BS 162 Common Homework for Genetics F23

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Name: Lohann Curtil Directions: You should work on this genetics homework over the next few weeks as you go through the genetics section of your BS 162. This assignment is meant for you to complete and use as a reference in this class and future genetics classes to help you understand the fundamental concepts in genetics. Feel free to make any notes to yourself in the margins so when you look back at this document, you will remember your thinking at the time. Once you have completed this document, you should compare it to the rubric and then you should scan it and keep it as a digital copy in your D2L Portfolio. The word bank at the end of the document is for your reference. You will receive further instruction on how to use your D2L Portfolio from your instruction team. Due by 11:59 p.m. on Monday, October 9 BS 162 Common Homework for Genetics Section Petunias are a common flower around the world because of their bright colors and long blooming cycles, but Petunias are native to South America. Petunias are diploid with 14 chromosomes. For a particular species of petunias, the different color plants can all be interbred in greenhouses, however, these different color plants typically do not breed in their natural environment because different organisms are responsible for pollinating each color. Flowers can attract different pollinators based on the color of the flower in the daytime and the ability to absorb UV light which is visible at night. Bees and birds are attracted by bright colors like reds and purples while moths are attracted by strong UV absorbance which is usually found in white flowers. Remember that pollination is essential to flowers for reproduction. Without their pollinators helping, the flowers would not be able to reproduce naturally. **A majority of this case study is taken from--Hester Sheehan et al. 2016. MYB-FL controls gain and loss of floral UV absorbance, a key trait affecting pollinator preference and reproductive isolation. Nature Genetics 48, 159-166. Table 1. Flower color and Primary Pollinator for Three Colors of Petunias Flower Color in visible light Ability to absorb UV light Primary Pollinator Purple Minimal UV light absorption Bees White High UV light absorption Moths Red Minimal UV light absorptions Hummingbirds Researchers are interested in whether the differences in flower color and the ability to absorb UV light are controlled primarily by genetic factors OR in response to environmental factors. One group of researchers, led by Foster, proposed that the plant can change the color of its flowers and its ability to absorb UV light based on the density and species of pollinators in the area. Another group of researchers, led by Sheehan, believes that there is a single gene that is primarily responsible for flower color and UV absorption and the plants can not change their

flower colors during their lifetime regardless of density and species of pollinators in the environment. Q1a. [3 pts] In 2-3 sentences briefly explain how you would design an experiment that would test Foster’s proposal, that plants can change their flower color based on pollinator density and species composition to increase pollination. An experiment that could be conducted is one where we take 3 different colored plants into controlled environments. Within these environments we change the number of pollinators there. As a control we can have zero pollinators then for the next test we have a large density of pollinators and one with a lower density. And we do this for each plant. Q1b. [2 pts] What is the null hypothesis for the experiment to test Foster’s idea? There is not enough evidence to say there is a significant relationship between pollinators density and the increase of pollination. Q1c. [2 pts] What is an alternative hypothesis for the experiment to test Foster’s idea? There is enough evidence to show that there is a relationship between pollinator density and increase in pollination. Q1d. [4 pts] Based on your experiment in 1a, draw a figure that would show data that does NOT support Foster’s ideas that plant color would change based on pollinator density and composition. Make sure you label the axes and the scale marks/tick marks.

Q1e. Below your figure, write a figure legend that includes complete sentences explaining what the figure is representing. Figure1: The figure above has an x axis of Density and a Y axis of Number of plants. The Y axis has 3 points at 500, 1000, and 1500. Each bar in the graph represents bees, moths, and hummingbirds.

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For the upcoming spring, Patriotic Plant Company (PPC) wants to create a plant that produces flowers that are red, white and blue and also are extra large. The researchers at PPC have found a species of Petunias with a single gene for petal color. The petal color gene is located on chromosome 6. The allele, R, produces red flowers in the homozygous form and the allele, W, produces white flowers in the homozygous form. In addition, the gene for petal color shows co-dominance in the heterozygous form. The researchers have also located a gene in tropical frogs, called FRG, that produces a blue protein called Ranasmurfin (Cooper and Kennedy Biophys. Chem. 2010) in either the heterozygous and homozygous dominant form. The researchers have successfully inserted the FRG gene on chromosome 7 of this species of petunias. Finally, on chromosome 8 is a gene that controls size of the flowers in the plants. The B1 allele produces extra large flowers and is dominant to both the B2 (medium flowers) and B3 (small flowers) alleles. B2 is dominant to B3. Fill in the table below to help you keep track of the genes. We have filled in the information for chromosome 6. Chromosome Number Location Alleles Genotypes Phenotype 6 R or W RR, RW, WW Red, Red and White, White 7 F or f. FF, Ff, ff Blue, Blue, Not blue 8 B1,B2, B3. B1B1, B2B2, Extra large, medium, small B3B3,B1B2, B1B3, B2B3 In the main office at PPC, there is a petunia plant that has all medium flowers (let’s assume it is homozygous for the flower size gene). The flowers have both red and white blotches on them. It does not have any of the blue color because it has the genotype “ff” for the FRG gene. It is receiving plenty of nutrients and sunlight in the office and is growing quickly. Imagine you are drawing a cell is the leaf of your plant. In the drawings, label all alleles present in each drawing. Label sister chromatids and homologous pairs at least once for Q3 a-c. Q2. If we are focusing on a cell in the leaf whose primary function is growth, what process would we be modeling? Name that process and explain its primary purpose [2 pts] The process we are modeling is mitosis. We are modeling it because its purpose is to reproduce over and over again. It produces genetically identical daughter cells.

Q3a. Draw a nucleus of this plant in phase G1 of the cell cycle. Show chromosomes 6, 7, and 8. For your model, answering the following: Number of cells= 1 Is the DNA replicated or unreplicated? unreplicated Is the cell diploid or haploid? Diploid What is the “n” for this particular model? 2n=6 Q3b. Draw a nucleus of this plant in metaphase. Show chromosomes 6, 7, and 8. Reminder: Have you lined up your chromosomes properly so that when the cell divides you will end up with the correct products? For your model, answering the following: R

Number of cells= 1 Is the DNA replicated or unreplicated? replicated Is the cell diploid or haploid? diploid

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What is the “n” for this particular model? 2n=6 Q3c. Draw the product(s) of this process. Number of cells= 2 For you model answer the following questions Is the DNA replicated or unreplicated? unreplicated Is the cell diploid or haploid? diploid What is the “n” for this particular model? 2n=6 Q3d. When we label a homologous pair, does that genetic information come from one of both parents? How does having a homologous pair present in a cell relate to whether the cell is haploid or diploid? The genetic information comes from both the parents. Having homologous chromosomes shows that we have diploid cells because haploid cells contain only half of the necessary amount of chromosomes. Q4. After more research, the team sequences the petal gene to determine the cause of the red versus the white flowers. The top line shows the DNA sequence and the bottom line shows the amino acid that each set of three amino acids codes for. The top two lines are for the R allele and the bottom two lines are for the W allele.

Q4. In the box below, draw the nucleotide base model in the replicated chromosome form for an individual that is heterozygous, RW, for the petal gene. Use only the first 9 nucleotide bases from above (start from the left CCC… ). Red: CCCAAGTCC GGGTTCAGG White: CCCAAGTCT GGGTTCAGA Q5. Based on what you know of the processes from nucleotide sequence to final protein phenotype and function, why is the color of the flowers different for the RR and WW genotypes? They are different because of the function of proteins and the displayed phenotypes are are reliant on the structure of the proteins. Because of the mutation for white pedals instead of red that means that both have a different amino acid sequence and premature stop sequence. The protein will be different.

Q6. The researchers are ready to fertilize an egg from a Ff RW B2B2 plant with pollen from a FF RW B1B3 plant. In the circles below, draw chromosomes showing the homologous pairs for chromosomes 6, 7, and 8 for the flower with the genotype Ff RW B2B2 during metaphase of Meiosis I. Represent the two possible alignments of the chromosomes, due to independent assortment in A) and B). Clearly label all alleles for all genes. Also, label the sister chromatids and homologous chromosomes in at least 1 instance in your drawings if they are present. B) Number of cells=1 For your model A) answer the following questions Is the DNA replicated or unreplicated? replicated Is the cell diploid or haploid? diploid What is the “n” for this particular model? 2n=6 A)

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For your model B) circle the chromosomes 7. Your lab notebook tells you that the maternal lineage of this individual plant has never had blue pigment in the flowers. Now, p ut an “M” by the chromosome 7 that came from the maternal line and a “P” by the chromosome that came from the paternal line. C). How are the 2 sister chromatids similar and/or different in the 7M chromosome? Sister chromatids have to be the same D). How are the 2 homologous chromosomes 7 (7M and 7P) similar and/or different? Sister chromatids have to be the same but homologous pairs can have different alleles for the same gene. Q7. Now draw the chromosomes during metaphase II of meiosis for ONLY the alignment you drew in Q6 A) above . Clearly label all alleles for all genes. Also, label the sister chromatids and homologous chromosomes in at least 1 instance in your drawings, if they are present.

Number of cells= 1 For your model, answer the following questions Is the DNA replicated or unreplicated? replicated Is the cell diploid or haploid? haploid What is the “n” for this particular model? N=3 C) D)

Q9. In the space below, draw all the products of meiosis in the gametes (eggs) for this flower in alignment A).

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Number of cells= 4 For your model, answer the following questions Is the DNA replicated or unreplicated? unreplicated Is the cell diploid or haploid? haploid What is the “n” for this particular model? N=3 Q10 What are the possible genotypes of gametes resulting from Alignment A? B2,R,F,B2,W,f What are the possible genotypes of gametes resulting from Alignment B? B2,W,F,B2,R,f Q11a. Complete a Punnett square of the cross between the Ff RW B2B2 flower with FF RW B1B3 flowers. FRB2 FWB2 fRB2 fWB2 FRB1 FF RR B1B2 FF RW B1B2 Ff RR B1B2 Ff RW B1B2 FWB1 FF RW B1B2 FF WW B1B2 Ff RW B1B2 Ff WW B1B2 FRB3 FF RR B2B3 FF RW B2B3 Ff RR B2B3 Ff RW B2B3 FWB3 FF RW B2B3 FF WW B2B3 Ff RW B2B3 Ff WW B2B3 Q11b. What is the expected ratio of plants that make extra-large flowers that have red, white and blue? [2 pts] The expected ratio for all the traits is 1:4 Q12. What could you do in future crosses to increase the ratio of plants that make extra-large flowers that have red, white, and blue? Cross 2 parent plants that are homozygous for the blue and B1 gene, and heterozygous for the R/W allele. Q13. After you breed your plants about 3 generations, you find that one of your plants is not making any flowers at all. You are curious, so you genotype this plant and find out that it is Ff RRW B3B3. How could this genotype have resulted? Explain in 1-2 sentences or draw a model.

This could have happened in plants that had an extra chromosome with the R allele on it. The adaptation was negative for passing on traits but positive for the species where bad/messed up plants will not reproduce. Word Bank for Genetics These are words that you should be familiar with to understand genetics for this class. You should be able to define them, explain why they are important to genetics, and, in some cases, draw a model to illustrate them. Chromosome Nucleotide base Gene Allele Locus Puffy stick model Nucleotide base model Genotype Phenotype Heterozygous Homozygous Dominant Recessive Mutation Co-Dominant Incomplete Dominant Mitosis Unreplicated Chromosome Replicated Chromosome DNA replication Sister Chromatid Homologous Pairs Centromere Amino Acid Protein Haploid Diploid n and 2n Meiosis Cell Cycle G1 Cell Cycle S Cell Cycle G2

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Transcription Translation Independent Assortment Wild type

BS 162 Common Homework for Genetics F23

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