Post a Comment. One way to study evolution is to study how the frequency of alleles in a population changes from generation to generation. In other words, you can ask What are the inheritance patterns of alleles, not just from two parental organisms, but also in a population? Mathematical models and computer simulations are tools used to explore the complexity of biological systems that might otherwise be difficult or impossible to study.
Several models can be applied to questions about evolution.
In this investigation, you will build a spreadsheet that models how a hypothetical gene pool changes from one generation to the next. The second part of the investigation asks you to generate your own questions regarding the evolution of allele frequencies in a population.
These models are available for free. This investigation also provides an opportunity for you to review concepts you might have studied previously, including natural selection as the major mechanism of evolution; the relationship among genotype, phenotype, and natural selection; and fundamentals of classic Mendelian genetics. This particular investigation provides a lab environment, guidance, and a problem designed to help you understand and develop the skill of modeling biological phenomena with computers.
There are dozens of computer models already built and available for free. The idea for this laboratory is for you to build your own from scratch.
To obtain the maximum benefit from this exercise, you should not do too much background preparation. As you build your model and explore it, you should develop a more thorough understanding of how genes behave in population. To help you begin, you might want to work with physical models of population genetics, such as simulations that your teacher can share with you. With these pencil-and-paper simulations, you can obtain some insights that may help you develop your computer model.
It is easy to understand how microscopes opened up an entire new world of biological understanding. For some, it is not as easy to see the value of mathematics to the study of biology, but, like the microscope, math and computers provide tools to explore the complexity of biology and biological systems — providing deeper insights and understanding of what makes living systems work. To explore how allele frequencies change in populations of organisms, you will first build a computer spreadsheet that models the changes in a hypothetical gene pool from one generation to the next.
You need a basic familiarity with spreadsheet operations to complete this lab successfully. You may have taken a course that introduced you to spreadsheets before. If so, that will be helpful, and you may want to try to design and. Otherwise, you may need more specific guidance from your teacher. In the second part of the investigation, you will use more sophisticated spreadsheet models or computer models to explore various aspects of evolution and alleles in populations.
To understand how these complex tools work and their limitations, you first need to build a model of your own. The real world is infinitely complicated. To penetrate that complexity using model building, you must learn to make reasonable, simplifying assumptions about complex processes. For example, climate change models or weather forecasting models are simplifications of very complex processes — more than can be accounted for with even the most powerful computer.
These models allow us to make predictions and test. By definition, any model is a simplification of the real world. For that reason, you need to constantly evaluate the assumptions you make as you build a model, as well as evaluate the results of the model with a critical eye.Technical Difficulties?
Please e-mail Our WebMaster. Here you will find copies of most of the labs and activities that we perform in class. Some are only available from the AP Lab book, so I cannot post those online. Get Adobe Acrobat Reader for free. She has given me permission to share it. Glucose -- print on many different colors of paper to symbolize different sugars.
Have students name each sugar with any name they want as long as it ends in -ose. Kimose is one of my favorites Students can get very creative! Water Drops large -- I print on blue paper to symbolize water. Water Drops small -- easier to use for building fats. I print on blue paper to symbolize water. Glycerol legal Glycerol letter -- in case you don't have legal size paper.
Unsaturated Fatty Acid legal -- print on different color paper than saturated fatty acid to accent difference. Unsaturated Fatty Acid letter -- in case you don't have legal size paper. Print on different color paper than saturated fatty acid to accent difference. Amino Acids -- I have been wanting to improve these a bit but I haven't had the time.
They are fine the way they are. Please use them.The Hardy-Weinberg equation was examined using beads representing dominant and recessive alleles as the model. The number of homozygous dominant, homozygous recessive, and heterozygous diploid models was recorded. To represent natural selection, the alleles from homozygous recessive individuals were removed from model gene pool after each trial.
After 6 trials, all recessive alleles had been removed, showing natural selection eliminating the recessive allele from the gene pool. Through this lab we explored the Hardy-Weinberg Law of Genetic Equilibrium and allele frequency within a population.
The Hardy-Weinberg Law of Genetic Equilibrium states the genetic variation in a population will remain constant from one generation to the next if the population is stable and in genetic equilibrium. The five conditions for a population to qualify for Hardy-Weinberg equilibrium are a large breeding population, random mating, no change in allelic frequency due to mutation, no immigration or emigration, no natural selection. The main objective of this lab was to explore how natural selection would affect a population under Hardy-Weinberg Equilibrium.
We hypothesized the recessive allele would be removed entirely from the population at the end of ten trials. We conducted our study in Mrs. We began by placing the 50 red beads, representing allele for fur dominantand 50 white beads, representing allele for no fur recessivein a container, shaking them up, and then pairing two beads together to create an offspring of rabbits.
At the beginning of this lab, we saw how the parent generation carried an equal number of F and f alleles. However, we began to see the number of recessive alleles, represented by the white balls, decrease rapidly, while the number of dominant alleles red balls stayed constant throughout the entirety of the experiment. For example, in the first generation after the parents, the ratio of homozygous dominant fur to heterozygous fur to homozygous recessive no fur wasin comparison with the ration of the previous generation where the ration was Eliminating the rabbits with no fur in the parent generation reduced the total allele count by 24, which made the chances of survival much more likely.
These chances are shown in the allele frequencies. At the beginning of the experiment parent generation the allele frequency was 0. However, as more and more f alleles were eliminated, the frequency for allele F increased. By the fifth generation of bunny children, allele F had a frequency of 1, since it was the only trait left to be shown in this population of bunnies.
Our hypothesis that it would take 10 generations for half the population to be homozygous dominant and the other half to be heterozygous was proven very wrong. The purpose of this lab was to test the evolution of rabbits within a small population. Knowing that the allele for naked bunnies f was recessive we knew that it would eventually die away. Only five out of the ten trials were needed for this process to complete.
We learned that through natural selection the recessive genes die away with time. Lab Bench Activity. You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account.
You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. Conclusion The purpose of this lab was to test the evolution of rabbits within a small population. Share this: Twitter Facebook. Like this: Like Loading Leave a Reply Cancel reply Enter your comment here Fill in your details below or click an icon to log in:.Any changes in the gene frequencies in the population over time can be detected.
The law essentially states that if no evolution is occurring, then an equilibrium of allele frequencies will remain in effect in each succeeding generation of sexually reproducing individuals.
In order for equilibrium to remain in effect i. No gene flow can occur i. Random mating must occur i. No selection can occur so that certain alleles are not selected for, or against. Obviously, the Hardy-Weinberg equilibrium cannot exist in real life.
Some or all of these types of forces all act on living populations at various times and evolution at some level occurs in all living organisms. The Hardy-Weinberg formulas allow us to detect some allele frequencies that change from generation to generation, thus allowing a simplified method of determining that evolution is occurring. However, for individuals who are unfamiliar with algebra, it takes some practice working problems before you get the hang of it.
Below I have provided a series of practice problems that you may wish to try out. The frequency of the "a" allele. The frequency of the "A" allele. The frequencies of the genotypes "AA" and "Aa. Sickle-cell anemia is an interesting genetic disease. Normal homozygous individials SS have normal blood cells that are easily infected with the malarial parasite.
Thus, many of these individuals become very ill from the parasite and many die. Individuals homozygous for the sickle-cell trait ss have red blood cells that readily collapse when deoxygenated. Although malaria cannot grow in these red blood cells, individuals often die because of the genetic defect.
However, individuals with the heterozygous condition Ss have some sickling of red blood cells, but generally not enough to cause mortality. In addition, malaria cannot survive well within these "partially defective" red blood cells. Thus, heterozygotes tend to survive better than either of the homozygous conditions. There are students in a class.
Ninety-six did well in the course whereas four blew it totally and received a grade of F. The frequency of the dominant allele.
AP Biology Lab 8 Hardy-Weinberg problems? (Includes the questions)?
The frequency of heterozygous individuals.Purpose: In this lab, you will :. Prelab questions :. The Hardy Weinberg principle describes a hypothetical population that is not evolving. To remain in equilibrium, these conditions must be met:.
For this exercise, you will use the class as a sample population to find the allele frequencies for PTC tasting. For a person expressing the dominant allele, T, PTC has a bitter taste. Data for Exercise A :. Allele Frequency Based on the H-W equation. Exercise B: Case Studies.
The class will represent a breeding population. In order to simulate random mating, choose another student at random. For this simulation, we will assume that gender an genotype are irrelevant to mate selection. Your initial genotype is therefore Aa.
Record this on your data chart. You will be given 2 cards. These are your gametes. One card will have A and the other will have a. Each parent will contribute 1 gamete to each child.
Data for Case 1.The Hardy-Weinberg Principle: Watch your Ps and Qs
Initial Class Frequencies:. Using the following equations, calculate p and q:. Total number of alleles in class.In fact, biological evolution is now defined as: changes in allele proportions within a population over time.
Models in this section explore various mechanisms that affect allele proportions in populations. This model is an agent-based population genetics simulation. The program contains the tools to conduct virtual experiments violating all the assumptions of Hardy-Weinberg theory small population, selection, mutation, migration, and non-random mating.
This model illustrates random genetic drift, bottleneck effects, and founder effects. Three incompletely dominant alleles exist in the simulated population red, yellow, blue with heterozygous individuals appearing as the blending of the two alleles. You can adjust the mainland population size and put it through a bottleneck.
Also, you can colonize two islands off of the coast of the mainland with a random subset of the mainland population. This model is an adaptation of the classic experiment conducted by Peter Buriwhich documented genetic drift in laboratory populations of Drosophila.
In the model, ten vials populations of flies are held at a constant population size and the proportions of a mutant allele are tracked over generations.
The population size and the initial allele proportion can be manipulated. Models are best viewed on large screens and landscape modes. Directions and background information are embedded in the model exercise.
Launch Model. Share this model with others. Directions — PDF. Toggle Sliding Bar Area.See All.
See All Free Gizmos. Set the initial percentages of three types of parrots in a population and track changes in genotype and allele frequency through several generations. Analyze population data to develop an understanding of the Hardy-Weinberg equilibrium.
Determine how initial allele percentages will affect the equilibrium state of the population. Best For: Biology.
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