Transcript Mitosis + Asexual Reproduction

Why Divide?
The cell theory states that:
All cells come from other living cells.
1. Cells divide for the survival of the
individual organism
2. Cells divide for the survival of the species
(group of similar organisms)
Cells divide for the survival of the
individual organism
Cell division is used for growth, development,
maintenance, and repair of the organism.
This is carried out by:
• Mitosis- division of body cells to make more
of the same kind of cell.
–
–
•
The parent cell is the original cell inside the
organism that will divide (i.e. a skin cell)
The daughter cells are the two identical cells
created when the parent cell divides/replicates
Also a form of asexual reproduction
BASIC GENETICS
• Each cell in the human body contains two sets of 23
chromosomes (contains DNA/genetic material)
• Mitosis identically replicates this information
No genetic modifications!
• Each cell in the body therefore has
the same/identical genetic material
• Reproductive cells only have one set
of chromosomes which combine to
make a new person with different
genetic material to both parents
This is NOT through mitosis!!
Each cell has 23 different chromosomes. They’re arranged in
pairs since 1 chromosome of the pair comes from the mom,
the other from the dad. This makes a total of 46 chromosomes.
M = maternal (mom)
M P M P
P = paternal (dad)
“Pa”
P
M
1. Chromosome: coiled DNA structures
within the nucleus containing genetic
information that is passed on from
generation to generation
2. Sister Chromatid: one of two
identical “sister” parts of a duplicated
chromosome
3. Centromere (A): chromosome region
that joins 2 sister chromatids
Sister chromatids
TEM 36,000
Centromere
Cell Division: Mitosis
• Mitosis – “division of the
nucleus”. It is a synchronized
set of events that will separate
chromosomes, so that the two
nuclei formed will be identical.
• It is the beginning of cellular
division.
• (PMAT)– Prophase, Metaphase,
Anaphase, & Telophase
•
Mitosis Animation Simple
Stages of Cell Division
Interphase
- Getting ready for cell division
Mitosis
- Prophase
- Metaphase
- Anaphase
- Telophase
Cytokinesis
-Splitting cytoplasm after mitosis
-Cell growth
- DNA Replicates
(doubles the amount
of genetic material)
- Cell prepares for division
- Nuclear membrane
breaks down
- DNA coils to appear as
chromosomes
- Spindle fibers attach to chromosomes
- Centrioles separate to opposite poles
- Chromosomes line up in middle of cell
-Centromere of each double stranded chromosomes
attach to spindle fibers
- Centromeres divide and then separate
-Spindle fibers shorten pulling chromatids apart to
opposite sides of cell
- Chromosomes uncoil
-Nuclear membrane forms
around each new set of
chromosomes
- Cytokinesis begins
Cytokinesis
1. Cytokinesis is division of the
cytoplasm
2. Distributes the organelles
a. In animal cells, the cell
membrane pinches in two.
b. In plant cells, a cell plate
forms across the middle.
What Phase Of the Cell Cycle Is It?
A
Anaphase
D
Interphase
B
C
Telophase
Cytokinesis
E
F
Metaphase
Prophase
Figure 12.0 Mitosis
Figure 12.4 The cell cycle
Uses of mitosis:
Asexual Reproductions
Growth
Repair
Difference Between Plant and Animal Mitosis
Animals have centrioles, Plants cells usually do not
Animal cells divide by pinching in (Cleavage),
Plant cells divide by forming a cell plate.
Cell plate
forming
Cleavage furrow
Daughter
nucleus
Contracting ring of
microfilaments
Daughter cells
TEM 7,500
SEM 140
Cleavage
furrow
Wall of
parent cell
Cell wall
Vesicles containing
cell wall material
New cell wall
Cell plate
Daughter cells
CANCER
• is the caused by uncontrolled cellular division.
• Typically, most cells don’t divide unless it is
for repair or maintenance.
• Cancerous cells keep dividing; crowding out
and stealing nutrients from healthy tissue.
• Cancer “kills” when a mass of cancer cells
called a tumor interferes with the functions of
major organs.
Breast Cancer (uncontrolled cell growth)
Lymph
vessels
Tumor
Blood
vessel
Glandular
tissue
A tumor grows from a
single cancer cell.
Cancer cells invade
neighboring tissue.
Cancer cells spread through
lymph and blood vessels to
other parts of the body.
Cells divide for the survival of
the species 
- One parent
-Offspring genetically identical to parent cell
-will have same #chromosomes parent cell
-will have all same characteristics as parent cell
- MITOTIC CELL DIVISION
- cytoplasm and organelles split equally
Example: amoeba, paramecium, bacteria
-single circular chromosome replicates
before division
Unicellular:
Uneven division of cytoplasm and
organelles (ex. Yeast)
Multicellular: -A cell of a parent develops a
multicellular bud
- eventually bud separates becoming
separate organism (ex. Hydra)
-Mitosis with in specialized cells producing
spores.
-spore is DNA surrounded by a tough coat
(survive harsh environment)
- each spore can develop into a new organism
Example: Bread Mold
- Replacement of lost or damaged body parts
-Invertebrates show greater regenerative capacity
than vertebrates
- examples: lobster, starfish, planaria
In some cases part can grow a new organism
New plant develops from part of a parent plant
Bulbs: -Ex. Onion, Tulip
Tubers: -Ex. Potato
Runners: -stem above the ground
-new plants form where runners touches
ground (Ex. Strawberries, spider plant)
Rhizomes: -woody underground stem
-swollen regions produce new plant
(Ex. Poison Ivy, Ferns)
2n = diploid
(normal chromosome #
for species)
46
Single
2n
Chromosomes
Interphase
46
Double
2n
Chromosomes
46
2n
singles
P
M
A
T
(Mitosis)
46 Cytokinesis
2n
singles
Everyone writes statement/answer in notebook
Partner A answers: #1, Partner B answers: #2 etc.
1
1. # nuclear divisions:
2. Chromosome # (identical or different from parent cell)
Identical
3. # daughter cells created 2
4. Genetic information (identical or different from parent)
Identical
5. Uses Growth, repair, asexual reproduction
6. When are chromosomes single, double?
Single=before interphase, after telophase
Double= after interphase, until telophase
What are clones?
- Genetically identical copies
i.e. have the same traits
Hydra budding to make a clone
LM 340
Amoeba dividing asexually, making
a clone
Bacteria dividing asexually
• These are CLONES as only have
information from 1 parent
Strawberry plants making asexual
clones
• Whole new
plants grow
at the end
of the runners