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The Liggins Education Network for Science LENScience Senior Biology Seminar Series Human Aneuploidy and Related Biotechnologies Questions and Discussion Pre‐seminar School Discussion This seminar focuses on the role of mutations in the inheritance of genetic conditions, and the biotechnologies that can be used to screen and diagnose for these conditions before and during pregnancy. While the focus is on aneuploidy, it will also look at heritable gene mutations. Your understanding from Year 11 and 12 of concepts of cell division, gene expression and mutations will provide you with a starting point. The seminar will link to concepts in the Year 13 Biology programme and develop your understanding of how knowledge of these concepts can be applied in human situations. A list of the Year 13 concepts linked to the seminar can be found on page 4 of this handout. Don’t worry if you have not covered these in class yet. It is recommended that students review this seminar again later in the year once you have completed molecular genetics and biotechnology topics. A Review of Cell Basics Use your knowledge of Y12 Biology and the information in the seminar paper to discuss the following questions. se
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It is expected that you did complete the pre‐seminar questions for seminar 1. If you have not, please review questions 1, and questions 4‐8 from page 1 of seminar 1. 1. The diagram on the right is a human karyotype, containing 22 pairs of homologous chromosomes and the sex chromosomes. a. Is this a male or a female karyotype? b. Explain what homologous chromosomes are and what information they contain. c. Define the term chromatin d. Describe the structure of a chromosome and explain the difference between chromatids and chromosomes. Homologous Pair of Chromosomes 2. Explain the difference between a gene and a chromosome mutation. 3. Cystic Fibrosis and Huntington’s Disease are examples of inherited conditions caused by gene mutations. Cystic Fibrosis has an autosomal recessive inheritance pattern while Huntington’s Disease has an autosomal dominant inheritance pattern. Describe the difference between these inheritance patterns and explain how these differences impact on the likelihood of inheritance of the disease by the child of a carrier parent. The Liggins Education Network for Science Bringing Schools and Scientists Together 1 4. Define the term aneuploidy and explain the difference between monosomy and trisomy. 5. The diagram on the right shows the process of meiosis. Aneuploidy can be caused by non‐disjunction during meiosis, leading to the formation of gametes that are (n+1) or (n‐1). Explain how this occurs. Reproductive Technologies 6. What is the difference between pre‐natal screening and pre‐natal diagnosis? 7. Pre‐natal diagnosis of chromosomal abnormalities uses karyotyping. In pre‐implantation genetic diagnosis karyotype testing is not an option because only one or two cells are collected and the chance of the chromosomes being visible is very slight. At what stage in the cell cycle are the chromosomes visible? Vocabulary Gamete Oocyte Spermatozoa Semen Zygote Blastocyst Embryo Fetus Placenta Chromosome Chromatid Chromatin Autosome Sex Chromosome Karyotype Homologous Gene Bio 3.2 AS 90714 vs 2 Allele Gene Mutation Chromosome Mutation Autosomal Dominant Autosomal Recessive Mitosis Meiosis Aneuploidy Polyploidy Non‐disjunction Monosomy Trisomy Translocation Pre‐natal / Antenatal Screening Diagnosis Trimester Ultrasound scan Chronic Villus Testing Amniocentesis PGD—Pre‐Implantation Genetic Diagnosis Byopsy In vitro fertilisation Fluorescence in situ hybridisation Comparative Genomic Hybridisation Preimplantation Genetic Haplotyping Restriction Enzymes Ligation Anneal Polymerase Chain Reaction Gel Electrophoresis Saviour Siblings Genetic Counselling Research a Contemporary Biological Issue Aspects of reproductive technologies offer good potential as topics for this achievement standard. When selecting a topic you are looking for an issue which will meet the following criteria:  Is it a contemporary issue ‐ this is defined as one for which people hold different opinions or viewpoints  Can you define the biological concepts and processes relating to the issue?  Can you define the implications of the issue—biological, social, economic or environmental? While the use of reproductive technologies such as IVF are reasonable widely accepted in society, advances in reproductive technologies that have led to the availability of Pre‐implantation Genetic Diagnosis offers good potential as a topic for this achievement standard. Issues around decision relating to when PGD should be used and how it should be made available would offer a good starting point for the standard. A discussion around identifying where this technology is appropriate would be very interesting. The use of PGD to create Saviour Siblings is a particular aspect of the issue that would make an interesting topic for this standard. There are extensive links on the Wiki Site designed to support your research if you choose this as a topic for Bio 3.2. 2 Karyotype—Turner Syndrome (XO) Post Seminar Challenge Questions Part A: Questions relating to understanding of genetics 1. Aneuploidy resulting in the loss of an entire chromosome usually results in a non‐viable embryo. However, if the chromosome concerned is the X‐chromosomes the embryo may live. Explain why the loss of an entire autosome is almost always lethal but the loss of the x‐chromosome may not be lethal. 2. Compare and contrast the three possible mechanisms by which Trisomy 21 can arise. Part B: Questions relating to understanding of contemporary issues Designed to assist you in developing your Bio 3.2 assessment report. 3. Pre‐natal diagnosis occurs during pregnancy. Pre‐implantation diagnosis occurs before a pregnancy is established. a. Create a list of possible ethical issues that arise as a result of the use of pre‐natal diagnosis and pre‐
implantation diagnosis technologies. Consider issues from the perspective of the parents, child, impact on society, Māori viewpoints, culture, religion, the viewpoints of those who are affected or whose families are affected by the condition, science................ b. Identify key factors that would influence the opinions of different groups within society in relation to these ethical issues. Part C: Higher order mixed concept question (Genetics / Biotechnology / Ethics) 4. Cystic fibrosis is an autosomal recessive disorder that is carried by approximately 1 in 25 Caucasian New Zealanders. It is rare in Polynesians, Asians and Africans. Huntington’s disease is autosomal dominant condition and is found in about 1 in 20,000 births in Caucasian peoples and is less common in other ethnicities. Discuss the potential impact of the use of pre‐implantation genetic diagnosis technologies on the future frequency of these disorders. Part D: Changing context—same concepts! In the last seminar, it was explained to you that examiners see that students generally find it difficult to apply concepts that they understand to new contexts or situations that are presented in an exam. During Seminar 1 we looked at the role of biotechnologies in the development of effective treatments for cancer and you attempted the question below. Discuss how the use of named biotechnologies has enabled scientists to develop understanding of cancer at a molecular level and how this understanding can then be used in the development of effective treatments. Many of the same biotechnologies are used in Pre‐implantation Genetic Diagnosis. A good way to identify whether you are learning how to apply knowledge to different situations is to apply the same question to a different context. Here is the same question but this time with the context of PGD. Plan an appropriate answer from the information in the seminar paper. The basic technologies you could use are PCR, Restriction Enzymes, Gel Electrophoresis, Fluorescence. 5. Discuss how the use of named biotechnologies have enabled scientists to develop effective methods of diagnosing genetic abnormalities in embryos and how these technologies have met a human need or demand. POST YOUR IDEAS, QUESTIONS AND SUGGESTED ANSWERS AT http://lens.auckland.ac.nz/index.php/Aneuploidy_and_Related_Biotechnologies_Discussion_2009 3 Level 3 Achievement Standards linking to this seminar: AS 90714 Biology 3.2 Research a contemporary biological issue AS 90715 Biology 3.3 Describe the role of DNA in relation to gene expression AS 90718 Biology 3.6 Describe applications of biotechnological techniques Key Concepts from Level 3 Biology that link to this seminar: Below are selected objectives from the Year 13 biology programme that link to this seminar. THESE ARE NOT A FULL LIST OF THE CONCEPTS IN YOUR COURSE. You may wish to review these concepts before the seminar. Molecular Genetics / Mutations Please remember these are only the objectives linking to this seminar—refer to your unit hand out at school for a full list  Describe the principles of simple dominant / recessive monohybrid and dihybrid inheritance patterns and use these to predict the outcome of simple dominant / recessive monohybrid and dihybrid inheritance problems. 
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Determine the outcome of inheritance crosses involving linked and sex‐linked genes. Describe the structure of a chromosome. Describe the process of mitosis and meiosis. Define the term mutation and identify ways in which mutations may affect an organism Identify the causes of mutations Differentiate between somatic and gametic mutations and identify the potential effect of each of these. Describe the effect of gene mutations; identify types of gene mutations and explain the range of potential consequences of these on the expression of the gene.  Describe the effect of chromosome mutations; identify types of chromosome mutations and the range of potential consequences of these on the expression of the gene.  Describe the process that leads to aneuploidy and polyploidy and explain the range of potential consequences of these types of mutations.  Show understanding of molecular genetics by using the core knowledge to give reasons for events that happen in the cell and linking ideas  Show understanding of the cause and effect of mutations by using the core knowledge to link ideas Biotechnology Please remember these are only the objectives linking to this seminar—refer to your unit hand out at school for a full list  Describe the techniques involved in gene cloning and how gene cloning meets human needs and demands.  Describe the techniques involved in DNA profiling and how DNA profiling meets human needs and demands.  Describe the techniques involved in genome analysis and how genome analysis meets human needs and demands.  Be aware of the differing viewpoints of the use of biotechnological applications.  Show understanding of applications of biotechnological techniques by using core knowledge to link ideas Contemporary Biological Issue  Identify a contemporary issue ‐ defined as one for which people hold different opinions or viewpoints  Define the biological concepts and processes relating to the issue  Define the implications of the issue—biological, social, economic or environmental Copyright © Liggins Education Network for Science, 2009 http://LENS.auckland.ac.nz 4