Download chromosomes - Ms. Dooley`s Science Class

Materials move through cells by diffusion. Oxygen and food move into cells,
while waste products move out of cells. How does the size of a cell affect how
efficiently materials get to all parts of a cell?
Work with a partner to complete this activity
1. On your bell work, make a drawing of a cell that has the following
dimensions: 5 cm x 5 cm x 5 cm. Your partner should draw another cell about
one half the size of your cell on their own bell work paper.
2. Compare your drawings. How much longer do you think it would take
to get from the cell membrane to the center of the big cell than from the
cell membrane to the center of the smaller cell?
It would take twice the amount of time.
3.What is the advantage of cells being small?
If cells are small, materials can be distributed to all parts of the cell quickly.
Image from: http://www.bcps.org/offices/lis/models/life/images/grow.JPG
CELL GROWTH
& DIVISION
10-1 & 10-2
Image by Riedell
Cell Reproduction
• Cell Theory states that
all cells come from
pre-existing cells
• Cells reproduce by cell
division
• Cells are constantly
wearing out and are
replaced by cell
division
2 Reasons why cells divide
DNA OVERLOAD
1. _____________________
As cell grows bigger demand on DNA
“genetic library” becomes too great
Ex: Small town library has 1000 books.
As town grows and more people
borrow books, there may be a
waiting list to read the
most popular titles
http://www.adc.state.az.us/images/Off-Library.JPG
2 Reasons why cells divide
Material exchange can’t keep up
2. _____________________
As cell grows bigger demand for
transport across membrane is too
great
http://www.animationlibrary.com
Ability to transport of oxygen,
food, waste across cell membrane
depends on _______________
SURFACE AREA
Need for these depends on
CELL VOLUME
___________
As cell grows these DON’T increase at the
same rate
See relationship
between volume and SA
Ratio of Surface Area to Volume in Cells
Section 10-1
Cell Size
Surface Area
(length x width x 6)
Volume
(length x width x height)
Ratio of Surface Area
to Volume
Go to
Section:
BIGGER CELLS NEED MORE FOOD
and OXYGEN, but CAN’T TRANSPORT
IT FAST ENOUGH or IN BIG
ENOUGH QUANTITIES!
http://www.animationlibrary.com
Image from: http://www.bcps.org/offices/lis/models/life/images/grow.JPG
Image by Riedell
Multicellular organisms grow
mainly by increasing cell number
Reproduction: Not as simple as it looks.
Reproduction presents a major problem for cells and organisms:
(how can information be transmitted faithfully to progeny)
= one bit of
genetic information
I
II
III
IV
The information transfer problem becomes more challenging as
more bits of information are incorporated into the organism
= one bit of
genetic information
One of life’s solutions to this challenge: “Package” the
bits of information into single units called chromosomes
= one bit of
genetic information
© 2003 John Wiley and Sons Publishers
Fig 2.4 The structure of a highly condensed, replicated chromosome.
DNA CAN BE:
SPREAD OUT IN
NON-DIVIDING
CELLS
CHROMATIN
SCRUNCHED UP
IN DIVIDING
CELLS
CHROMOSOMES
Packaging of genetic material in prokaryotes and eukaryotes
prokaryote cell
eukaryote cell
chromosomes
DNA in PROKARYOTES
• BACTERIAL DNA is CIRCULAR
• HAVE ONE CHROMOSOME
• NO NUCLEUS;
ATTACHED TO CELL MEMBRANE
http://www.origin-life.gr.jp/3202/3202121/fig6.jpg
CELL DIVISION in PROKARYOTES
Bacteria reproduce using
BINARY FISSION
__________________________________
http://fig.cox.miami.edu/~cmallery/150/mitosis/fission.jpg
DNA in EUKARYOTES
(Plants & Animals)
• DNA is ROD-SHAPED CHROMOSOMES
• MANY PAIRS
• FOUND IN NUCLEUS
http://cellbio.utmb.edu/cellbio/chrom2.jpg
CELL CYCLE
______________ = a
series of events that cells go
through as they grow and
develop;
Cell Cycle takes 18-24 hours
Organs which need to
produce new cells
continuously have the
highest turnover.
For example:Bone marrowproducing replacement
blood cells
The testes producing
semen
The cell cycle.
© 2003 John Wiley and Sons Publishers
Figure 10–4 The Cell Cycle
Section 10-2
G1 phase
M phase
S phase
G2 phase
Go to
Section:
CELL CYCLE
INTERPHASE – non-dividing phase
G1- Grow bigger
Cell is “doing its job”
DNA is spread out as chromatin
S - Synthesis (copy DNA)
& chromosomal proteins
G2- Grow bigger, make organelles &
molecules needed for cell division
CELL DIVISION
M Stage = MITOSIS = Nuclear division
• Prophase
• Metaphase
•
Anaphase
•
Telophase
• Cytokinesis = Cytoplasm divides
G0 – cell stops dividing
(Ex: nerve cell)
INTERPHASE (G1 - S - G2)
In between divisions
•Cells are in this phase most of the time
•Can see nucleus or chromosomes
•DNA spread out as chromatin…
•DNA gets copied
•Organelles get copied
Pearson Education Inc publishing as Pearson Prentice Hall
PROPHASE
=1st dividing phase
http://www.life.uiuc.edu/plantbio/102/lectures/08mit&veg102.html
•DNA scrunches into chromosomes
•Centrioles appear in centrosome region
& move to poles
•Nuclear membrane & nucleolus disappear
•Spindle fibers form & attach to
chromosomes
The Spindle
A spindle is a web type structure made up of
microtubule fibres. It is essential for mitosis
because it arranges the chromosomes into their
correct positions in preparation for cell division.
Mitotic centr
A cell at
metaphase
Microtubul
e
a spindle
CENTROSOME
________
region organizes spindle
Spindle MICROTUBULES are part of cytoskeleton
http://www.coleharbourhigh.ednet.ns.ca/library/organelle_worksheet.htm
METAPHASE
•Chromosomes line up in
middle
___________
Images from:
Pearson Eduction Ince; Publishing as Pearson Prentice Hall
http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG
ANAPHASE
•Centromeres split
apart
•Centrioles pull chromatids_______
Images from:
Pearson Eduction Ince; Publishing as Pearson Prentice Hall
http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG
TELOPHASE (reverse prophase steps)
two
•See ______
nuclei
•Nuclear membrane & nucleolus return
•Chromosomes spread out as chromatin
•Centrioles disappear
•Spindle fibers disappear
Images from:
Pearson Eduction Ince; Publishing as Pearson Prentice Hall
http://www2.bc.cc.ca.us/cnewton/Biology%2011/Mitosis.html
CYTOKINESIS = division of the
cytoplasm to create 2 cells
*ANIMAL CELLS pinch cytoplasm in two
with a ______________________
CLEAVAGE FURROW
*PLANT CELLS can’t pinch because
CELL WALL
they have a sturdy ____________
*Plant cells separate cytoplasm by
CELL PLATE
growing a _______________
down the middle.
http://www.eastcentral.edu/acad/depts/BI/plant_mitosis_nolabels.html
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
REMEMBER!
Interphase
Prophase
Metaphase
Anaphase
Telophase
Go to
Section:
IPMAT
Concept Map
Section 10-2
Cell Cycle
includes
is divided into
Go to
Section:
is divided into
Concept Map
Section 10-2
Cell Cycle
includes
Interphase
M phase
(Mitosis)
is divided into
is divided into
G1
phase
Go to
Section:
S phase
G2 phase
Prophase
Metaphase
Anaphase
Telophase