Cell Growth and Division

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

“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

In the Curriculum …

Grade 10 Science Comparison

10 Applied 10 Academic

Cell cycle, including mitosis

No meiosis covered

Cell cycle

Mitosis in detail

No meiosis covered

Grade 11 Biology Comparison11 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

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

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

Studying “living” cells using microscope slides

http://www.biologycorner.com/resources/onionmitosis.jpg

MISS!?!?I can’t see anything!

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

Computer AnimationsThe Stages of Mitosis

http://www.youtube.com/watch?v=nPG6480RQo0&feature=relatedMeiosis

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

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?

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?

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

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

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.

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

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 …

Foldables

ABC’s Activity: Vocabulary Brainstorm

Quiz-Quiz-Swap

Word Walls

Picture Cards

Mastering the Vocabulary: Tools

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

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

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

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

Hopefully this can be added to your teacher toolbox!

Thank You!

Questions?