Transcript Mitosis powerpoint

How do little elephants grow up to be BIG
elephants?
Cell Growth
›
›


Since living things grow by producing
more cells, the cells of an adult animal are
no larger than those of young animals---there are just more of them.
Limits to Cell Growth (read page 241)
1. DNA overload
2. Exchanging Materials
The process of asexual
reproduction begins after a
sperm fertilizes an egg.
Skin cancer - the abnormal growth of
skin cells - most often develops on skin
exposed to the sun.
Cell that reproduce by asexual
reproduction reproduce constantly.
The Cell Cycle

The Cell Cycle@







the cell cycle is a sequence of growth and division
there are 4 phases (Fig 10-4)
G1 = cell growth
S = DNA synthesis
G2 = prepare for cell division
M = cell division; Mitosis and
Cytokinesis
Cell Cycle Regulation
Cyclins regulate the cell cycle

Ex protein called p53
Cancer is the unregulated growth
of cells. These cells do not
respond to cyclins.


-
Cancerous cells divide uncontrollably to
form masses of cells called tumors.
Animated Mitosis Cycle
http://www.cellsalive.com/mitosis.htm
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase & Cytokinesis
Chromosomes are copied (# doubles)
• Chromosomes appear as threadlike coils
(chromatin) at the start, but each chromosome
and its copy(sister chromosome) change to sister
chromatids at end of this phase
•
Nucleus
CELL
MEMBRANE
Cytoplasm
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Interphase (Growth Period)
- cells spend most time in this phase
 - divided into 3 phases
 G1, S, G2
 Cell grows in size
 Chromosomes replicate also known as
DNA synthesis
 Cell repairs itself before division

Mitosis (Division Period; PMAT@ $)



- nucleus and cytoplasm divides to form 2
daughter cells
- occurs in all body cells
(all cells except sex which are gametes)
- Each new cell has the same number of
chromosomes as “parent” cell. This is called
diploid (2N) number of chromosomes
Example
•
•
•
Mitosis begins (cell begins to divide)
Centrioles (or poles) appear and begin to
move to opposite end of the cell.
Spindle fibers form between the poles.
Centrioles
Sister chromatids
Spindle fibers
Prophase (Prepare)

Chromosomes thicken and become
visible
›
›

chromosomes are 2 sister chromatids
connected by centromere
Fig 10-3 page 244
Example:
›
›
›
The nucleus, nuclear envelope and nucleolus
disappear.
Centrioles migrate to opposite ends of the cell in
animal cells
Spindle fibers form
Animal Cell
Plant Cell
Spindle fibers
Centrioles
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Chromatids (or pairs of chromosomes) attach
to the spindle fibers.
Centrioles
Spindle fibers
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Chromatids (or pairs of chromosomes)
separate and begin to move to opposite
ends of the cell.
Centrioles
Spindle fibers
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
•
•
Two new nuclei form.
Chromosomes appear as chromatin (threads
rather than rods).
Mitosis ends.
Nuclei
Chromatin
Nuclei
Telophase (The cell begins to split into
two; looks like telephone)
›
›
›
›
chromosomes unwind
spindle breaks down
nucleolus and nuclear envelope reappears
plasma membrane separates the 2 new nuclei

- the animal cell plasma membrane pinches in Fig
10-5 Telophase

- the plant cell forms a cell plate across the
equator Fig 10-6 pg 248
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Cell membrane moves inward to create two
daughter cells – each with its own nucleus
with identical chromosomes.
Cytokinesis
- Although mitosis is division of the
nucleus, cytokinesis is division of the
cytoplasm
 - 2 new cells are formed that are
identical to the parent cell
 - this process is asexual reproduction

Remember Events of the Cell Cycle by
IPMAT
 I = Interphase
 P = Prophase
 M = Metaphase
 A = Anaphase
 T = Telophase

Animal vs Plant Cell Division

Animal
Use centriole
Cell pinching
Plant
No centriole
Cell Plate
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
30
- Cell Division
31
31
http://www.cellsalive.com/mitosis.htm