Download Cell Cycle and Division

Cell Cycle
and Division
Chapter 8
Why Do We Have So Many
Cells?
1. DNA limits cell size
- Only so much DNA can
code for proteins
2. Surface-to-Volume Ratio
-double the cell size =
double the nutrients
3. Repair or Replace Tissue
Cell Division = Mitosis!
Mitosis
– cell division where
two daughter cells are
formed, identical to parent
cell
Cell Cycle – sequence of
growth and division for the
cell
Interphase
Phases of Mitosis
Interphase
– longest cycle –
growth period
G1 Phase – high protein
production, cell grows
S Phase – DNA replicates
G2 Phase – cell organelles
duplicate
Prophase
Phases of Mitosis
Prophase
– nuclear membrane
breaks down, chromosomes
become visible, spindle fibers
form
First and longest phase of
mitosis
Prophase Terms
 Chromatin
– DNA and protein that
make chromosomes
 Chromatid – new copy of a single
chromosome strand
 Sister Chromatid – two halves of the
chromatin – identical
 Centromere – center of where sister
chromatids are held together
 Centrioles – microtubes that divide
chromatid
Metaphase
Phases of Mitosis
Metaphase
– spindle fibers
attach to sister chromatids,
sister chromatids line up in
the middle of the cell
Anaphase
Phases of Mitosis
Anaphase
– centromeres
split apart and spindle fibers
pull chromatids to opposite
sides of the cell
Telophase
Phases of Mitosis
Telophase
– chromosomes
unwind, spindle fibers break
down, and two nuclei form
Cytokinesis
Cytokinesis
Cytokinesis
– cytoplasm
division
Plant cells – a cell plate forms
around the cell then splits.
Animals cells – pinch apart
Plant Cell Cytokinesis
Results of Mitosis
Genetic
Continuity
2 New Identical Cells
Cells  Tissues  Organs  Organ System