Transcript Chapter 10 Cell Growth and Division

Chapter 8
Cell Growth and Division
Biology
10-1 Cell Growth
Adults don’t have bigger cells than
kids… they just have MORE of them
Why don’t cells just grow bigger?
DNA overload….DNA would need extra
copies to handle “information demand”
Too difficult to get enough nutrients
and oxygen IN and waste products OUT
The world's tallest
man in 2007 7’9”,
Bao Xishun and his
5’6” wife…
most people
with acromegalic
gigantism eventually
die because of
complications from
heart problems.
"Keeping the blood
going round such an
enormous circulation
becomes a huge
strain for the heart,"
What would happen?
Calculate ratio of surface area to volume
L * W * # of sides= surface area
L * W * H= Volume
Practice problem: if cell was a cube and
its sides were 1cm each ….figure SA?
Figure V…
What if the cell were 3cm? SA? V?
What is the ratio?
Volume increases faster than
surface area
1*1*6=6 SA
1*1*1=1 V
Ratio 6:1
3*3*6=54 SA
3*3*3=27 V
Ratio 54:27 reduce… 2:1
The decrease in ratio of SA to V- makes it
harder for the cell to move needed products
in and out.
Cell division solves…
The problem of information
storage… because each
daughter cell gets it’s own
DNA
The problem of being too
big and inefficient because
although the cell grows
some… daughter cells will
still be smaller than the
parent
10-2 Cell Division : is mitosis
4 sections of the cell cycle: G phases, S phase, mitosis,
cytokinesis
Cell Division
Mitosis
Cytokinesis
Division of the nucleus
Division
of the cytoplasm
In Bacteria …prokaryotes
Have circular DNA
And only 1 piece of DNA called plasmid
The process by which bacteria
reproduce is called binary fission (not
mitosis)
10-2 Cell Division
In eukaryotes the
chromosomes carry the
genetic information and
they live inside the
nucleus
Chromosomes are
made up of DNA and
proteins (called
histones)
Centromere is made of protein
Spindle fibers are made of microtubules
sister chromatids are duplicate halves
KaryotypeTells # of chromosomes in that body
cell
Growth & Repair
Interphase
Baby Cell (daughter cell) grows and
matures here…and eventually is
mature enough to divide
a.k.a.…time in between cell division
3 steps of Interphase
1. G1- cell grows, and makes new proteins
and organelles
2. S phase- DNA is replicated
3. G2- molecules and organelles needed for
cell division are produced.
Now ready for Mitosis
PMAT
Prophaselongest,
chromosomes
become visible/
centrioles go to the
poles
Spindle fibers start
to form
Nuclear envelope
starts to break down
Mitosis….
Metaphase (middle)
Last only a few
minutes
Chromosomes line
up across the
MIDDLE of the cell
Centromeres
connect to the
spindle fibers
Mitosis…
Anaphase (the fingers)
Centromeres split ,
splitting chromosomes
into 2 sets
Chromosomes move
away from each
other to the polesbeing pulled by
spindle fibers
Mitosis
Telophase (the peanut)
Chromosomes begin to
disappear from view
Nuclear envelope reforms
Spindles break apart
Nucleolus reforms
…end mitosis
Cytokinesis
Nucleus and contents
have split but what
about the rest of the
cell….?
Cell membrane is drawn
inward until cytoplasm
is eventually pinched
into two equal parts
In plants cell plate
eventually becomes the
cell wall
Cell plate >
http://www.biostudio.com/d_%20Mitosis.htm
10-3 Regulating the Cell Cycle
Cell growth and cell
division are carefully
controlled
Cells grow when
there is space , then
when they bump into
other cells they stop
A cut in your hand?
http://www.pearsonsuccessnet.com/snp
app/iText/products/0-13-1811185/ch10/sb4501f1.html
What signals the cell to start dividing?
A set of proteins called
cyclins control the
timing of cell division…
Internal Regulators- tell
cell to divide based on
what is happening inside
the cell (PMAT timing)
External Regulators- tell
cell to divide based on
what is happening outside
the cell (wound healing ,
embryonic development)
Cancer
A disorder in which some of the
body’s own cells (whose DNA is
damaged) lose the ability to
control growth…
Cells grow out of control and
form masses called tumors
Sometimes these cells break free and
spread throughout the body
These cells lack the proteins that tell
them to stop growing and ignore the
bordering cells telling them to stop
Causes of Cancer
Viral Infection
(commercial)
Radiation (sun, x-rays )
Smoking tobacco
Anything known to
cause cancer cells to
develop is called a
carcinogen….
Identifying the Number of
Chromosomes…
Not all living things have the same
number of chromosomes..
Humans: 46
Fruit flies: 8
Carrots: 18
**worksheet
Haploid vs Diploid
Haploid: half
Diploid: Double
But first figure out where you are at?
Body cell(regular cell) is already Diploid
Sperm/egg cell (sex cell) is already
Haploid
Differences between animal and
plant cellsPlants have a cell wall and
a cell membrane- so when
they pinch…it’s called a
cell plate.
The cell plate becomes the
cell membrane – then the
cell wall develops next. Cell plate >
The End…