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AP Biology 7.4 Population Genetics | If you've been watching, you know that the homework from the previous night
will be the warm-up for the next lesson. |
AP Biology 7.4 Population Genetics | So this is from the homework from 7.3. |
AP Biology 7.4 Population Genetics | Let's take a look at our data table and see what this is about first. |
AP Biology 7.4 Population Genetics | Okay, incidents of antibiotic-resistant patients admitted to ICU
from 1994 to 2000. |
AP Biology 7.4 Population Genetics | Okay, we have a list of antibiotics,
ciprofloxacin, genomyocin, ampicillin, and mipinam, tazobactam. |
AP Biology 7.4 Population Genetics | And we have the percent of all samples demonstrating antibiotic resistance in 2000. |
AP Biology 7.4 Population Genetics | And then an overall change in percent resistance to antibiotics from 1994 to 2000. |
AP Biology 7.4 Population Genetics | Okay, let's read the story. |
AP Biology 7.4 Population Genetics | To determine the likelihood that a patient with a bacterial infection
who is in the intensive care unit, the ICU, of a hospital
could be successfully treated with antibiotic therapies,
researchers investigated the frequency of antibiotic resistance in bacteria
isolated from patients in ICUs in the United States from 1994 to 2000. |
AP Biology 7.4 Population Genetics | The data from the study are shown in the table,
along with the overall change in the frequency of bacterial resistance
in patient samples from 1994 to 2000. |
AP Biology 7.4 Population Genetics | Okay, what is our job to do? |
AP Biology 7.4 Population Genetics | A patient was admitted to the ICU in December 2000
with an uncharacterized bacterial infection. |
AP Biology 7.4 Population Genetics | Based on the data from the study, identify the following. |
AP Biology 7.4 Population Genetics | The antibiotic that was most likely to be effective for treating the infection
and then identify, to identify here, the antibiotic that was least likely
to be effective for treating the infection. |
AP Biology 7.4 Population Genetics | I'll give you about 20 seconds to do that if you are just joining us for the first time. |
AP Biology 7.4 Population Genetics | Okay, I'll give you 10 more seconds. |
AP Biology 7.4 Population Genetics | Okay, let's see what the scoring guideline indicated. |
AP Biology 7.4 Population Genetics | All right, so there's two points here because you identified two
medications, two antibiotics, and when you identify,
it can be as simple as saying the word. |
AP Biology 7.4 Population Genetics | Okay, so if you put imipinem,
which is the most effective, and ampicillin is the least effective,
you got both of those points. |
AP Biology 7.4 Population Genetics | Okay, I'm going to go through this for a few more times in this amount of detail. |
AP Biology 7.4 Population Genetics | And then probably by the time we start reviewing, I'll start dropping this or
then just narrow it down to what topic we're going to be reviewing. |
AP Biology 7.4 Population Genetics | Okay, so the topic of tonight, we're doing population genetics,
and that falls under the unit evolution or natural selection. |
AP Biology 7.4 Population Genetics | And each topic has questions called learning objectives. |
AP Biology 7.4 Population Genetics | And this is what we need to be able to do. |
AP Biology 7.4 Population Genetics | And we need to know content in order to answer these questions. |
AP Biology 7.4 Population Genetics | That content is called essential knowledge. |
AP Biology 7.4 Population Genetics | Each topic also has an associated science skill. |
AP Biology 7.4 Population Genetics | And this is how we're going to show that we know the answer to the question,
the learning objective. |
AP Biology 7.4 Population Genetics | The science skill that is associated with population genetics is questions and methods. |
AP Biology 7.4 Population Genetics | And this includes a null hypothesis or an alternate hypothesis and predicting the
results of the experiment. |
AP Biology 7.4 Population Genetics | Today, we'll topic skill pair population
genetics with questions and methods. |
AP Biology 7.4 Population Genetics | OK, here's what you need to know. |
AP Biology 7.4 Population Genetics | All right, so
the learning objective explain how random
occurrences affect the genetic makeup of a population. |
AP Biology 7.4 Population Genetics | We're going to learn about mutations, genetic drift, two types. |
AP Biology 7.4 Population Genetics | We're going to talk about bottleneck. |
AP Biology 7.4 Population Genetics | And we're going to talk about founder effect. |
AP Biology 7.4 Population Genetics | And then we're going to talk about gene flow. |
AP Biology 7.4 Population Genetics | The first
occurrence that we're going to talk about is mutations. |
AP Biology 7.4 Population Genetics | Mutations are changes in DNA sequences. |
AP Biology 7.4 Population Genetics | They can happen spontaneously and replication and result from environmental
factors such as radiation or chemicals. |
AP Biology 7.4 Population Genetics | Mutations can result in a recessive disorder or a dominant disorder. |
AP Biology 7.4 Population Genetics | A change in the DNA sequence caused by
mutations may affect the structure and function of proteins. |
AP Biology 7.4 Population Genetics | Mutations result in genetic variation,
which provides phenotypes on which natural selection acts. |
AP Biology 7.4 Population Genetics | This changes the genetic makeup of a population over time. |
AP Biology 7.4 Population Genetics | The next
topic I want to talk about is genetic drift. |
AP Biology 7.4 Population Genetics | And we're going to talk about two examples of that. |
AP Biology 7.4 Population Genetics | We're going to do bottleneck and founder effect in just a moment. |
AP Biology 7.4 Population Genetics | All right. |
AP Biology 7.4 Population Genetics | So genetic drift is a non
selective process occurring in small populations. |
AP Biology 7.4 Population Genetics | The smaller the number of organisms,
the more likely the representation of an allele will change or disappear. |
AP Biology 7.4 Population Genetics | There are two types of genetic drift
that I'm going to talk about bottleneck and founder effect. |
AP Biology 7.4 Population Genetics | OK, so for bottleneck, we're going to talk about the great prairie chicken. |
AP Biology 7.4 Population Genetics | And I want to tell you the story. |
AP Biology 7.4 Population Genetics | I read some research articles to pull all this together in the mid to late
eighteen hundreds in the state of Illinois. |
AP Biology 7.4 Population Genetics | There were millions of great prairie chickens in 1993. |
AP Biology 7.4 Population Genetics | There are only 50. |
AP Biology 7.4 Population Genetics | The great prairie chickens lost natural
habitats of prairie lands because of human activity such as creating farmland. |
AP Biology 7.4 Population Genetics | This reduced population had lost genetic diversity and variation. |
AP Biology 7.4 Population Genetics | The genetic diversity of the great prairie
chickens had declined over the years to this bottleneck. |
AP Biology 7.4 Population Genetics | To prove there had been a decrease in the number of alleles,
researchers used the DNA of great prairie chicken specimens from a museum
as a control for the pre bottleneck alleles. |
AP Biology 7.4 Population Genetics | They extracted DNA from museum specimens
and chickens from the central Illinois and other surrounding areas. |
AP Biology 7.4 Population Genetics | They analyzed the DNA from the samples taken from the feather root. |
AP Biology 7.4 Population Genetics | And they looked at six loci for differences in the number of alleles. |
AP Biology 7.4 Population Genetics | To do this, they ran PCR and gel electrophoresis. |
AP Biology 7.4 Population Genetics | Their results indicated there were five missing alleles. |
AP Biology 7.4 Population Genetics | So genetic diversity had in fact decreased during human during. |
AP Biology 7.4 Population Genetics | Human active from during from human activity. |
AP Biology 7.4 Population Genetics | OK, here is the state of Illinois, and this is not to scale. |
AP Biology 7.4 Population Genetics | And these these these great prairie chickens do not represent any number. |
AP Biology 7.4 Population Genetics | This is just a
a representation of there was a lot of prairie land for them. |
AP Biology 7.4 Population Genetics | And there are a lot of great prairie chickens. |
AP Biology 7.4 Population Genetics | And then that was reduced and they were down to just 50 in 1993 of great prairie chickens. |
AP Biology 7.4 Population Genetics | So if I said some words that you didn't
understand or you were thinking about two alleles, I added this part to help you out. |
AP Biology 7.4 Population Genetics | OK, so here we have an homologous pair. |
AP Biology 7.4 Population Genetics | I'm going to get my mouse so I can I don't know if you can see that. |
AP Biology 7.4 Population Genetics | No, I think I better do it with my finger. |
AP Biology 7.4 Population Genetics | OK, so here's a homologous pair of chromosomes. |
AP Biology 7.4 Population Genetics | So this is one came from your mom and one came from your dad. |
AP Biology 7.4 Population Genetics | And so here is these dark bands. |
AP Biology 7.4 Population Genetics | Those are actually genes and they have a location and we're going to call that a loci. |
AP Biology 7.4 Population Genetics | And so if you like just like living on your street, OK, if this was your street,
then you would have an address on that street and that would be your location. |
AP Biology 7.4 Population Genetics | Right. |
AP Biology 7.4 Population Genetics | So that's the loci that we're talking about. |
AP Biology 7.4 Population Genetics | So you can have more than two alleles. |
AP Biology 7.4 Population Genetics | And they tested the great prairie chickens at six different loci. |
AP Biology 7.4 Population Genetics | And that means that probably on six different chromosomes, a particular area on each one. |
AP Biology 7.4 Population Genetics | So the number of alleles went from 22 pre
bottleneck to 17 post bottleneck. |
AP Biology 7.4 Population Genetics | They lost five alleles during this time. |
AP Biology 7.4 Population Genetics | All right, the next example is Founder Effect. |
AP Biology 7.4 Population Genetics | And
I'll share something with you when I get through talking about this. |
AP Biology 7.4 Population Genetics | OK, Founder Effect has to do with a small group of individuals leaving a population
and establishing a new small population. |
AP Biology 7.4 Population Genetics | This results in decreased variety of alleles carried to this new small population. |
AP Biology 7.4 Population Genetics | Their new gene pool is different from their original population. |
AP Biology 7.4 Population Genetics | One example of Founder Effect is polydactyly. |
AP Biology 7.4 Population Genetics | Polydactyly is a symptom of a few different syndromes. |
AP Biology 7.4 Population Genetics | Polydactyly means extra digits. |
AP Biology 7.4 Population Genetics | These syndromes are commonly found in the old order Amish of Pennsylvania. |
AP Biology 7.4 Population Genetics | Recessive genes are responsible for the traits of these disorders. |
AP Biology 7.4 Population Genetics | In 1750s to 1850s, a small group of Amish people came to America and settled in Pennsylvania. |
AP Biology 7.4 Population Genetics | They left Germany and other areas due to differences in religious ideas. |
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