Transcript cp bio cell cycle mitosis powerpoint 2014

Cell Growth & Division
Question:
Why do cells divide?
•Why do we need to make
more cells?
Q: Who has
bigger cells?
A: Same cell
size,
RonRon has
MORE!
From One Cell to Many
Sea Urchin
Cell
Division
Why do we need to make more
cells?
Why are we one
hundred trillion SMALL
cells and not one
hundred LARGE cells?
100,000,000,000,000 cells because....
They need to be small!
I. Why do Cells Divide?
A. Cells need to stay small
because:
The
larger a cell becomes, the more
demands on its DNA
Trouble
moving enough nutrients and
wastes across the cell membrane
Organization!
DNA “Overload”
DNA is the cell’s “library” of information.
Imagine a very large city using one local
library for all materials
A big bag is weaker, harder to find things
Large cell,
difficult to
maneuver
organelles
More volume = bigger need
The larger the volume of
the balloon, the weaker it
is. The balloon skin stays
the same.
B. What is Surface area?
The total area of the
surface of a threedimensional object
What is the
surface area of
this cube?
24 cm2
Large surface area SPEEDS UP the
movement of materials
2 cm
2 cm
C. What is Volume?
The amount of 3-dimensional space
that an object occupies, “capacity”
Large volume SLOWS down
movement of materials
What is the
VOLUME of the
shape here?
200 cm3
cm
D. Ratio of Surface Area to
Volume
As
the length of cell increases,
volume increases faster surface area
(cm3 compared to cm2)
HIGH
ratio desired: quick movement of
materials
Ex:
6000/1 is better than 2/1
It’s better to have lots
of small cells
instead of fewer
large cells!
II. Chromosomes
A. All genes located in DNA in nucleus of
eukaryotic cell
B. Chromosomes
are condensed
forms of DNA
Chromosomes
C. Chromosome number is unique to
every species
•
•
•
•
Humans: 46 chr.
Chimpanzees: 48 chr.
Yeast: 32 chr.
Adders-Tongue Fern: 1440 chr.!
Anatomy of a
Chromosome
Chromatids attached at
the centromere
Copied during
Interphase
D. After duplication
phase, each
chromosome
consists of two
identical “sister”
chromatids
II. Cell Division
A.
46 chr
46
chromosomes
46 chr
B. Chromosome # stays the same
[Cells growths, doubles chromosomes, then splits,
forming two daughter cells with original # of
chromosomes]
C. Common Locations for Cell Division
Intestinal
Skin
Blood
lining- every 24 hours
cells/bone marrow- 120 days
Liver- sometimes
D. Cells that Rarely Divide
(In G0 phase)
Muscle Cells
Cardiac cells
Kidney
Nerve cells
III. Cell Cycle
A. Interphase: “I-ball”
90% of the time!
Gap0
Gap 1
Synthesis
Gap 2
“resting phase”, cell is not growing
cell grows, doubles organelles
duplication of the DNA in
the cell's chromosomes
cell grows, microtubules assembled
C. Checkpoints
G1 Checkpoint:
DNA to be replicated
is healthy; cell size
G2 Checkpoint:
Checks that DNA that
was replicated is
healthy; rest of cell
ready for division
M checkpoint:
Chromosomes are
properly attached to
the spindle fibers.
What happens if the cell
cannot pass through
the checkpoint?
A) Repair the damage
OR
B) Self-destruct: APOPTOSIS
(Programmed Cell Death)
There are proteins in the cell that
regulate these processes and
determine which way the cell will
go.
Now entering “M Phase”..
First stop, Mitosis!
Prophase- “pasta”
Chromatin fibers condense
 Nuclear membrane breaks down
 Spindle of microtubules forms from
centrioles [animals only]
 Attach to chromatids on centromere

Metaphase- “middle”
Chromosomes line up in the middle
 Spindle fibers attach centrioles to
centromeres
 Every sister chromatid has fiber attached to it

Centriole
Spindle
Anaphase: “away phase”, form “A’s”
Spindle fibers contract
 Pull sister chromatids apart
 The chromosomes continue to move until
they are in two groups
 Each side has own copy of DNA

Individual
chromosomes
Telophase- “end phase”
Nuclear membranes reform at each pole
 Chromosomes unwind
 Spindle disappears

Last part of “M Phase”..
Cytokinesis!
During cytokinesis, the cytoplasm cuts
in half
Cytokinesis in Plants
In plants, a structure known as the CELL PLATE
forms midway between the divided nuclei.
Cytokinesis in Animals
Animal cells contract an actin fiber across
middle of cell and “pinch” into 2 new cells- called
a “cleavage furrow”.
Twilight STUDIES IT TOO!
Parent
Cell
MITOSIS
Video Daughter
Cells
V. Terms
A. Spindle: network of microtubules that
move chromosomes during mitosis and
meiosis
B. Equator: center line of cell where
chromosomes line up during metaphase
C. Poles: the opposite ends of cell
D. Centrioles: animal cells only, move the
spindle and chromosomes during division
E. Cleavage Furrow: the pinching in of animal
cells during cytokinesis
F. cell plate: disk in plant cells that divide
the cell into two daughter cells during
cytokinesis
G. Centromere: region where two sister
chromatids are joined tightly together
“Apoptosis”:
programmed cell death
VI. Results of Mitosis
A. Production of 2 new daughter cells
B. Daughter cells are exactly the same
as original parent cell
C. Cell --> Tissue --> Organ --> Organ
System --> Organism