BIOL 101 Guided Reading Questions GRQs Complete and submit this GRQ as a PDF before lecture and before your online Mastering Assignment L10 GRQs Meiosis Reading Objectives Define and apply the terms somatic cell gamete sister chromatid homologous chromosomes diploid haploid Contrast meiosis from mitosis in the stages and outcomes Explain how meiosis creates such great variation Module 8 11 Chromosomes are matched in homologous pairs 1 In humans we have 46 chromosomes in any somatic body cell Each of these is a pair For example you have two copies of chromosome number 1 You inherited one from the egg cell and one from the sperm cell that combined to make you What do we call these pairs of chromosomes Homologous 2 Why are these pairs not identical Because it takes geners from both parent cells 50 50 Module 8 12 Gametes have a single set of chromosomes 1 Use the following words to describe the life cycle of humans make a concept map or diagram diploid haploid egg sperm meiosis zygote fertilization mitosis adult Diploid a cell containing two homologous sets of chromosomes Haploid cell with a single chromosome set Egg womens sex cell Sperm men sex cell Meiosis sex cells reproduction Zygote first cell formed when a sperm cell fertilizes an egg cell Fertilization sex cells meet Mitosis body cells reproduction Adult parent 2 A diploid organism has 22 chromosomes in its somatic cells How many chromosomes will be in the gametes 23 3 Contrast the term diploid from haploid Diploid a cell containing two homologous sets of chromosomes Haploid cell with a single chromosome set BIOL 101 Guided Reading Questions GRQs Complete and submit this GRQ as a PDF before lecture and before your online Mastering Assignment 4 How many divisions take place in mitosis 1 How many in meiosis 2 5 If a fruit fly cell has 8 chromosomes how many chromosomes will be in the daughter cells after a cell goes through mitosis 8 How many chromosomes are present in daughter cells after meiosis in a fruit fly 4 6 During anaphase I what is being pulled apart Homologous chromosome pairs 7 During anaphase II what is being pulled apart sister chromatids 8 Are the cells produced just after meiosis I considered haploid or diploid and why haploid there is only one set 9 Why is another division needed after meiosis I it is still made up of two sister chromatids Module 8 13 Meiosis reduces the chromosome number from diploid to haploid 1 Feel free to skim the figure here but Figure 8 12B and 8 14 are the level of detail I would like you to focus on 2 Crossing over occurs during prophase I What does this mean exactly nonsister chromatids of each homologous pair of chromosmes exchange segements Module 8 14 Mitosis and meiosis have important similarities and differences 1 Examine figure 8 14 what makes metaphase I different from metaphase of mitosis Mitosis has individual shromosmes line up while meiosis has pairs of homologous chromosomes line up in the middle 2 Why are the chromosomes colored red and blue in this figure What does red or blue represent So they can show how they cross over Module 8 15 Independent orientation of chromosomes in meiosis and random fertilization lead to varied offspring 1 While mitosis produces cells that are identical to the parent meiosis produces gametes that have half the genetic content as the parent cell and produces much variation This variation shuffles up the genetic content so that every gamete produced from a single person is unique As this incredibly unique sperm randomly fertilizes an incredibly unique egg unique offspring That is why you are the only YOU aside from any identical twins in the class So where does the variation come from Independent orientation and crossing over Let s explore the significance of these processes BIOL 101 Guided Reading Questions GRQs Complete and submit this GRQ as a PDF before lecture and before your online Mastering Assignment Describe for yourself or draw based on fig 8 15 why independent orientation of homologs at metaphase I produces variation Each chromosme chooses its own pair Module 8 17 Crossing over further increases genetic variability 1 Explain why crossing over between homologous chromosomes produces variation Because its taking peices from one homologous chromosome and crossing over creating a different one 2 Imagine a chromosome that has alleles R and g on it The homologous chromosome has different versions of these genes and contains the r and G versions What are the possible gamete combinations that can occur Draw it out if it helps R G R g r G r g
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