CGS Instructor’s Manual v1 - Classical Geneticscgslab.com/cgs1/CGSmanual.pdf · CGS Instructor’s Manual v1.1 by Ben Adamczyk. March 2008 4 see which parents were used in each

CGS Instructor’s Manual v1.1 by Ben Adamczyk. March 2008 1

CGS Instructor’s Manual v1.1 March 2008

Table of contents: PART I – AN OVERVIEW OF THE PROGRAM ................................................................................... 1

WHAT IS CGS? ........................................................................................................................................... 1 STUDENT AND INSTRUCTOR ACCESS ........................................................................................................... 2 SAVING/LOADING ....................................................................................................................................... 2 STUDENT INTERFACE .................................................................................................................................. 3 STATISTICAL ANALYSIS ............................................................................................................................. 6

PART II –THE GENETICS BEHIND THE PROGRAM ........................................................................ 7

ORGANISMS ................................................................................................................................................ 7 MODES OF INHERITANCE ............................................................................................................................ 7 LINKED TRAITS ......................................................................................................................................... 11 HOW WILD POPULATIONS ARE GENERATED .............................................................................................. 12

PART III – HOW TO USE THE INSTRUCTOR INTERFACE ........................................................... 13

MANAGING STUDENT AND INSTRUCTOR ACCOUNTS: ................................................................................ 13 ACCOUNT SETTINGS: ................................................................................................................................ 14

PART IV – FREQUENTLY ASKED QUESTIONS ............................................................................... 19

Part I – An overview of the program What is CGS? CGS is software that facilitates an inquiry-based approach to teaching classical genetics. Students’ own questions and observations motivate the crosses that they perform, and statistical tests can be used to support or refute their hypotheses. Instructors can set the parameters for the populations that the students observe. Students can apply abstract genetics knowledge (Punnett square analysis, linkage, etc) to real-world scenarios. Similar inquiry-based labs have been carried out using live organisms (typically Drosophila), but the use of live organisms comes with many challenges for the instructor. Among these, time constraints can limit the number of generations that can be observed. A computer-based simulation is much easier to set up, and allows for many generations to be observed. CGS can supplement the use of live organisms, or can be used in place of live organisms. Test crosses can be performed within three model species that are used in modern genetics laboratories: Drosophila melanogaster (fruit fly), Arabidopsis thaliana (a small plant), or Mus musculus (house mouse).


There are many ways that CGS can be used, and the difficulty of CGS-based labs can be tailored depending on the students’ level of understanding (specific options are outlined below). CGS can be used by individual students, groups of students, or as a demonstration tool for instructors. You may set up a series of populations for your students, and have them present their findings in a paper or oral presentation. The program can randomize the specific phenotypes so that students will not be able to look up the “answers” on the internet. In the future, a forum may be available to allow instructors to share their own ideas. Student and instructor access Students can access CGS by going to www.cgslab.com and clicking on the student login link. Instructors can access the instructor settings by going to the same website and clicking the instructor login link. CGS requires a broadband internet connection and web browser with the Adobe Flash Player plug-in installed. Before a student can use the program, their instructor needs to provide them with a Course ID, and a Student Account that they can use to log in. A Course ID is given to each instructor who uses the program. A Student Account is an account that is created by the instructor for a group of students. When a student Logs in for the first time, they should click on “Collect new organisms” and enter a Course ID/Student Account. They are then asked to enter the names of their group members. By entering their names, the instructor can more easily retrieve lost student passwords and view information for each student (see Part III for more information). However, you can instruct your students to skip this step if you want. After entering their names, students are issued a password that they can use if they quit the program and want to resume where they left off. To load saved populations, students should click “Retrieve Saved Organisms” when starting the program, and then type in their password. Saving/Loading After CGS issues a student password, students should use this password if they need to log in again. If they instead re-enter the Course ID/Student Account, they will be issued a new password and they will not see the same organisms that they looked at previously. To save a population, students need to click the ‘Done’ button after they have finished examining the population. Make sure your students know to click on ‘Done’ to save their population before quitting the program.


This screen is only displayed when a student examines a population for the first time to inform them that they have just collected a new population of organisms from the wild. It also tells students that their organisms will only be saved when the ‘Done’ button is clicked. If the student quits the program before clicking the ‘Done’ button, their population will NOT be saved! If this happens, they will collect a different wild population the next time they log in. Student Interface The student interface was designed so that students would not have to read an instruction manual. A summary of how to use the student interface is posted on the CGS website for students to read if needed. The section below focuses on aspects of the student interface that students may not figure out immediately on their own. Most students will be able to quickly figure out how to breed their organisms. However, students often struggle at first with how to interpret and organize the data that they collect. There are several features that are included in CGS to help with this: 1. View All Data

By clicking the “View All Data” button on the right side of the screen, students can see a list of all crosses that were performed within the current population. They can also


see which parents were used in each cross, and see a summary of the progeny that were observed in each generation. This data can easily be exported to Word or any other text editor for easy note taking by using the button on the top of the window.

2. Sort/View

Students can view their organisms either as pictures, or as symbols that represent phenotypes or sex. Organisms can also be sorted by these characteristics. Each organism is automatically assigned a number, so students can track the individuals that were used in their crosses. When a population has more than one independent trait segregating, students also have the option to sort by all traits. This will arrange the organisms according to each phenotypic class. Students can also adjust the size of the organism icons using the slider on the lower right side of the screen. Depending on how the organisms are sorted, it may be helpful to shrink the icons to see more organisms at a time.


3. Note taking

In the ‘Analysis’ window, a student can add their own notes for each generation that they create. These notes are saved along with the organisms. Additionally, if notes have been taken, they will be displayed in the “View all data” window. This makes it easy to export all data and notes out of the program and into a text editor.

4. Statistics

CGS can perform chi squared statistical tests (see below). Students who use this feature need to understand hypothesis testing and know what their expected ratios are.


Statistical Analysis In the ‘Stats’ window, students can perform a chi squared test on the organisms contained within that generation. Example: A student crosses two Drosophila flies from Vial 1 to generate the progeny in Vial 2. She expected to see a 1:1 ratio of ebony body and yellow body flies, and observes 45 ebony and 58 yellow. Was her 1:1 prediction correct? Are the observed deviations from 1:1 due to chance alone? Or is a 1:1 ratio statistically unlikely given these numbers? To answer this, she would select the trait she wants to analyze (Body color), enter her expected ratio (1:1), and press ‘Calculate’. CGS calculates that given these 103 offspring, you would expect 51.5 ebony and 51.5 yellow flies. The Chi squared value is 1.64, and the p value is 0.2. Since the p value is greater than 0.05, you cannot reject the null hypothesis (the null hypothesis is that there is a 1:1 ratio). This test supports that the deviation you see from a perfect 1:1 ratio could be due to chance alone. If the p value was less than 0.05, you would reject your hypothesis. *This can be confusing to many biologists, who usually try to REJECT the null hypothesis. For example, a researcher typically wants to show that their experimental data set is significantly DIFFERENT from the control data set. But here, we want to show that the expected and observed ratios are NOT significantly different. Also note that in CGS, organisms can be crossed multiple times, so it is easy to repeat a cross and perform additional chi squared tests.


Part II –The genetics behind the program Organisms Arabidopsis has some special characteristics relative to the other organisms in CGS. Because of this, there are special considerations to make when dealing with Arabidopsis populations:

- Arabidopsis is self-compatible (one individual can reproduce on its own) - Arabidopsis does not contain sex chromosomes - The first plant that is added to a cross is considered to be the “female.” This

means that the female gamete is derived from this plant. The second plant is the pollen donor in the cross. This is only important if students are testing for gamete lethality (see below for lethality options that can be used).

- When one plant is added to the crossing box, there is an option for “Self cross.” By clicking this button, both male and female gametes are derived from this plant.

- Note: self crossing is a very quick and easy way for students to establish true-breeding lines for test crosses (you may want to point this out to them).

For Drosophila, human, and mouse populations, CGS will not allow two males or two females to be crossed. In any population, no more than two individuals can be added to a cross. Modes of inheritance The following modes of inheritance are possible in the current version of CGS (some are not available for Arabidopsis because it does not contain sex chromosomes): Autosomal Dominant/Recessive The trait is encoded by a single genetic locus with two segregating alleles: One dominant (A) and one recessive (a). The locus is not on a sex chromosome, and is not linked to any other trait unless specified.

Cross Progeny probabilities AA x AA = 100% AA AA x aa = 100% Aa Aa x Aa = 50% Aa, 25% AA, 25% aa Aa x AA = 50% Aa, 50% AA Aa x aa = 50% Aa, 50% aa aa x aa = 100% aa

Autosomal Codominance This mode is the same as Autosomal Dominant/Recessive, except that neither allele is dominant or recessive and heterozygous individuals have a distinct phenotype.


X-linked Dominant/Recessive The trait is encoded by a single genetic locus with two segregating alleles: One dominant (A) and one recessive (a). The locus is located on the X-chromosome, and is not linked to any other trait unless specified.

Cross Progeny probabilities AA x AY = male(100% AY), female(100% AA) AA x aY = male(100% AY), female(100% Aa) Aa x AY = male(50% AY, 50% aY), female(50% Aa, 50% AA) Aa x aY = male(50% AY, 50% aY), female(50% Aa, 50% aa) aa x AY = male(100% aY), female(100% Aa) aa x aY = male(100% aY), female(100% aa)

X-linked Codominance This is the same as X-linked dominant/recessive, except that heterozygous females (two copies of the X-chromosome) experience a distinct phenotype relative to females that are homozygous for either of the two alleles. Males will be segregating with two phenotypes (because they only have one X-chromosome), and females will be segregating with three phenotypes. Y-linked The trait is encoded by a single genetic locus that has two alleles and is located on the Y chromosome. Phenotypes will be segregating between the males in the population, while females will have a third phenotype that does not segregate. Not heritable The trait can’t be explained by a simple single locus model. The phenotypes could be caused by a complicated combination of loci, or environmental variables that the researcher may not have accounted for. Some examples could be temperature, age of the parents, breeding conditions, lighting conditions, chemical contamination, etc. Students should be able to rule out all of their known modes of inheritance before determining that their observations can’t be explained by a single genetic locus. When a cross is performed, CGS randomly chooses between two phenotypes for each offspring (with a different random bias for each generation). Autosomal Dominant/Recessive (AA lethal) This mode is the same as Autosomal Dominant/Recessive, except that individuals that are homozygous for the dominant allele are embryo-lethal. Since they are embryo-lethal, they are not observed. This causes the ratio of progeny to be skewed, and it also makes it impossible to establish a true-breeding line with the dominant allele.


Autosomal Codominance (AA or BB lethal) This mode is the same as Autosomal Codominance, except that individuals that are homozygous for one of the alleles is embryo-lethal. So individuals can only have one of two possible genotypes: AA or AB (BB is embryo-lethal). Students will realize that true-breeding lines cannot be established, and will need to analyze the ratios of the offspring to determine that certain homozygotes are lethal. Autosomal (Male gametophtye 'A' lethal) This mode is similar to Autosomal Dominant/Recessive except that the dominant (A) allele will not be transmitted through the male gametophyte. The male donor of the cross will always donate the ‘a’ allele. Students will need to set up reciprocal crosses to determine that the defect is specific only to the male gametophyte. If this mode is used, you may want to warn students, or have a discussion about how they could spot a gametophytic lethal. Autosomal (Female gamotophyte 'A' lethal) This mode is similar to Autosomal (Male gametophtye 'A' lethal), but the female gametophyte is lethal. The female donor of the cross will always donate the ‘a’ allele. Random: Any possibility CGS will randomly assign one of the following when a new wild population is created (Sex-linked modes are not used for Arabidopsis): Autosomal Dominant/Recessive Autosomal Codominance X-linked Dominant/Recessive X-linked Codominance Y-linked Not heritable Autosomal Dominant/Recessive (AA lethal) Autosomal Codominance (AA or BB lethal) Autosomal (Male gametophtye 'A' lethal) Autosomal (Female gamotophyte 'A' lethal)

Random: No lethality CGS will randomly assign one of the following when a new wild population is created (Sex-linked modes are not used for Arabidopsis): Autosomal Dominant/Recessive Autosomal Codominance X-linked Dominant/Recessive X-linked Codominance Y-linked Not heritable


Random: Heritable without lethality CGS will randomly assign one of the following when a new wild population is created (Sex-linked modes are not used for Arabidopsis): Autosomal Dominant/Recessive Autosomal Codominance X-linked Dominant/Recessive X-linked Codominance Y-linked Random: Autosomal (Possible Codominance) CGS will randomly assign either Autodomal Dominant/Recessive or Autosomal Codominance when a new wild population is created. Random: Autosomal or X-Linked CGS will randomly assign either Autosomal Dominant/Recessive or X-linked Dominant/Recessive when a new wild population is created. This option is not available for Arabidopsis. Random: X-Linked or Y-linked CGS will randomly assign either X-linked or Y-linked when a new wild population is created. This option is not available for Arabidopsis. Random: Male or Female Gametophyte lethal CGS will randomly assign either Autosomal (Male gametophtye 'A' lethal) or Autosomal (Female gamotophyte 'A' lethal) when a new wild population is created.


Linked traits CGS allows two traits to be linked to an autosome, or to the X-chromosome. Loci can be linked with a recombination frequency between 0% and 45% (50% is not distinguishable from non-linked loci). When multiple traits are segregating in a population, you may want to have your students determine whether the traits are linked, and at what recombination frequency. While you can create a population with up to four independent traits, CGS will not allow you to link more than two traits to the same chromosome. Example: Traits linked to an autosome Consider the cross outlined below for an example of a cross between two organisms with linked (0% recombination frequency) autosomal loci (AaBb x AaBb):

It is important to note that not all flies in the wild population will have the same alleles linked together. For example, some flies may have AB linked, while others may have Ab or ab or aB linked. Students need to establish inbreeding lines to determine which alleles are linked in the flies that they are crossing. Students will get confused if they keep introducing new flies from the wild population into their crosses because they may be bringing in new linked pairs. *Note: The best strategy for students (you might discuss it ahead of time) is to cross a homozygous recessive individual (aabb) to a double heterozygous individual (AaBb). If they don’t see a 1:1:1:1 ratio in their phenotypes, they can determine which alleles are linked. They can also use this ratio to calculate recombination frequency.


How wild populations are generated This section is a behind-the-scenes look at how CGS “collects” wild populations. - Every population starts with 100 flies (or another organism)

o The premise being that you went out and collected 100 wild flies and brought them back to the lab for further investigation

- Each fly has a 50% chance of being male or female o The premise being that you were unbiased in your fly collecting

- A random number is generated between 0.1 and 0.9 for each trait within the population. Each fly is assigned a random number between 0 and 1 for each trait. If the fly’s random number is less than the population’s number, then the fly will have the dominant phenotype. Otherwise it will have the recessive phenotype.

o The premise being that selection/inbreeding/unknown factors can play into whether a dominant/recessive phenotype is more prevalent in a population. Students should not be able to infer any information about a possible mode of inheritance based on the ratios within the wild population without crossing.

- Genotypes are determined for each individual in the initial population AFTER the phenotypes have been assigned. This assignment depends on the mode of inheritance for the population:

o Autosomal : Recessive-phenotype flies are assigned a genotype of aa. Dominant-phenotype flies are assigned a genotype of either AA or Aa. A random number determines this with a 50% chance.

o Sex-linked: Recessive-phenotype males are assigned a genotype of aY, and dominant-phenotype males are assigned the genotype AY. Recessive-phenotype females are assigned the genotype aa, and dominant-phenotype females are assigned to either AA or Aa with a 50% chance for either.

o Codominance: A random number is generated between 0 and 1 for each fly, along with the random number between 0.1 and 0.9 that is generated for the population. This creates three ranges between 0 and 1. A third random number between 0 and 1 is generated for each fly. If this number is between zero and the first random number, it is assigned a genotype of aa and recessive phenotype. If it is between the two random numbers, it is assigned a genotype of AA dominant phenotype. If it is between the second random number and one it is assigned a genotype of Aa and the codominant phenotype. Depending on the random numbers selected, it is possible that only two of the three phenotypes will be present in the initial population.

o Environmental: Phenotypes are assigned as in the autosomal scenario, but are not assigned genotypes.


Part III – How to use the instructor interface Go to www.cgslab.com to access the instructor login link. You need your Course ID and instructor password to access the instructor settings. Managing student and instructor accounts: 1. New Student Account Entry. To create a new student account, enter a name for the

account here and click ‘New’. You will not be able to use an account name that has already been saved to the saved accounts list (2).

2. Saved Accounts List. All of your saved accounts are displayed here. To display

your settings for a saved account, click on the account. The settings are displayed in the settings window (3). To edit an existing account, click on the account to edit, then click the ‘Edit’ button.

3. Settings Window. There are two types of settings that are displayed in the Settings

window: Account settings and individual student settings. By clicking on a saved account, you can display the settings for that account. By clicking on a student login from the student list (4), you can display the settings for a specific student login.

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4. Student List. After you have clicked on an account from your saved account list (2), you will see a list of students who have logged in to this account. A list of student names and passwords are displayed. If you click on an entry in the list, the settings for that student login are displayed in the settings window (3). Since traits can be randomized within a saved account, this allows you to see the specific settings for each student.

5. Show All Students. Clicking this button will allow you to see a list of all students

who have logged into your accounts. Along with passwords and names for each student, you will also see which saved account was used by each student. Clicking on a saved account (2) will bring back a list of students specific to that account.

6. Logout. This will take you back to the login screen. Account settings: 7. Number of Populations. You may create up to ten populations for your students to

explore. To change the number of populations in this account, move the slider to the number you want. As you move the slider, a population button will appear on the left side of the screen (8) for each population in the account.

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8. Populations Buttons. Each population will have a button on the left side of the screen. To view or change the settings for a population, click on its button.

9. Population Name. You may enter a name for each population in your account. Each

population is given a number by default, but you can choose any name you want for each population. After renaming a population, the population buttons will reflect the new name you have given.

10. Organism Menu. After choosing a population to edit, select an organism for that

population. There are four options: Arabidopsis, Drosophila, mouse, or human. CGS handles Drosophila, mouse, and human populations similarly, with the only difference being the traits that the program suggests. When Arabidopsis is selected, some options will change since Arabidopsis does not contain sex chromosomes (see below).

11. Show Genotypes. By default this box is unchecked, and it is recommended that it

remain unchecked under most circumstances. If this is selected, students will be able to see the genotypes (in addition to phenotypes) for each organism. This makes the simulation trivial for most students.

12. Offspring per Generation. When Drosophila, mouse, or human are selected, you

can enter a range for the number of progeny that are created for each generation. When Arabidopsis is selected, you can enter a number of seeds that are planted for each generation. It is up to the instructor to designate an appropriate range. For example, creating a human population with 100 progeny per generation will help students with statistical analysis, but it wouldn’t reflect reality. Recommended ranges are: Drosophila (50-150), mouse (10-50), human (5-10), Arabidopsis (100).

13. Number of Traits. Each population can have up to four independent traits. Move

the slider to change the number of traits. As this number is changed, the number of trait tabs below will change. When a population contains more than one trait, additional options are displayed for linking traits on the same chromosome.


14. Trait tabs. A tab is created for each trait in your population. If a population contains

only one trait, there will only be one trait tab. When choosing from the genetics options that are specific to a particular trait, be sure that the correct trait tab is highlighted.

15. Mode of Inheritance. A full list of modes of inheritance is given above for each

organism. By choosing a random mode of inheritance, CGS will randomly pick a mode each time a new student logs into the account. This way different students who log in to the same account may get different answers (see #4 above for how to see the answers for each student). The mode of inheritance that is chosen may affect other options that are available. For example, if you make a trait nonheritable, you will not be able to link it to the same chromosome as another trait.

16. Trait Menu. The options that are available here are dependent on the organism that

is selected. Each organism comes with a list of suggested traits to choose from. If you don’t like these traits, you can enter any trait you want by typing it into the box. You can also select <Random> from the drop-down menu to have CGS pick a trait and phenotypes randomly each time a new student logs into the account. If you choose a specific trait, you can enter specific phenotypes for the trait (18), and choose whether you want to randomize the dominant and recessive phenotypes (17).

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17. Randomize Phenotypes. This option is only displayed when a trait other than <Random> is chosen from the trait menu. By checking this box, the dominant and recessive traits are randomized each time a new student logs in. This can prevent cheating because students who use the same account may get different answers. By leaving this box unchecked, students should all get the same answer for the specified trait.

18. Phenotype selection. This option is only displayed when a trait other than

<Random> is chosen from the trait menu. If you do not like the suggested phenotypes that are given, you can type your own phenotypes here. (Note: You can also type your own trait by typing it into the trait drop-down menu)

19. Linkage menu. This option is only displayed when there is more than one trait in a

population, and the options that are available depend on the number of traits. For example, if a population has two traits and the “Trait 1” tab is selected, there will be an option to link the current trait with “Trait 2” on the same chromosome. You can link two traits to the same autosome or sex chromosome; however, if two traits have incompatible modes of inheritance, a warning will be displayed and you will not be able to link the traits to the same chromosome (you cannot link a trait on the X-chromosome with an autosomal trait). While you can have up to four independent traits segregating in a population, only two traits can be linked to the same chromosome. When two traits are linked, you will be able to choose the

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recombination frequency (20). See additional notes above for common problems students have with linked traits.

20. Recombination frequency. This option is only displayed when two traits are linked

in a population. This is the probability for recombination between two linked loci. For example, if two traits are linked with a 10% recombination frequency, each maternal gamete has a 10% chance of carrying a recombinant chromosome, and each paternal gamete will have a 10% chance of carrying a recombinant chromosome. Clever students should be able to set up their crosses in a way that allows them to calculate the recombination frequency.

21. Confirm Button. Click here to review your settings before saving them. 22. Cancel Button. Click here to cancel any changes without saving, and return to the

main menu. 23. Confirmation Window. You can review your settings before saving them. You can

also copy and paste from this window if you want to take notes or print them for your records.

24. Edit Button. Click here to go back to the previous screen to make changes. 25. Save Button. Any changes you made are not saved until you click here.

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Part IV – Frequently Asked Questions This section is also publicly available on the CGS website What is CGS? CGS is a computer program that allows biology and genetics students to apply lessons in Mendelian genetics to real-world scenarios. CGS can be used as a primary laboratory module for introductory biology or genetics courses, or as a supplement to a hands-on genetics module with real organisms. There are several advantages to using a computer simulation to learn genetics, most importantly: 1. Students can examine many generations of genetic inheritance without the time restrictions that are inherent with living organisms. 2. A computer simulation is inexpensive and does not require a lot of resources. 3. No organisms are created or destroyed in the computer simulation. CGS offers three model organisms for analysis: Drosophila, Arabidopsis, or Mouse. Is CGS similar to GCK? CGS has many advantages over GCK (Bioquest, 1994) and can run on modern PC or Mac hardware. CGS is not affiliated with Bioquest. How do I use CGS? Students and instructors can access the program by going to www.cgslab.com. CGS is web-based. This offers several advantages, mainly: 1. Students can access the program from outside of class if needed. 2. Instructors can quickly set up the program for use on multiple computers. 3. Instructors can easily access all student information from one computer. How are instructor accounts obtained? Instructors who are interested in using CGS for their course should send a request to the email address above. Instructor accounts are only given to teachers and course coordinators, and are not given to students. Even if you do not have an account, you can try out the student interface by going to www.cgslab.com/demo. Can CGS be used without an internet connection? A stand-alone version of CGS can be made for Windows or Mac if there is interest. If this is something you would like to see, please send an email to the address above. How can CGS be customized?


CGS allows an instructor to create populations with specific phenotypes and modes of inheritance for students to analyze. Alternatively, CGS can randomize these settings. The first step is to create a new student account. First, log in and enter a new account name and press the 'New' button to proceed to the settings screen. The genetic properties for each population can be selected as shown in the examples below. Use the slider on the left side of the screen to choose the number of populations to create. There can be up to 10 independent populations created for each student account.

Up to four independent segregating traits can be created per population. For each individual trait, a specific mode of inheritance can be selected from the drop-down menu, or a mode can be randomly assigned. Traits can be linked to the same chromosome with a specified recombination frequency by using the drop-down menus.

CGS can randomize the mode of inheritance and phenotypes between students who log in with the same student account. This way, a small number of accounts can be sufficient for a large group of


students. Instructors can log in and access the "answers" for each student who has accessed their accounts.

How do students access the program?

To use CGS, students will need to know their instructor's "Course ID" and the "Student Account" that has been assigned to them. Students are given a password when they first log in. This password will allow them to retrieve their organisms if they quit and want to continue at a later time.

How can I access the details for each student?

From the instructor menu, click on a student's name to get information about which populations the student has examined, which phenotypes are dominant/recessive, the modes of inheritance for each population, etc.

Where can I get more information? Questions or suggestions about CGS can be sent to [email protected].

Documents

CGS Instructor’s Manual v1 - Classical Geneticscgslab.com/cgs1/CGSmanual.pdf · CGS Instructor’s Manual v1.1 by Ben Adamczyk. March 2008 4 see which parents were used in each