb3B1bGF0aW9uLiBOZXh0IHRpbWUsIGNob29zZSBhbm90aGVyIGFuc3dlci4=[Qq]
[f]IE5vLiBJZiBhbiBhbGxlbGUgaXMgZml4ZWQsIHRoZW4gaXTigJlzIHRoZSBvbmx5IGFsbGVsZSBmb3IgdGhhdCBnZW5lIGluIHRoZSBwb3B1bGF0aW9uLiBBbiBhbGxlbGUgd2hvc2UgZnJlcXVlbmN5IGlzIDAuNSB3b3VsZCBtYWtlIHVwIGhhbGYgb2YgdGhlIGFsbGVsZXMgaW4gYSBwb3B1bGF0aW9uIGZvciBhIHNwZWNpZmljIGdlbmUuIE5leHQgdGltZSwgY2hvb3NlIGFub3RoZXIgYW5zd2VyLg==[Qq]
[f]IEV4YWN0bHkuIElmIGFuIGFsbGVsZSBpcyBmaXhlZCwgdGhlbiBpdOKAmXMgdGhlIG9ubHkgYWxsZWxlIGZvciB0aGF0IGdlbmUgaW4gdGhlIGdlbmUgcG9vbC4=wqAgaXRzIGZyZXF1ZW5jeSB3b3VsZCBiZSAxLjAsIG9yIDEwMCUu
Cg==[Qq]
[q topic= “determining_allele_frequency”]Which of the following is true about purebred dogs?
[c]IEZvciBtb3N0IG9mIHRoZSBnZW5lcyBpbiB0aGUgZG9nIGdlbm9tZSwgcHVyZWJyZWQgZG9ncyBhcmUgbW9yZSBoZXRlcm96eWdvdXMgdGhhbiBtdXR0cy4=[Qq]
[c]IFRoZXkgaGF2ZSBtYW55IG1vcmUgZml4 ZWQgYWxsZWxlcyB0aGFuIG11dHRzLg==[Qq]
[f]IE5vLiBQdXJlYnJlZCBkb2dzIGhhdmUgYmVlbiBicmVkIGZvciB0aGUgcHJlZGljdGFibGUgdHJhaXRzIG9mIHRoZWlyIGJyZWVkLiBGb3IgdGhlc2UgdHJhaXRzLCBtZW1iZXJzIG9mIGEgcHVyZWJyZWQgYnJlZWQgYXJlIG1vc3RseSBob21venlnb3VzLg==[Qq]
[f]IFllcy4gUHVyZWJyZWQgZG9ncyBoYXZlLCB0aHJvdWdoIHRoZSBwcm9jZXNzIG9mIHNlbGVjdGl2ZSBicmVlZGluZywgYmVjb21lIGV4dHJlbWVseSBob21venlnb3VzIGF0IG1hbnkgYWxsZWxlcywgbGVhZGluZyB0byBtYW55IGZpeGVkIGFsbGVsZXMgd2l0aGluIHRoZWlyIHBvcHVsYXRpb25zLg==
Cg==[Qq]
[q topic= “determining_allele_frequency”]A group of breeders is trying to create a new breed of dog. As they do, which of the following would you expect to be true?
[c]IEZvciBlYWNoIHRyYWl0IHRoYXQgdGhlIGJyZWVkZXJzIGFyZSB0cnlpbmcgdG8gZGVmaW5lLCB0aGUgZnJl cXVlbmN5IG9mIHRoZSBhbGxlbGVzIGZvciB0aGF0IHRyYWl0IHNob3VsZCBiZSBzdGVhZGlseSByaXNpbmcu[Qq]
[c]IEZvciBlYWNoIHRyYWl0IHRoYXQgdGhlIGJyZWVkZXJzIGFyZSB0cnlpbmcgdG8gZGVmaW5lLCB0aGUgZnJlcXVlbmN5IG9mIHRoZSBhbGxlbGVzIGZvciB0aGF0IHRyYWl0IHNob3VsZCBiZSBzdGVhZGlseSBmYWxsaW5nLg==[Qq]
[f]IFllcy4gQnJlZWRlcnMgd2lsbCBzZWxlY3QgZm9yIHRoZSBuZXcgcGhlbm90eXBlIHRoZXnigJlyZSB0cnlpbmcgdG8gY3JlYXRlLiBBcyB0aGV5IGRvLCB0aGUgZnJlcXVlbmN5IG9mIHRoZSBhbGxlbGVzIGZvciB0aG9zZSBwaGVub3R5cGVzIHdpbGwgc3RlYWRpbHkgcmlzZS4=[Qq]
[f]IE5vLiBJdOKAmXMgdGhlIG9wcG9zaXRlLiBCcmVlZGVycyB3aWxsIHNlbGVjdCBmb3IgdGhlIG5ldyBwaGVub3R5cGUgdGhleeKAmXJlIHRyeWluZyB0byBjcmVhdGUuIEFzIHRoZXkgZG8sIHdoYXQgd2lsbCBoYXBwZW4gdG8gdGhlIGZyZXF1ZW5jeSBvZiB0aGUgYWxsZWxlcyBmb3IgdGhvc2UgdHJhaXRzPw==
Cg==[Qq]
[q topic= “natural_selection_in_gene_pools”]True or false? In any population, the most common allele is the dominant allele.
[c]VHJ1ZQ==[Qq]
[c]RmFs c2U=[Qq]
[f]IE5vLiBUaGUgZnJlcXVlbmN5IG9mIGFuIGFsbGVsZSBoYXMgbm90aGluZyB0byBkbyB3aXRoIHdoZXRoZXIgaXTigJlzIGRvbWluYW50IG9yIHJlY2Vzc2l2ZS4=wqAgSnVzdCB0aGluayBhYm91dCB0aGUgZmFjdCB0aGF0IHNvbWUgZGlzZWFzZS1yZWxhdGVkIGFsbGVsZXMgYXJlIGRvbWluYW50LCB5ZXQgcmFyZSAobGlrZSB0aGUgYWxsZWxlIGZvciBhY2hvbmRyb3BsYXN0aWMgZHdhcmZpc20pLiBPciB0aGUgZmFjdCB0aGF0IGluIHRoZSBTY2FuZGluYXZpYW4gY291bnRyaWVzLCBzb21lIHBoZW5vdHlwZXMgY29udHJvbGxlZCBieSByZWNlc3NpdmUgYWxsZWxlcyAoYmx1ZSBleWVzLCBmb3IgZXhhbXBsZSkgYXJlIHRoZSBtb3N0IGNvbW1vbi4=[Qq]
[f]IENvcnJlY3QuIFRoZSBmcmVxdWVuY3kgb2YgYW4gYWxsZWxlIGhhcyBub3RoaW5nIHRvIGRvIHdpdGggd2hldGhlciBpdOKAmXMgZG9taW5hbnQgb3IgcmVjZXNzaXZlLiBSZWNlc3NpdmUgYWxsZWxlcyBjYW4gYmUgbW9yZSBjb21tb24gdGhhbiBkb21pbmFudCBhbGxlbGVzLiBJdCBhbGwgZGVwZW5kcyBvbiB0aGUgYWxsZWxlLCB0aGUgZXZvbHV0aW9uYXJ5IGhpc3Rvcnkgb2YgdGhlIHBvcHVsYXRpb24sIGFuZCBzZWxlY3RpdmUgcHJlc3N1cmVzIGZyb20gdGhlIGVudmlyb25tZW50Lg==[Qq]
[x]
[restart]
[/qwiz]
9. What’s next?
Proceed to Topics 7.4 -7.5, Part 2: The Hardy-Weinberg Equation, the next tutorial in AP Bio Topics 7.4 – 7.5 (Population Genetics).