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Unit 1: Mitosis & Meiosis
Mr. Nagel Meade High School
Consider
• The DNA in one of your cells is approximately 2 meters long.
• How would you fit all of that into a cell the size of a pin point?
Chromosome Review • Let’s review how DNA is packed for ‘moving’
in your cells… – http://library.thinkquest.org/C004535/chromosom
es.html • How many chromosomes does a typical
human cell have? • What is a centromere? • What is a telomere? How can it contribute to
a cell’s death?
What is a Chromosome?
• How is DNA packaged in an organism?
• Animation: Packing DNA
Anatomy of Chromosomes
• Label: – Centromeres – Sister Chromatids – Homologous Chromosomes
Chromosome Numbers Common Name
Diploid Chromosome
Number Buffalo 60 Cat 38 Cow 60 Dog 78 Donkey 62 Fruit Fly 8 Goat 60 Horse 64 Human 46 Ophioglossum reticulatum (Fern) 1200+ Pig 38 Sheep 54 Turkey 82 Wolverine 42 Yeast 32
Gizmo Sign-Ups
• A2 – WZL3RQR4UH
• A3 – C5GFQMJJMN
• B1 – FSFMCQM4VA
• A3 – C5GFQMJJMN
Time to get Creative!
• Go to: http://www.cellsalive.com/mitosis.htm
• Watch the animation. • Create a story book from two sheets of
paper divided into 4 quarters. – Title, Interphase, Prophase, Metaphase, Anaphase,
Telophase, Cytokinesis, Summary
• Title, draw, and note major events for each!
• Perfect reproduction (two identical nuclei)
• Growth, embryonic development, tissue repair, asexual reproduction
• P.M.A.T.
Mitosis
Name That Phase…
Last Thoughts…
• In the human body, the rate of mitosis is believed to be 25 million cells produced every second!
• That comes out to 2 trillion cells per day!
• Cells that divide rapidly – Skin, Epithelial,
Bone Marrow • Cells that must be
stimulated to divide – Liver
• Cells that do not divide – Nerve, Muscle
Cell Cycle Project
• How long does a typical cell spend in each phase of Mitosis/Cell Cycle?
• Let’s consider an onion root tip cell… – http://www.biology.arizona.edu/cell_bio/activiti
es/cell_cycle/cell_cycle.html
Cell Cycle Project
• How long does a typical cell spend in each phase of Mitosis/Cell Cycle?
• Let’s consider an onion root tip cell… – The average cycle duration is 24 hours.
Interphase Prophase Metaphase Anaphase Telophase TOTAL
Quantity 36
Percent 100%
Time 24 hrs
Cell Cycle Project
• How long does a typical cell spend in each phase of Mitosis/Cell Cycle?
• Let’s consider an onion root tip cell… – The average cycle duration is 24 hours.
Interphase Prophase Metaphase Anaphase Telophase TOTAL
Quantity 20 10 3 2 1 36
Percent 55.6 27.8 8.3 5.6 2.8 100%
Time 13.3 24 hrs
Consider…
• How does your skin know to grow cells when you get cut, but does not grow when you are undamaged?
• Do your cells split on a regular basis? How often? What would be the purpose?
• Could you define the ‘events’ in the life of a cell?
Cell Cycle • All cells undergo the cycle! • Interphase
– G1, S, and G2 • G = Gap • S = Synthesis
– Mass production! • Cancer cells
– What do you think goes wrong?
• Animation! – http://cellsalive.com/cell_cycle.htm
Mitosis vs. Meiosis
• Compare Mitosis – http://www.johnkyrk.com/mitosis.html
• To Meiosis – http://www.johnkyrk.com/meiosis.html
• NOVA side by side animation – http://www.pbs.org/wgbh/nova/baby/divi_flash.html
• Extra Help – http://www.sumanasinc.com/webcontent/animations/content/meiosis.html
Meiosis
• Sex cells – How are they made?
• Like Mitosis, but… – Similarities? – Differences?
• Crossing Over – “Shuffling the Deck”
Models With Plates
• Using the strings and plates model: – A cell in Mitosis (metaphase) – A cell in Meiosis I (Metaphase I) – notice the
difference! – Two cells formed from one (Telopase I) – Two cells in Meiosis II (Metaphase II) – it’s
just like Mitosis! – Four cells created (Telophase II)
• How many chromosomes did we start/end with?!
Vocabulary is Key!
• Somatic Cell • Gamete • Zygote • Haploid • Diploid • Homologous Chromosomes • Sister Chromatids • Autosomal Chromosome • *Crossing Over
