Biology 120 Structured Study Session Lab Exam 2 Review

Transcription

1 Biology 120 Structured Study Session Lab Exam 2 Review *revised version Student Learning Services and Biology 120 Peer Mentors Friday, March 23 rd, :30 pm Arts 263 Important note: This review was written by your Biology Peer Mentors (not the lab instructors)! It is designed to help you test yourself on topics and concepts covered in lab and should not in any way be considered a preview of the actual exam. You are encouraged to attempt to complete this review without the lab manual, text book, your notes, or the internet. The peer mentors are available while you are working to help you with any questions that cause you difficulties. If you find that the room is too noisy for you to concentrate, Room 212 is a designated Quiet Work Space. Revisions after the lab review session Question 6: should read X-linked allele B rather than X-linked allele b Question 7, parts c-f: Missing information - Mittens is heterozygous Question 22: please note that there are two dark rectangles at the lower left side of the image Structured Study Session information (sessions end the week of April 2-6) Mondays 4:30-5:50pm Murray G3 (Tara) Tuesdays 3:00-4:20pm Arts 210 (Cameron) Wednesdays 12 noon-1:20pm Thorv 159 (Mars) Thursdays 5:30-6:50pm Arts 202 (Justin) SSS webpage: References Buchanan, F. (2018). Inheritance Patterns. Lecture. ANSCI 313. January 3, Schmutz, S. M. (2004, February 13). General Genetics References. Retrieved March 21, 2018, from Schmutz, S. M. (2016, May 7). Genetics of Coat Color and Type in Dogs. Retrieved March 21, 2018, from

2 Spot Test

3 Short Answer 1. Fill in the blanks a. In ferns, meiosis occurs inside the, producing. b. The fern gametophyte can also be called a. c. In animals two haploid cells called combine to form a diploid cell called a in the process known as. d. Crossing over occurs during of meiosis and the region of the chromosomes where this occurs is called the. e. Female mice produce gametes called in their and male mice produce gametes called in their. 2. The Manx cat is a breed of domestic cat that has a shorter than normal tail. The short tail (T) mutation is dominant to normal tail (t), but the short tail mutation is homozygous lethal and usually results in miscarriages. A male Manx cat is bred with one Manx female and one normal female. What are the genotypic and phenotypic ratios of the kittens born for each cat? Show your work.

4 3. Oculocutaneous albinism and α-mannosidosis are both genetic disorders that can affect Angus cows. Both disorders are autosomal recessive and are found on different chromosomes. Oculocutaneous albinism causes the animals affected to have white eyes. Animals affected with α-mannosidosis, caused by the lack of the enzyme α-d-mannosidase in the lysosome, are characterized by their failure to thrive, with death inside the first year (and before they are able to reproduce). Use the letter A for the gene associated with Oculocutaneous albinism and B for the gene associated with α-mannosidosis. Farmer Jim has 1 bull and 48 cows. All of the animals are heterozygous for both traits. a. Draw the Punnett Square to illustrate the cross between the bull and one of the cows. b. What is the expected phenotypic ratio of this cross? c. If the bull sires one calf on each cow, how many calves will be born with white eyes?

5 4. White Heifer Disease is a congenital reproductive abnormality in white female offspring (heifers) in certain breeds of cattle, such as Belgian Blue and Shorthorn. WHD is actually the result of two autosomal genes, H and R- white fur colour is recessive (h), and typically linked with the recessive allele that causes defects in the female reproductive tract (r). a. Draw a Punnett square for a cow heterozygous for both traits being bred to a bull that is also heterozygous for both. The parents of both all have typical WHD linkage- the allele h linked with the allele r. Assume no crossing over occurs. b. What is the genotypic frequency resulting from this cross? c. If the heterozygous bull and the heterozygous cow had only female offspring what proportion would have normal reproductive systems? d. University of Saskatchewan geneticists discovered that the genes for coat colour and reproductive system are 1 map unit apart. If 200 heterozygous cows were bred to a homozygous recessive bull, how many calves would have white coats and normal reproductive systems? Assume that all offspring are female, and that each cow has only one calf. e. Draw a chromosome diagram for a cell of the bull from d. in Anaphase I of Meiosis. Assume that no crossing over occurs. Label the alleles on all chromatids.

6 5. Another genetic disease affecting Belgian Blue cattle is double muscling. It is caused by a single gene mutation that reduces or eliminates the activity of the myostatin protein. Use D to represent the allele responsible for the normal phenotype and d to represent the allele leading to the double muscling phenotype. A Belgian Blue breeder kept track of her herd using the pedigree chart below. a. Based on the pedigree, is this likely a sex-linked trait? b. Give the genotypes for each of the following individuals: c. What proportion of the offspring in the third generation are heterozygous? 6. In domestic cats, an orange coat colour is caused by an X-linked allele b B and is dominant to a black coat colour. a. An orange female cat had a litter of 9 kittens: 5 orange females, 2 orange males, and 2 black males. What is the genotype of the mother cat? b. You have two male cats that could have sired this litter of kittens. One is orange and one is black. Is it possible to tell which one of these cats is the father based on the phenotypes of the kittens? If so, which was most likely the sire?

7 7. Domestic cats can have unique phenotypes. One such phenotype is heterochromia; that is when the cat s eyes are two different colours. Another unique phenotype that can occur in cats is called polydactyly; that means that the cat has an extra digit on each of its paws. Use the letter H for the gene associated with heterochromia and D for the gene associated with polydactyly. A female cat that was homozygous normal for both traits had a litter of kittens sired by a male cat that was homozygous for both polydactyly and heterochromia. All of the cats in the litter had eyes that were different colours and extra digits. a. Is the gene for polydactyly X-linked or autosomal? Is the gene for heterochromia X-linked or autosomal? b. Is the allele for polydactyly dominant or recessive? Is the allele for heterochromia dominant or recessive? Mittens was a polydactyl cat with heterochromia, heterozygous for both traits. Her mother had the normal number of digits, but eyes of different colours (and was true breeding for both). Mittens had kittens with a cat named Boots, who had the normal number of digits and eyes of the same colour. c. What is Mittens genotype? d. What is the genotype of Mittens mother? e. What is Boots genotype? f. If the genes for polydactyly and heterochromia are 18 map units apart, what is the expected phenotypic ratio of their offspring? g. Draw a chromosome diagram for Mittens cell in Telophase II of Meiosis. Assume no crossing over has occurred. Label the alleles on all chromatids.

8 8. Circle the material best suited for DNA extraction: Urine Hair Red Blood Cells Why? 9. What role do the solutions below have in DNA extraction as performed in Lab 7? a. Sports drink: b. Detergent: c. 70% ethanol: 10. What does PCR stand for? 11. What are the four ingredients required for PCR? i. ii. iii. iv. 12. Describe the three steps in the PCR cycle: a. b. c.

9 13. What does Taq polymerase do? 14. What is a thermal cycler? 15. EcoRI is a type of and recognizes/cuts the DNA sequence. 16. What is gel electrophoresis? 17. Gels are made of, which is a polysaccharide derived from. 18. DNA is charged, because of its backbone, which means that DNA will migrate towards the electrode. 19. fragments travel farther than fragments. 20. Which stain can be visualized under white light?. Which stain can only be visualized under UV light? 21. What is the purpose of the ladder in gel electrophoresis?

10 22. Use the following gel to put the sample numbers in order from smallest fragment to largest. Ladder Labrador Retrievers come in three major coat colours: black, chocolate (brown), and yellow. These three coat colours are determined by mutations in the MC1R (melanocortin receptor 1) and the TYRP1 (tyrosinase related protein 1) genes. The TYRP1 gene has two different alleles: B gives the black phenotype, and b gives the brown phenotype. MC1R also has two different alleles: E allows either the black or the brown phenotype to be shown, while e only allows the yellow phenotype to be shown. In order to determine the coat colour for a dog, two different gels need to be run, one for each the MC1R and TYRP1 genes. The MC1R gel uses DNA cut with a restriction enzyme that will cut the e allele (resulting in two smaller pieces of DNA), but not the E allele. The TYRP1 gel uses a restriction enzyme that will cut the the b allele but not the B allele. The gels below show the results of DNA from four different dogs. Assuming that all the dogs are homozygous for both traits, determine the coat colour of each. MC1R TYRP1 Ladder Ladder Dog 1: Dog 2: Dog 3: Dog 4 Bonus: How many pieces of DNA would a dog that was heterozygous for MC1R have in their MC1R gel?