The cell is going to divide!!??
www.bioweb.uncc.edu/biol1110/stages.
htm
www.biology.arizona.edu/cell_bio/tutori
als/cell_cycle/cells1.html
science.nhmccd.edu/biol/mitosis/pmitos
is.html
Levels of Organization
Cell
Nucleus
(animal or plant; Body or sex cell)
(Contains chromosomes)
Chromosomes (divide during cell division)
Gene
DNA
(Segment of Chromosome)
(Contains genetic information)
Vocabulary
Gamete: sex cells= sperm or egg
 Fusion of gametes forms a zygote.
 A zygote always has a full or diploid
(2n) number of chromosomes

Each species has a characteristic
number of chromosomes.

Diploid (2n) number includes two
sets of chromosomes of each type.
 Found
in all the non-sex cells or
autosomes of an organism's body
(with a few exceptions).
 Examples include humans (46),
crayfish (200), etc.
Haploid (n) number contains one
of each kind of chromosome.
 In the life cycle of many animals, only
sperm and egg cells(sex cells) have
the haploid number.
 Examples include humans (23),
crayfish (100), etc.
Types of Chromosomes:
Autosomes = Body chromosomes or
non sex chromosomes ( humans have
44 or 22 pairs)
 Sex Chromosomes = XX or XY
(23rd pair for humans) determines the
sex of the offspring

Mitosis:
the division of body cells
**Daughter
cells are
identical to
Parent cell
Parent cell
46 chromosomes
Daughter cell
46 chromosomes
Daughter cell
46 chromosomes
Remember Cell size?
1cm
If your cells
Were this size
Then
The Cell Cycle
THE CELL
CYCLE
*Interphase
*Mitosis
*Cytokinesis
Interphase
*Time in between cell division
(mitosis)
G1= Cell growth
S = DNA Replication
G2 = Prep for mitosis
Prophase
1. Chromosomes appear
condensed
2. Nuclear envelope and
nucleus disappears
3. Centrioles separate to
the poles of the cell
4. Chromosome (at their
centromeres)attach to
spindle fibers
Centromeres produce
spindle fibers
Metaphase
1. Chromosomes line
up in the equator
(center) of the cell.
(Spindle fibers help
move chromosomes
thru cell)
Anaphase
1. The centromere
splits and
chromatids
separate.
2. Chromatids move
to the poles of the
cell
Telophase
1. Chromatids start to
become diffuse
(chromatin)
2. The nuclear envelope
starts to reform
3. Nucleolus reforms
4. Spindle breaks apart
5. Cells begins splitting
Cytokinesis
* NOT a phase of mitosis
• It is a process of the cytoplasm dividing after
mitosis.
Interphase
*2 new cells are formed
*Identical to the original parent cell
THE CELL
CYCLE
*Interphase
*Mitosis
*Cytokinesis
Plant Mitosis
Onion
Root Tip
Cells
The Cell Cycle
Cell Division: Prokaryotes
The Prokaryotic Chromosome


Chromosome consists of nucleoid (an
irregularly-shaped region, electron-dense,
and not enclosed by a membrane.
Chromosome, when stretched out, is a
circular loop attached to the inside of the
plasma membrane; about 1,000 times the
length of the cell.
3. When cell is approximately twice its
original length, the plasma membrane
grows inward, a new cell wall forms
dividing the cell into two approximately
equal daughter cells.
4. Generation times of Escherichia coli
is 20 minutes; most bacteria need up to
one hour to a day.