Procedures 1 Determine the various characters expressed in your phenotype. A Record whether the student is positive or negative for the following traits. (Note: For blood type record the student’s blood type instead of whether the student possesses the trait.) These results are the phenotypes. Blood type: A B or O (Record blood type.)? · Widow’s peak · ?Free ear lobes? · Tongue rolling? · Hitchhiker’s thumb? · Left thumb dominance? · Little finger bend? · PTC taster · ?Mid-digit hair? · Facial dimples? · Freckles? · Cleft chin B List the possible genotype/s for each trait from Part A. C Select three traits to investigate further. Record whether the parents also possess the traits or not. Then create Punnett squares to see what the possible genotypes and phenotypes would be for the trait in children born to the student’s parents. For example if the student has a widow’s peak it is a dominant trait. The student’s Mom also has a widow’s peak but the student’s Dad does not. Knowing that the absence of a widow’s peak is recessive the student’s Dad’s genotype must be ww. Since a widow’s peak is a dominant trait the student’s Mom’s genotypes could be Ww or WW. Therefore to determine possible presence of a widow’s peak in the children the student will create two Punnett squares – one with a cross of ww x WW and a second with a cross of ww and Ww. Record the results in the form of a ratio or percent chance of the trait being present in children with each cross. D Create a karyotype of an unknown individual’s chromosomes presented by clicking on the activity below. Be sure to record the case number provided as it will be needed later. If the image does not load properly or the chromosomes are difficult to match due to the size please click on the link at the top of the activity and print off the chromosomes. To construct the karyotype observe the chromosomes for similarities and match them by pairs of two. Drag the first two chromosomes that match into the first window. When constructing karyotypes the homologous chromosomes should begin with the largest chromosome pair in the first window. Place subsequent pairs in the windows according to the next largest size. There should be a total of 22 pairs of matching chromosomes; the twenty-third pair of chromosomes determines the sex of the individual. If using printed chromosomes each chromosome should be cut out and then matched with the corresponding chromosome. The chromosome pairs should be taped or glued to a clean sheet of 8 ½ x 11 inch printer paper with pairs arranged from largest to smallest. Once the karyotype is constructed identify the sex of the individual as well as the chromosomal disorder they have. Note: Not all individuals will have a chromosomal disorder. E Create a Punnett square that determines the probability of male offspring having hemophilia when the father has hemophilia (Y Xh) and the mother is a carrier (XH Xh). Record the results. Assessing Your Learning Compose answers to the questions below in Microsoft Word and save the file as a backup copy in the event that a technical problem is encountered while attempting to submit the assignment. Make sure to run a spell check. Copy each answer from Microsoft Word by simultaneously holding down the Ctrl and A keys to select the text and then simultaneously holding down the Ctrl and C keys to copy it. Then click the link on the Lab Preview Page to open up the online submit form for the laboratory. Paste the answer for the first question into the online dialog box by inserting the cursor in the box and simultaneously holding down the Ctrl and V keys. The answer should now appear in the box. Repeat the process for each question. Review all work to make sure that all of the questions have been completely answered and then click on the Submit button at the bottom of the page. LAB 7 1 List whether the student was positive or negative for each characteristic and include whether the characteristic is dominant or recessive. (6 points) a Blood type b Widow’s peak c Free ear lobes d Tongue rolling e Hitchhiker’s thumb f Left thumb dominance g Little finger bend h PTC taster i Mid-digit hair j Facial dimples k Freckles l Cleft chin 2 Can the student tell from the blood type if the student is heterozygous or homozygous? Explain. (5 points) 3 Select a trait of interest. a What is the trait? (1 point) b What is the phenotype for the trait? Is this the dominant or recessive allele for the trait? (2 points) c What are the possible genotypes for the parents? (2 points) d Include the results of one Punnett square showing a possible combination between alleles for the trait from the parents by filling in the genotypes according to the numbers in the square below. 1 2 3 5 6 7 8 4 e Based on the cross what percent of children born to the parents would express the trait? (1 point) 4 Create a Punnett square to determine the possibility of a couple having a color-blind child if the mother has the recessive trait on one X and the father is color-blind. HINT: Use Xb to indicate an X with the color-blindness trait. How many female offspring will be color-blind? How many male offspring? (5 points) 5 What was the group number of the student’s karyotype? What was the result of the student’s karyotype? (Include the sex and the chromosomal disorder if applicable. If there was no chromosomal disorder the student must state that the individual was normal.) (5 points) 6 Give an example of a situation in which it is important to create a karyotype for an individual. Explain. (5 points) 7 Genetically speaking why is it important not to mate with a close relative? Explain. (5 points) 8 Does a karyotype tell all of a person’s genetic characteristics? Explain. (5 points) 9 Why is a photograph of cells in metaphase utilized when constructing a karyotype? (5 points) 10 What does it mean to be a carrier of a genetic defective characteristic? When might it be important to know if one is a carrier? (5 points) 11 From the hemophilia procedure: (4 points) a What were the possible genotypes of the offspring? b What is the probability of males having hemophilia? c How many females would have hemophilia? d How many carriers would there be? 12 Explain why more males tend to suffer from X-linked disorders than females. (5 points) 13 The student has a friend that knows the student is taking biology and she is confused about her blood type. Her blood type is O but her dad is A and her mother is B. She asks the student if it is possible for her parents to have a child that is O. Explain the answer to her. (5 points) 14 In a flower garden the gardener has purple and white pansies. He notices that a new pansy has sprouted. When it finally flowers the pansy is lavender. Explain how this happened. (5 points) 15 With a botanist friend’s help the gardener decides to cross the lavender pansy with the white pansy. Will this result in any purple pansies? Explain. (5 points) 16 (Application) How might the information gained from this lab pertaining to human genetics be useful to a student enrolled in a healthcare related profession? (20 points)
