biology 12 the cell cycle: a closer look!. funny?
TRANSCRIPT
B I O LO GY 1 2
THE CELL CYCLE: A CLOSER LOOK!
FUNNY?
REVIEW (FROM LAST CLASS):
WHICH STAGE IS LONGEST?
INTERPHASE
• Aka the resting phase (but not really…)• Essentially, the cell is in between divisions and is
carrying out maintenance activities of the cell• Made up of 3 sub-phases:
1. G1 phase
2. S phase3. G2 phase
INTERPHASE: G1 PHASE
• 1st growth phase • Cell mature by making more cytoplasm &
organelles• Cell carries on its normal metabolic activities,
such as synthesising proteins
Two identical copies of DNA
Original DNA
INTERPHASE: S PHASE
• Synthesis stage• DNA is copied or replicated
INTERPHASE: G2 PHASE
• 2nd Growth Stage• Occurs after DNA has been copied• All cell structures needed for division are
completed (e.g. centrioles)• Both organelles & proteins continue to be
synthesized
MITOSIS
• Aka karyokinesis• Division of the nucleus• Only occurs in eukaryotes
• Made up of 4 phases:1. Prophase2. Metaphase3. Anaphase4. Telophase
MITOSIS: PROPHASE
• Early prophase:• Centrioles: make spindle fibres and move towards
opposite plates• Chromosomes shorten and thicken (now visible under a
microscope)
• Late prophase:• Centrioles reach poles• Nuclear membrane (envelope) & nucleolus start to
disappear
MITOSIS: METAPHASE
• Spindle fibres attach to centromeres• Sister chromatids (doubled chromosomes) line up
at equator (middle of cell)• Guided by spindle fibers
MITOSIS: ANAPHASE
• Centromeres divide in two• Spindle fibers contract
and pull sister chromatids towards opposite ends of cell (pole)• Each pole (future
daughter cells) will have an identical set of chromosomes
MITOSIS: TELOPHASE
• Sister chromatids at opposite poles• Spindle disassembles• Nuclear membrane forms
around each set of sister chromatids• Nucleolus reappears• Chromosomes loss their
distinct outlines reappear as chromatin
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IN PICTURES:
•Prophase•Metaphase•Anaphase•Telophase
CYTOKINESIS:
• Means division of the cytoplasm• Division of cell into two, identical halves called
daughter cells• Would this happen the same way in plants and
animal cells? Why or why not?• In plant cells, cell plate forms at the equator to divide cell• In animal cells, cleavage furrow forms to split cell
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CYTOKINESIS
Cleavage furrow in animal cell
Cell plate in animal cell
HELPFUL HINT?
• Interphase• Prophase• Metaphase• Anaphase• Telophase• Cytokinesis
IPMATC
Amimation:
• http://www.youtube.com/watch?v=AhgRhXl7w_g&feature=fvsr
TO DO:
• Mitosis colouring sheet• Labelling sheet• Nelson Bio 11 Book• #1 to 9