Activity 9: Genetic Analysis

Activity 9: Genetic Analysis


Don't use plagiarized sources. Get Your Custom Essay on
Activity 9: Genetic Analysis
Just from $5/Page
Order Essay

Dates available: This is an ONLINE lab. You will need a browser and Internet access. Each student works independently.  Upload your file in PDF format.


Evaluation: Report (20 points) should be uploaded in the Assignments section on D2L in PDF format by Friday April 17th at 11:59pm. Questions that require answers are highlighted. Questions on this lab may be included in future tests.


Objectives: Part 1:  Apply knowledge of genetic principles and statistics to analyze a cross in corn

  • Part 2: To simulate the diagnosis of sickle cell disease with DNA restriction analysis.

PART 1: Monohybrid Cross in Corn


You will study the inheritance of a character (kernel color) that has two alternatives (purple and yellow).


The corn you will analyze was produced by crossing two true-breeding (homozygous) individuals (the P generation), one purple and one yellow, to produce the F1 generation. Two individuals from the F1 then served as parents to produce the F2 generation. Each of the kernels you will count is a single member of the F2 generation.



P:                     Homozygous purple              x                 Homozygous yellow


F1:                                           purple              x          purple



What color is dominant? How do you know?








We will use the letter B for the dominant allele and b for the recessive. Fill the following table with the proper symbol.


Gene: kernel color                                    purple ______

2 alleles

Yellow _______








With this information, complete the genotype and gametes of all the individuals in the previous cross :



P:                     Homozygous purple              x                 Homozygous yellow

Genotype              _________                                                 __________









F1:                                           purple              x          purple (just like the other F1)

Genotype                             _________                      __________







Now, you are going to predict the expected genotypic and phenotypic ratios by filling a Punnett square


Gametes from one F1 parent



____                        ____


















Gametes                 ____

From the

Other F1







List all the different genotypes that resulted from the Punnett square and next to them write the corresponding phenotype.


GENOTYPE                           PHENOTYPE


BB                               ……………………..


Bb                               ……………………..


bb                                ……………………..





What are the phenotypic frequencies among the offspring of the Punnett square?


____ purple   :    _____  yellow

4                           4


These are your expected phenotypic frequencies. You will use them below.


Now, you are going to count the F2 from a particular cross and you will determine if that cross follows Mendel’s principles.


For the following corn, score at 4 rows for color (purple or yellow). Record your results in the table below.



You are going to estimate how far your observed values are from your expected values by calculating a χ 2 (chi square). The smaller your χ2, the smaller the deviations.  You will work with one decimal place. Show all your work!


NULL HYPOTHESIS: there are no significant differences between the observed numbers of purple and yellow kernels and the ones predicted by Mendel’s principles.


  Purple Yellow Total # of kernels
Observed (o)*      
Expected (e) **      
Difference (o-e)      
Difference squared (o-e)2      
(o-e)2 / (e)      
Σ ((o-e)2 /e) =




*Observed: what you counted

**Expected: you will calculate this numbers by multiplying the total number of kernels counted by the expected phenotypic frequency of each class. The expected phenotypic frequencies are the ones you estimated above. If you did this correctly, the observed and expected totals should be the same.

Write your χ2 in the box:                                  χ2 =



Determine the degrees of freedom (df).The degrees of freedom are calculated as the one less than the number of categories (in this case, flavors). (df = n-1). Record your df below.

df =



Compare your χ2 with the critical value provided by a χ2 distribution statistical table, reproduced below.


Chi-Square Table

to obtain the critical value

Degrees of Freedom Probability


1 3.84
2 5.99
3 7.82
4 9.49
5 11.07


Critical value =




Compare the χ2 value you calculated with critical value from the table.


  • If your calculated χ2 is larger than the critical value, the deviations you see are too large to be explained by chance alone. There is a significant difference between the observed and expected values and you must reject the null hypothesis.


  • If your calculated χ2 is smaller than the critical value, the deviations you see can be explained by chance alone. There is no significant difference between the observed and expected values and you fail to reject the null hypothesis. (Scientist are always cautious and never, ever, ever “accept” anything)



  1. Based on your individual sample, do you “reject” or “fail to reject” the null hypothesis? Why?


  1. If you rejected your null hypothesis, what might be some explanations for your







  1. Is the trait “kernel color” inherited as you expected by Mendelian principles? Justify your answer.


  1. Even if the differences between observed and expected values are not significant, the values themselves are probably different. Explain why the two sets of values are not exactly the same? (think about what happens when you flip a coin)


  1. Do you think your results would have been closer if you only counted one row? Explain


  1. Do you think your results would have been closer if you counted ten times more kernels? Why or why not? (Assume that you count is equally accurate)



PART 2: Diagnosis of sickle cell disease with DNA restriction analysis.


Sickle Cell Disease

Sickle cell disease (SCD), also known as sickle cell anemia, was the first genetic disease to be characterized at the molecular level. The mutation responsible for sickle cell anemia is small—just ONE nucleotide (one letter) of DNA out of the three billion in each human cell. Yet it is enough to change the chemical properties of the hemoglobin, the iron and protein complex that carries oxygen within red blood cells.


There are two versions of the hemoglobin gene: A and S. Individuals with two normal A genes (AA) have normal hemoglobin, and therefore normal RBCs. Those with two mutant S genes (SS) develop SCD. Those who have one of each (AS), often called “carriers”, produce both normal and abnormal hemoglobin. Carriers (AS) are usually healthy, but they may suffer some symptoms of sickle cell anemia under conditions of low blood oxygen, such as high elevation.


DNA Restriction Analysis as a Diagnostic Tool for SCD.

In 1978, Yuet Wai Kan and Andrees Dozy of the University of California-San Francisco showed that the restriction enzyme Mst II, which cuts normal hemoglobin DNA at a particular site, will not recognize (and therefore will not cut) DNA that contains the sickle cell mutation. Thus, the DNA from normal homozygous individuals (AA), heterozygous carriers of the trait (AS), and homozygous sickle cell patients (SS) produces different sizes of restriction fragments when cut with Mst II.


During this imaginary lab we will simulate the diagnosis of SCD by DNA gel electrophoresis. The DNA samples of four members of a family have been run in a gel. Their DNA has been “cut” by the Mst II restriction enzyme.  Known samples will also be run for comparison.









The lanes are coded in the following manner:


Mother M
Father F
Teenager T
Newborn N
Normal Hemoglobin A
Sickle Cell Hemoglobin S



Here is the gel:                      M       F        T       N     A        S



(-)        Wells















Interpret the results of the tests:

Which family members have the sickle cell genotype (SS)?


Which family members have the carrier genotype (AS)?


Which family members have the normal genotype (AA)?


Each child inherits only ONE copy of the gene with each parent. To estimate the chances for two carrier parents “AS” to have a child with sickle cell, you must construct a “Punnett Square”, which has the gametes made by each parent separate.

Gametes made by Mom

  A S


Made by










Fill the square and estimate de following probabilities:


Probability that this couple will have a normal child (AA): ____________  out of four


Probability that this couple will have child with sickle cell (SS): ____________  out of four


Probability that this couple will have a carrier child (AS): ____________  out of four



Imagine that you are a genetic counselor. Explain to the family (in the form of a letter addressed to the parents) what the results of their tests show based on the information you obtained from the gel and your Punnett square for all members of the family. In addition explain what their options are both now and in the future based on the probabilities that you just calculated and some research. Use an understanding tone, and be aware of sensitive issues.



Should genetic defects that cause hereditary problems be diagnosed before birth? Why or


Finally, you will do a little bit of internet research and answer the following questions in your own words.


  1. What is the job of a genetic counselor?
  2. What degree is necessary to work as a genetic counselor?
  3. Where can a person study to become a genetic counselor?
  4. What is the median salary for genetic counselors? What source did you use to answer this question?


Finally a totally voluntary assignment (no points): Tells us (or show us) what you are doing these days to relax and have fun. Nothing offensive to others, please! (This is a classroom. Be professional). Leave (polite) comments in someone else’s posting. I’ll go first!






Order a unique copy of this paper
(550 words)

Approximate price: $22

Basic features
  • Free title page and bibliography
  • Unlimited revisions
  • Plagiarism-free guarantee
  • Money-back guarantee
  • 24/7 support
On-demand options
  • Writer’s samples
  • Part-by-part delivery
  • Overnight delivery
  • Copies of used sources
  • Expert Proofreading
Paper format
  • 275 words per page
  • 12 pt Arial/Times New Roman
  • Double line spacing
  • Any citation style (APA, MLA, Chicago/Turabian, Harvard)

Our guarantees

We are committed to making our customer experience enjoyable and that we are keen on creating conditions where our customers feel secured and respected in their interactions with us.
With our qualified expert team who are available 24/7, we ensure that all our customer needs and concerns are met..

Money Payback-back guarantee

Our refund policy allows you to get your money back when you are eligible for a refund. In such a case, we guarantee that you will be paid back to your credit card. Another alternative we offer you is saving this money with us as a credit. Instead of processing the money back, keeping it with us would be an easier way to pay for next the orders you place

Read more

Zero-plagiarism guarantee

All orders you place on our website are written from scratch. Our expert team ensures that they exercise professionalism, the laid down guidelines and ethical considerations which only allows crediting or acknowledging any information borrowed from scholarly sources by citing. In cases where plagiarism is confirmed, then the costumier to a full refund or a free paper revision depending on the customer’s request..

Read more

Free-revision policy

Quality is all our company is about and we make sure we hire the most qualified writers with outstanding academic qualifications in every field. To receive free revision the Company requires that the Customer provide the request within fourteen (14) days from the first completion date and within a period of thirty (30) days for dissertations.

Read more

Privacy policy

We understand that students are not allowed to seek help on their projects, papers and assignments from online writing services. We therefore strive to uphold the confidentiality that every student is entitled to. We will not share your personal information elsewhere. You are further guaranteed the full rights of originality and ownership for your paper once its finished.

Read more

Fair-cooperation guarantee

By placing an order with us, you agree to the service we provide. We will endear to do all that it takes to deliver a comprehensive paper as per your requirements. We also count on your cooperation to ensure that we deliver on this mandate.

Read more

Calculate the price of your order

550 words
We'll send you the first draft for approval by September 11, 2018 at 10:52 AM
Total price:
The price is based on these factors:
Academic level
Number of pages