Transcript Chapter 8 Mitosis - My Teacher Pages

Mitosis and Asexual
Reproduction Notes
To be used with Mitosis and
Asexual Reproduction Guided
Notes
Cell Reproduction
• All of your body (somatic) cells are formed by mitosis
• Cell Reproduction is important when our bodies grow
or when certain cells need replacement
Cell type
Life span (days)
Brain
Red blood
Platelets
Stomach lining
Liver
Intestine lining
Skin
30-50 years
120
10
2
200
3
20
Stem Cells cells taken from an early stage embryo that
can differentiate (change into different cells)
Chromatin-Chromatid-Chromosome
Genetic material - Contains DNA
• Chromatin
DNA stands
spaghetti & meatballs
Chromatid
Coiled chromatin
Chromosome
Replicated
sister chromatids
The Cell Cycle - IPMAT
2 Parts: Interphase & Mitosis
The Cell Cycle - IPMAT
• Interphase
•
•
•
•
•
Prophase
Metaphase
Anaphase
Telophase
Cytokenesis
Interphase
• 3 parts of Interphase
– takes up about 90% of cell cycle
• G1 (growth one phase):
– organelles grow
• S (synthesis phase):
– replication of chromosome material
• G2 (growth phase two):
– more organelle and cell growth
Interphase
Chromatin:
Immature chromosomes. Chromosomes are
NOT distinguishable under microscope.
Chromatin looks like
spaghetti & meatballs.
CENTRIOLES
CHROMATIN
NUCLEAR
MEMBRANE
Mitosis - 4 phases
• Mitosis: is the second part of the cell
cycle and is a type of cell division that
results in two identical daughter cells.
– The chromosome number in the daughter
cell is the same as in the parent.
- Humans have 46 chromosomes in each
parent cell - their daughter cells will have
46 chromosomes.
– Also called asexual reproduction
or nuclear cell division
– Only one parent is needed
Mitosis
Each species has a specific chromosome number.
Organism
Human
Chimpanzee
Dog
Fruit fly
Garden pea
Adder’s fern
Number of Chromosomes
46
48
78
8
14
1260
Is the chromosome number related to the
complexity of the organism??? NO WAY!
Phase1- Prophase
1. centrioles begin to separate
2. centrioles are connected
by spindle fibers made of protein
3. nuclear membrane disappears
4. chromosomes appear coiled and
become visible
QuickTime™ and a
decompressor
are needed to see this picture.
Chromosome Structure
• chromatid: is one strand of a chromosome.
two chromatids = one chromosome
• centromere: holds the chromatids together
Phase 2 - Metaphase
1. centrioles move to opposite
poles of the cell connected
by the spindle fibers.
2. each chromosome moves
to the center of a cell along
one spindle fiber.
3. the centromere attaches to
a specific spindle fiber.
Phase 3 - Anaphase
1. cell is egg shape
2. centromeres replicate &
separate
3. chromosomes separate
4. cytoplasmic division begin
5. cell membrane begins to pinch in
Phase 4 - Telophase
1. cell shape is figure 8
2. spindle fibers disappear
3. nuclear membrane reforms
around chromosomes
4. centrioles replicate in late
telophase
5. cell division begins in late
telophase
Cytokenesis-known as complete cell division
-two identical daughter cells
The Cell Cycle:
Interphase
&
Mitosis
Mitosis
Plant Mitosis
• How does mitosis differ in plants?
– No centriole in plant cells
– Plant cells do not pinch in half
• Cytoplasmic division is accomplished by a cell
plate forming between 2 daughter cells
Mitosis In Plants: Interphase
Mitosis In Plants: Prophase
Mitosis In Plants: Metaphase
Mitosis In Plants: Anaphase
Mitosis In Plants: Telophase
Mitosis In Plants: Interphase
Results of Mitosis
1. The same chromosome number is retained
from generation to generation
2. Each daughter cell receives an exact copy
of the chromosomes of the parent cell
Results of Mitosis
3. Mutations are rare
Cancer: uncontrolled cellular
mitotic divisions
Causes: Environment influences
Viruses
Smoking
Radiation
Methods of Asexual Reproduction
• Binary fission: equal division
of the cytoplasm and nucleus
– results in two new organisms
– Examples: paramecium,
ameba, euglena
Methods of Asexual Reproduction
• Budding: nucleus of an
organism's cell divides
equally but the
cytoplasm divides
unequally
– Examples: yeast, hydra,
Sponge Bob
Sponge Bob
Methods of Asexual Reproduction
• Sporulation: the production of spores
– Example: molds
• spores: single, specialized cells which are
released from the parent
– they are enclosed in a protective case and
develop when environmental conditions are
favorable
Sporulation
Methods of Asexual Reproduction
• Regeneration: the development of an
entire new organism from part of an
original organism
– Example: starfish—one ray and part of central
body
– may also involve the restoration of lost body
parts
– invertebrates have greater powers of
regeneration than do vertebrates
Regeneration
Patrick
Methods of Asexual Reproduction
• Vegetative
Propagation:
regeneration in plants
– Complete new plants
develop from part of
the original plant
– Example: Grafting
Asexual Reproduction Summary
Individuals produced during
asexual reproduction are
genetically identical to their
parents