Lab #3 - BIOL 1001 Winter 2021 - Sickle-Cell Alleles PDF

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Download Lab #3 - BIOL 1001 Winter 2021 - Sickle-Cell Alleles PDF

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BIOL 1001 – Lab 3 – Winter 2021 SimUText Exercise: Sickle-Cell Alleles What you need to complete, deadlines and recommended timeline: 1. If you did not complete lab 2, follow the instructions in the lab 2 handout for setting up your Simbio account and downloading the SimUText application for this course. If you already registered your SimBio account and downloaded the SimUText for lab 2, you do not need to perform these steps again; you will use the same login credentials to access this exercise. 2. If you have not yet done so, read Ch. 23: Evolutionary Processes in the custom text (Ch. 26 in the jellyfish text; Ch. 3 in the forest text) as well as the information provided in this document. 3. Complete the lab 3 pre-lab quiz on the lab eClass site, worth 10% of your lab 3 mark. o Recommend completion by Friday Feb 12 o Deadline for completion (quiz closes) Friday Feb 26, 11:59 p.m. 4. Open the SimUText application you downloaded for lab 2 and complete the Sickle-Cell Alleles exercise (5 sections, including graded questions). If for any reason you need to download the SimUText again, you can do so by logging in to the student portal at https://www.simutextca2.com/student/ . Do NOT purchase another SimUText license from SimBio. o Remember to set the location to “Canada” on the upper left corner of the SimUText login page. It is recommended that you maintain an internet connection while working through the exercise. o The lab 3 SimUText exercise will become available on Monday Feb 8 o Recommend completion by Friday Feb 26 o Deadline for completion: Monday March 1, 11:59 p.m.

Introduction When individuals with specific genetically-influenced traits are being selected against (i.e., they die or do not reproduce because they are not adapted to current environmental conditions), the amount of allelic variation – i.e. the number of different alleles – in the population should decrease. While this increases the frequency of alleles that allow for increased survival/reproduction under current conditions, it ultimately results in reduced genetic variation within the population. Population size can also affect the amount of genetic variation in a population. In smaller populations, there is an increased likelihood that chance events will result in one or more alleles not being passed on to the next generation. Note the word ‘chance’. Even when an allele (and its associated trait) does not confer any selective advantage or disadvantage on the individual that has it – i.e. the allele is “neutral” with respect to fitness – the frequency of that allele may still be affected by chance events. In larger populations, however, the chance that an individual doesn’t pass along a specific allele can be balanced by the chance that another individual bearing the same allele does pass it on to the next generation. This tends to stabilize the frequency of neutral alleles. The Hardy-Weinberg Principle states that genetic equilibrium (a.k.a. Hardy-Weinberg equilibrium) – the maintenance of constant allele frequencies at a particular locus – occurs when 5 criteria are met. These criteria are: 1. 2. 3. 4. 5.

No natural selection (i.e. every individual has an equal chance of reproducing, regardless of genotype) The population is very large (i.e. no genetic drift). The population is isolated from other populations (no gene flow, i.e. no immigration or emigration). Mating occurs at random No mutations 1

These criteria describe the conditions under which a population is not evolving. Thus, if a population does not adhere to these criteria, we should see that it is not in genetic equilibrium. The absence of genetic equilibrium provides genetic evidence that the population in question is, in fact, evolving. Researchers can then investigate what mechanisms underlie the evolution of the population. You will be studying these concepts in relation to the inherited condition called sickle cell anemia. In sickle cell anemia, a mutated form of hemoglobin distorts the red blood cells such that they have a crescent shape. As a result, there are not enough healthy red bloods cells to carry adequate amounts of oxygen throughout the body.

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Grading • • •

Pre-lab Quiz (completed on Lab eClass site) SimUText questions, sections 1-4 (marked for completion) SimUText graded questions in section 5

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10 marks 49 marks 10 marks

10% of lab 3 grade 35% 55%...