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Unit 8:
Cell Cycle
& Mitosis
• Cells make more cells by growing and
dividing millions of times a day!!
Two types of cell
reproduction:
• Asexual
• Sexual
Two types of cell
division:
• Mitosis
• Meiosis
Asexual:
• One parent
• Offspring are
clones!!
Sexual:
• Two parents
• Offspring
resemble both
parents!
1.
2.
3.
Body Cells
Before a cell can divide it needs
instructions!!!
• CELL DIVISION OCCURS IN A SERIES OF
STAGES, OR PHASES:
Mitosis
•
•
•
•
•
• Cell grows!!!
• Copies genetic material (DNA) and other
cell organelles
• 1st Growth Stage
• Cells make cytoplasm and organelles
• Cells perform normal duties
• Cells grow RAPIDLY
• Most remain here most of their life.
• DNA is copied or replicated.
• At the end: each chromosome
consists of 2 chromatids attached at
the centromere.
• 2nd Growth Stage
• Cell division structures are made
•
–
• Organelles & proteins are
synthesized
• PREP for nucleus to divide
• Genetic material condenses (shrinks!) to
form chromosomes
• Nuclear membrane dissolves
• Centrioles move to opposite poles
• Spindle fibers form
• Chromosomes line up in the middle of cell
• Spindle fibers are attached!!
• Chromosomes are pulled apart and
chromatids move to opposite ends of the
cell by the spindle fibers.
• Chromatids relax
• Nuclear membranes form around
chromatids
• Spindle fibers fall apart
• “Division of Cytoplasm”
•
forms in animal cells –
pinching inwards by tiny filaments.
•
forms in plants cells – forms inbetween the two nuclei
• Two daughter cells that are identical to the
original cell.
Video
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