Mitosis & Mutations
How Our Cells Divide
September 15, 2012
Mitosis
O What is it and where
does it occur?
O Why do I need to learn
about it?
O How does it work?
Parts of a cell
Eukaryotic cell cycle
O A cell is “born”
O Nucleus divides/DNA replicates (still diploid)
O Cell grows
O Cell prepares to divide
O Cytokinesis occurs
O Cells separate= mitosis led to 2 IDENTICAL cells!
Overview on cell cycle
Stage 1: Interphase
O Period when the cell is not dividing
O Doing its daily metabolic business
O Chromosomes not clear
O Cell may contain a pair of centrioles
Interphase: s phase
O Period in interphase
O DNA replicates,
chromosomes duplicate
O Chromatid v. Chromosome
Stage 2: Prophase
O Chromatin in the nucleus begins
O
O
O
O
to condense, visible
Centrioles migrate to opposite
ends
Fibers extend from centrioles
Some fibers start to form the
mitotic spindle
No crossing over
Stage 3: Prometaphase
O The nuclear envelope dissolves
O Proteins attach to the
centromeres, creating
kinetochores
O Microtubules attach at
kinetochores and chromosomes
begin moving
Stage 4: Metaphase
O Spindle fibers alight
chromosomes along the
“equator”= metaphase plate
O Helps in organization for next
phase- ensures each side will
receive one copy of each
chromosome
Stage 5: Anaphase
O Paired chromosomes separate at the
kinetochores
O Migrate to opposite ends
Stage 6: Telophase
O Chromatids arrive at opposite
poles of cell
O New nuclear envelope form
around the daughter nuclei
O Chromosomes decondense
and are no longer visible
O Spindle fibers break down
Stage 7: Cytokinesis
O Animal cells: A fiber ring made from the
protein actin begins pinching the cell into 2
daughter cells, each has 1 nucleus
O Plant cells: rigid wall, requires cell plate be
synthesized between the 2 daughter cells
ippmatc
O Interphase, Prophase, Prometaphase,
Metaphase, Anaphase, Telophase,
Cytokinesis
O Is Peter Parker Meeting At The Comic-con?
O Is Pablo Picasso Making A Tinted Collage?
Mutations
O Can occur during the S phase of Interphase
when DNA is being replicated
O Not inherited (body cell, not gametes)
O Carcinogens= chemicals that can cause cancer
O Increase carcinogens= mutations more likely
O More mutations can lead to cancer
O Cancer is caused by uncontrolled growth of cells
Cell immortilization!!
O Henrietta Lacks, HeLa
cells
O Contact inhibition
O Increased telomerase
activity
Major Project
O Small groups
O Assigned a stage or mutations
O Creative video “reenactment”
O Made into class video
O Vote
O Winning class gets free Musical Homework
pass
Creative Examples
O Class Mitosis Dance
O Glow Song
Or use Food!
Quiz examples
Quiz Examples
Questions?
References
O http://www.biology.arizona.edu/cell_bio/t
utorials/cell_cycle/cells3.html
O http://glencoe.mcgrawhill.com/sites/0078802849/student_view0/
unit2/chapter9/section2/selfcheck_quizzes-english.html
O http://www.biosciweb.net/biosex/pdf/Cell
%20Division%20&%20Cancer.bms136.pdf