Cell Growth and Division
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Transcript of Cell Growth and Division
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Cell Growth and Division
Amy Yu Biology Honours Specialist AQ
Mentor: Andrew Smereczynsky
http://www.scientistsatwork.be/files/imagecache/foto_group/files/mitosis_cartoon_1.jpg
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“Quiz-Quiz-Swap!”◦ Find a partner, quiz each other, and then SWAP!
Uses◦ As a social, enjoyable activity to review unit
vocabulary◦ To supplement Unit Test Review
Benefits◦ Engages variety of learners (visual, verbal, kinesthetic)◦ Opportunities for student peer feedback ◦ Excellent formative assessment◦ Empowers students to familiarize with accurate terms
Genetics Vocabulary Energizer
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In the Curriculum …
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Grade 10 Science Comparison
10 Applied 10 Academic
Cell cycle, including mitosis
No meiosis covered
Cell cycle
Mitosis in detail
No meiosis covered
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Grade 11 Biology Comparison
11 College 11 University
Differentiating between mitosis & meiosis
Function of meiosisIncluding phases of mitosis
No mitosis
Meiosis in detailIncluding phases, random assortment, crossing over, and non-disjunction
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1. Differentiating between mitosis and meiosis• Sex cells vs. somatic cells vs. body cells
• What are gametes and when are they created?• haploid vs. diploid cells
2. Accurate vocabulary is required for accurate description of processes
• “allele” and “gene” are used interchangably• “homologous pairs” often confused with “sister chromatids” or the
ambiguous term “chromosomes”
3. Resources often do not depict a process, just a static picture of isolated stages /events
Student Challenges
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The classic textbook diagrams
http://www.le.ac.uk/ge/genie/vgec/images/mitosis_meiosis.png
•Does not depict mitosis or meiosis as a dynamic, ongoing process
•Observing dead mitotic cells under a microscope presents similar problems
•Reinforces the misconception that cell division occurs in defined, isolated “stages”
•Does not follow location of genes at different loci
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Studying “living” cells using microscope slides
http://www.biologycorner.com/resources/onionmitosis.jpg
MISS!?!?I can’t see anything!
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Bajema Strategy (Mertens & Walker, 1992)
Improving the Pencil-and-Paper Approach
•Students use coloured pencils and draw 2 pairs of chromosomes•Genes (e.g. A/a or B/b) may be placed on them to trace their movement
(great alternative to the Mendelian punnett square algorithm)• Sequence of events in meiosis is traceable
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Computer AnimationsThe Stages of Mitosis
http://www.youtube.com/watch?v=nPG6480RQo0&feature=related
Meiosis http://www.youtube.com/watch?v=D1_-mQS_FZ0
Computer SimulationsCell Division Gizmo www.explorelearning.com
Variety of manipulatives (pipe cleaners, magnetized chromosomes, etc.)
Alternatives to paper approaches that emphasize the sequential nature of concept
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Poor conceptual organization can impede grasp of future, related concepts
◦ Confusion about mitosis (Grade 10) can discourage students from learning meiosis in Grade 11
◦ Meiosis and genetic inheritance should be taught together to emphasize their relatedness
So What?
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Isolated conceptual relationships are taught ambiguously and without connection to the overall picture ◦ Where do homologous chromosomes come from?
(one comes from maternal gamete, other from paternal gamete)
◦ How are chromatid pairs formed? (DNA replication – Grade 12 concept)
◦ How are chromsomal reduction, allelic segregation, and gene assortment related? (these are often depicted separately with separate diagrams, leading students to believe these are isolated events)
So What?
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4 stations = 4 “Tasks”1 sock = 1 chromosome
black clips = centromeres
As you move through the 4 different “Tasks,” consider:◦ grade/ level where “Task” could be used◦ where student misconceptions could present themselves◦ possible extensions◦ how each “Task” differs from another
Consolidating the process: “Chromosomal Socks” Activity
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Addresses 3 key events of cell division with which students often have errors: chromosome doubling, pairing, and separating
Clarifies confusion between ploidy (# of sets of chromosomes) with chromosome structure, emphasizes the precision of the meiotic process
A kinesthetic, verbal activity which can help both students and teachers identify early misconceptions before they survive and are reinforced
Consolidating the process: “Chromosomal Socks” Activity
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Consolidating the process: “Chromosomal Socks” Activity
Chinnici, Neth, and Somalin. “Using ‘Chromsomal Socks’ To Demonstrate PloidyIn Mitosis and Meiosis.” The American Biology Teacher (2006). 68(2):107.
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Individual or group activities that ask students to compare and contrast , differentiate, or
make associations are excellent ways to catch early misconceptions and build each student’s
confidence with genetics
• Venn diagrams, T-charts• Scrambled terms: place on “mitosis” wall or
“meiosis” wall• Students are given a term/ event and organize
themselves into “Team Mitosis”, “Team Meiosis,” or both
Differentiating between Mitosis & Meiosis: Tools
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Teacher: “Notice how during Metaphase I [in meiosis], the homologous pairs match up at the equator. This differs from metaphase in mitosis, where the
sister chromatids line up at the equator.”Student: (confused) “Aren’t homologous chromosomes and sister chromatids the same thing?”
[After backtracking for the 3rd time this week, this lesson goes over time and/or is unfinished, much to
the teacher’s delight]
the importance of words …
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Foldables
ABC’s Activity: Vocabulary Brainstorm
Quiz-Quiz-Swap
Word Walls
Picture Cards
Mastering the Vocabulary: Tools
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Materials◦ jerseys/ T-shirts of different colours (4 each)◦ stockcards with terms or concepts to be covered
Benefits
◦ low-cost materials◦ engages all of the senses – appeals to auditory, kinesthetic,
interpersonal and visual learners◦ concrete learning of an abstract concept
Extensions or Applications◦ can be extended to demonstrate meiosis, mistakes in
meiosis leading to polyploidy
Role-Playing Mitosis
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Causes of cancer, cancer treatments
Stem cell research
Cloning
Genetic diseases arising from mistakes in meiosis (polyploidy), sex-linked diseases
Fertility and other reproductive issues
Applications and Societal Implications
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graphic organizers, collaborative learning activities, microscope labs
Listen/watch for misconceptions, catch them early!
Bajema strategy pencil-and-paper check
Role Play Summaryto ensure connection between physical activity and mental
images of mitosis
Formative Assessment IdeasLesson Sequence available in Handout
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Possible Criteria to Evaluate Student Understanding of Cell Division• vocabulary
• drawing or interpretation of phases• accurate labeling of structures
• accurate depiction of sequential events
Give students choice, differentiate possible products:• “Mitosis Booklet” or “Meiosis Booklet”
• Comic strip – using Comic Life Technology• TV Script – TV skit
• Animations• Poem or Song
Summative Assessment IdeasLesson Sequence available in Handout
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Hopefully this can be added to your teacher toolbox!
Thank You!
Questions?