Download Cell cycle

Cell Division
Why Cells Make More Cells
1. Most cells go through a series of changes in order
to maintain homeostasis.
2. Cells need to reproduce (divide) when their surface area
can no longer supply the much larger volume with
nutrients and get rid of wastes.
Surface Area
(length x width x 6)
Volume
(length x width x height)
Ratio of Surface Area
to Volume
Vocabulary
chromo─ color
─soma:
body
─id:
self, body
1. Chromatin: the relaxed, uncoiled
state of the chromosome
2. Chromatid: one of two identical
“sister” parts of a duplicated
chromosome
3. Chromosome: threadlike
structures within the nucleus
containing genetic information
that is passed on from generation
to generation
4. Centromere: chromosome region
that joins 2 sister chromatids
centro─
─mere:
center
part
A: centromere
B: chromatids
Chromosomes
1. Chromosomes: made up
of DNA & proteins
2. Carry the cell’s coded genetic
information
3. Different organisms have a
different number of
chromosomes
Fruit flies have 8
chromosomes in each
body cell
Humans have 46
chromosomes in
each body cell
Frogs have 26 chromosomes
in each body cell
Cell Cycle
1. Cell cycle: Sequence of events between the time a cell
divides to form 2 daughter cells & the time those 2 cells
divide
2. Consists of Interphase and
M-phase (Mitosis &
Cytokinesis)
3. G0 ─ cells that exit the cell
cycle
Interphase: 3 Phases
1. G1 phase: Growth Phase
a. Cell performs all life’s
activities: protein synthesis,
waste removal, organelle
synthesis, etc.
2. S phase: DNA Replication
a. DNA makes a copy of itself
b. Produces 2 identical sets of
chromosomes
3. G2 phase: Preparation
a. Cell produces centrioles &
spindle fibers needed to move
the chromosomes
Mitosis Discovered
Walther Flemming first discovered
mitosis in 1870 and reported is
discovery of chromosomes and
mitosis in 1882.
Metaphase in a salamander cell
drawn by Walther Flemming
from a stained slide.
Mitosis
Review
Normal red blood cells
only live for 120 days.
Then they die & stem
cells make new ones.
1. Two main stages of the M-phase
a. Mitosis: division of the nucleus
b. Cytokinesis: division of the
cytoplasm
2. Produces 2 cells called daughter cells
a. Cells are genetically identical
3. Mitosis is source of new cells for
a. Growth
b. Development
c. Repair
d. Replacement of old cells
4. Cells that go through mitosis: skin,
bone, muscle, liver
5. Cells that RARELY go through mitosis:
nerve cells
Mitosis
1. Described as movement of
chromosomes
2. Continuous series of events
3. Divided into four phases so
that it is easier to understand
Cell Cycle
Diploid verses Haploid
23
Di─
double
Haplo─ single
-oid:
like
23
Sperm cell
Egg cell
Fertilization
Haploid: 1n; 1 set of chromosomes
•The egg and sperm cell are haploid
Diploid: 2n; 2 sets of chromosomes
•The fertilized egg cell is diploid
46
Each kind of cell:
•Skin
•Muscle
•Bone
•Nerve
Fertilized
Egg cell
•Are ALL DIPLOID
All of the cells that make up
the organism are diploid
Cancer Cells
1. Normal cells contain check points to regulate
the cell cycle, & stop at appropriate check points.
2. Cancerous cells do not respond to check points
and continue rapidly through the cell cycle. This
results in masses of undefined cells called tumors.
3. Cancer cells do not mature; they become more
immature.
Do not enter into G0