Cell Division
GOAL: To make cells w/ SAME amount of DNA
46
1. Interphase Cell copies DNA
92
2. Mitosis
46
Divides DNA Equally
46
3. Cytokinesis
46
Cytoplasm divides/Cell splits
46
BIG PICTURE:
Cell Division of Human Cells
Why do cells divide?
To create new life:
zygote divides to become ball of cells
Why do cells divide?
Rarely divides
To replace old cells:
Different cells divided at
different rates
Divides once/day
How fast do
Cells divide?
Never divides
Divides once/year
Rarely divides
Why do cells divide?
To help an organism grow:
adding cells makes organism bigger
Why do cells divide?
To heal from injury:
new cells fill in to help repair
Learning Terms
Thin/Stringy DNA
seen in interphase
Tightly coiled DNA
Seen in mitosis
Exact copies
centromere
Chromatin
Chromosome
Duplicated
Chromosome
Interphase
THINK! – What 2 things happen
during interphase?
Cell grows
Cell copies (doubles) its DNA
Mitosis (4 Phases)
The cell divides the DNA molecules equally
THINK! – A mosquito normally has 6 DNA
molecules. How many molecules will each cell
have after mitosis? 6
THINK! – Humans normally have 46 DNA
molecules. How many molecules will each cell
have after mitosis? 46
Phase 1: Prophase (P= Prepare)
Chromatin coils into chromosomes
Nucleus disappears
Spindle fibers appear
Phase 2: Metaphase (M= Middle)
Spindle fibers move the
duplicated chromosomes
into the middle of the cell
Phase 3: Anaphase (A=Apart)
Duplicated chromosomes
split at the centromere
Spindle fibers pull
chromosomes to opposite
sides of the cell
Phase 4: Telophase (T= Tear/Two Nuclei)
Chromosomes uncoil into
chromatin
Nucleus reappears
Spindle fibers disappear
Cytokinesis
THINK! – What happens?
Cytoplasm and organelles divided (cell splits)
Cytokinesis: Animal vs. Plant
Animal Cells
Cell membrane pinches inward
Plant Cells
Hard Cell plate forms in center
Visualizing Mitosis!
ACTIVITY
INTERACTIVE ACTIVITY TO TRY WITH THE CLASS!
Mitosis Hybrid Medical Animation
http://hybridmedicalanimation.com/anim_mitosis.html
Mitosis with Music
http://www.loci.wisc.edu/outreach/bioclips/CDBio.html
Brain-Pop Clip (Mitosis)
http://glencoe.mcgraw-hill.com/sites/007877800x/student_view0/brainpop_movies.html#
Streaming Animations
Glencoe Mitosis Animation
United Streaming (Mitosis_ 1:18)
Real-Time Animations
Animal Cell Mitosis (Just click on “LIVE ANIMAL MITOSIS”)
http://iknow.net/CDROMs/cell_cdrom/index.html
Plant Cell Mitosis (Just click on “PLANT CELL MITOSIS”)
http://iknow.net/CDROMs/cell_cdrom/index.html
Helpful Websites
Cells Alive - http://www.cellsalive.com/mitosis.htm
Biology Corner http://www.biologycorner.com/bio1/cellcycle.html