Practice set 9 lecs 14-21

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Binghamton University *

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501

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Biology

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Jan 9, 2024

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Practice set 9: Covers lectures 14-21 Complete each set of questions as we advance through the course material. Every question in this exam is connected! Chevonne and Darrel have a baby boy named Ben that quickly begins to develop recurrent bacterial respiratory infections. After genetic testing they find out that Ben has common variable immune deficiency (CVIDS). Common variable immune deficiency (CVIDS) is an autosomal recessive genetic illness. Individuals with the disease have two copies of the mutated /rrba allele, located on chromosome 4. Affected individuals do not produce enough antibodies and thus suffer from recurrent bacterial and viral infections. Further genetic testing reveals that: Both Darrel and Chevonne each have one copy of the mutated recessive /rba allele and one normal copy of LRBA. located on chromosome 4. Darrel has one copy of the mutated recessive ¢f allele, located on chromosome 7. Having two mutated recessive c¢f alleles leads to the development of cystic fibrosis. a different genetic illness. Questions 1-2 cover lectures 17-18. 1. One of the respiratory infections that Ben is continuously suffering from is caused by the Moraxella catarrhalis bacteria. Moraxella catarrhalis has a normally operating lac operon system. When there 1s a high concentration of lactose and a low concentration of glucose in the environment, which genes in the lac operon are expressed? a) lacl, lacZ, lacY b) lacl c) lacZ. lacY In addition, when there is a high concentration of lactose and a low concentration of glucose in the environment, which molecules are active? a) CAP b) RNA polymerase c) CAP.cAMP d) CAP, cAMP. RNA polymerase Questions 3-8 cover lectures 14-15. 3. How did Darrel’s sex chromosomes line up at the metaphase plate (metaphase I) during meiosis of his sperm?

Sex chromosomes Non-sex chromosome (autosome) showed for reference. Sex chromosomes Non-sex chromosome (autosome) showed for reference. B Sex chromosomes Non-sex chromosome (autosome) showed for reference. D Sex chromosomes Non-sex chromosome (autosome) showed for reference. 4. The genetic testing also revealed that Ben has two X chromosomes and one Y chromosome (XXY) a condition called Klinefelter’s syndrome. The source of Ben’s Klinefelter’s syndrome was most likely an error during meiosis of Chevonne’s egg. What did the resulting cells of meiosis I look like during meiosis of Chavonne’s egg (that eventually developed into Ben)? A reference. ex chromosore gUtosome) showed fo reference. B gUtosome) showed o reference. qUtosome) showed fo) reference. 5. Remember. both Darrel and Chevonne each have one copy of the mutated recessive /rba gene and one normal copy of LRBA. Darrel also finds out that he is heterozygous for the Widow’s Peak gene, with T representing the dominant allele and t representing the recessive allele. He is also

heterozygous for the double-jointed gene, D/d. All three genes are located at varying distances apart on chromosome 4. as shown in the diagram below. Maternal Paternal copy T copy D a A Chromosome 4 (unreplicated) One cross over event occurs during Darrel’s sperm production. Ben inherits Darrel’s paternal copy of chromosome 4. Therefore, Ben’s chromosome 4 is most likely to contain: a) TDlrba b) tdLRBA c) tdlrba d) TDLRBA 6. Ben grows into a toddler and Chevonne and Darrel want to have another child. They decide to undergo medical reproduction assistance to ensure that the new baby will not have Kleinfelter’s syndrome and/or CVIDS8. They also want to prevent the new baby from being a carrier of cystic fibrosis. (Remember that Darrel has one copy of the mutated recessive ¢f gene, located on chromosome 7.) Darrel’s sperm is analyzed before fertilization. Considering the diagram of Darrel’s chromosome 4 and 7 below...If Darrel’s harvested sperm contains both the /rba allele and the cf allele, which of the following is true regarding how independent assortment occurred during meiosis? (Consider only independent assortment and not crossing over.) Paternal Maternal Paternal copy copy copy BA Chromosome 4 Chromosome 7 (unreplicated) (unreplicated) a) Parental copies of chromosome 4 lined up on the same side of the metaphase plate as chromosome 7. b) Parental copies of chromosome 4 lined up on the opposite side of the metaphase plate as chromosome 7. 7. The harvested sperm described above is discarded and doctors instead use a sperm that contains the following genotype: LRBA CF. Chevonne’s eggs are not analyzed but instead chosen randomly for fertilization (mimicking the typical process of reproduction). In a punnet square of

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