Transcript Cell Division and Mitosis

Cell Division and Mitosis
Why is cell division important?
 Growth
 Replacement
 Reproduction
Chromosomes
 Structure
in the nucleus that contains
hereditary information.
Cell Cycle
 Length
of time from formation of a cell
to the division of the cell.
 2 parts:
– Interphase
– Mitosis
Interphase
 The
cell:
– Grows
– Develops structures
– Copies hereditary info

Each chromosome duplicates and forms a
chromotid (pair of identical chromosomes
attached at the center by a centromere).
Mitosis
 Nucleus
divides into two identical
nuclei.
 Divided into:
–
–
–
–
Prophase
Metaphase
Anaphase
Telophase
Prophase
Pairs of chromatids are visible.
 The nucleolus disintegrates.
 The nuclear membrane disintegrates.
 In animals, two small structures, called
centrioles move to opposite sides of the cell.
 Spindle fibers begin to stretch across the cell.

Prophase
Metaphase
 Pairs
of chromatids line up across the
center of the cell.
 The centromere of each pair becomes
attached to a spindle fiber from each
side of the cell.
Metaphase
Anaphase
 Each
centromere divides.
 Spindle fibers shorten.
 Each half of the chromatid moves to
opposite sides of the cell.
Anaphase
Telophase
 Spindle
fibers disappear.
 Chromosomes uncoil.
 New nuclei form.
Telophase
Division of the Cytoplasm
 Animal
cell:
– Membrane pinches in the middle.
 Plant
cell:
– A cell plate is laid down across the center
of the cell.
– New membranes form on each side of the
cell plate.
Cytokinesis
Reproduction
 Process
by which an organism
produces others of its same kind.
 2 types:
– Sexual
– Asexual
Asexual Reproduction
 A new
organism is reproduced from one
organism.
 The new organism is genetically
identical to the parent.
 Examples:
– Potatoes
– Strawberries
Fission
 Because
bacteria do not have nuclei
they cannot reproduce through mitosis.
 During fission, the bacteria copies its
genetic information and than divides in
two.
Budding
 The
adult grows a bud.
 The bud eventually falls off and
becomes an organism.
 Ex: hydra
Regeneration
 Ability
to regrow body parts.
 If cut in “half” each part will grow into a
new organism.
 Ex: sponges, planaria, sea stars