Download VOCABULARY: chromatid centromere interphase cell cycle mitosis

NOTES: 10.1 – 10.2
Cell Growth and Division
centriole
spindle
prophase
metaphase
anaphase
telophase
cytokinesis
 How
big do you think the
largest cell is?
• Yolk of ostrich egg ~8
cm in diameter
• Average cell size
range from 2-200µm
in diameter
 Why aren’t there more
large cells like the
ostrich’s?
 On
average, the cells of an adult animal
are the same size as those of a young
animal
 So what’s the difference between a young
animal and adult animal?
• The difference is that there are a lot MORE
cells in an adult animal!
 Diffusion
 DNA
 Surface
Area-toVolume Ratio
Why do you think these
factors would
influence cell size?
 Remember…the
cell membrane allows for
nutrients and gases to diffuse into and out of cell
 Diffusion is fast and efficient but only over short
distances
• As distance increases, diffusion becomes slow
and inefficient
As a cell grows in size, more demands are placed
on the cell’s DNA
● It takes time to make proteins that play a critical role
in cell function
● Ex: a small town library has enough books for people
to borrow but if a lot of people move into the town,
some people may have to wait for popular books;
DNA is like a “genetic library”

As a cell increases in size, volume
increases much faster than S.A.
 In
other words….if a cell
size were to double in
size, there would be 8
times more waste to get
rid of!
A
cell can’t get rid of
wastes that quickly…it
would poison itself!
 The
lower the SA:Volume
ratio, the harder it is to get
materials into/out of the
cell
1.
2.
3.
Interphase: longest stage; includes
preparation for cell division
Mitosis: nucleus divides into 2 nuclei, each
with the same # and kind of chromosomes
(DNA) as the parent cell
Cytokinesis: cytoplasm divides forming 2
distinct cells
 Interphase:
quite
long…
• most of the cell’s
time spent here
 Cell
Division:
occurs quickly
 G1
phase— cells GROW,
make organelles and
proteins; perform their
JOB(S)!...basically, they have
a life!
 S phase — DNA is copied
(S stands for SYNTHESIS!)
 G2 phase — more
organelles are produced than
are needed in preparation for
cell division
 MITOSIS
=
division of the
NUCLEUS
 it
stores the DNA
(information of life)
 all new cells need
this information!
 Genetic
information
is passed on from
one generation to
the next through
chromosomes
 Every
organism has a
specific number of
chromosomes
ex #1: carrots = 18
chromosomes;
ex #2: humans = 46  23
came from MOM & 23 came
from DAD
 Chromosomes
are not
visible in most cells
except in cell division
 During
interphase, the
DNA and protein
molecules that make
up chromosomes is
spread throughout the
nucleus being used to
direct cell activities /
protein synthesis
(a.k.a. CHROMATIN)
 At
the beginning of cell division, the
chromosomes condense into compact
visible structures (CHROMOSOMES)
• Before cell division (in the S phase of interphase),
each chromosome is replicated (copied)
• Each chromosome is made up of 2 identical
“sister” chromatids held together by a
centromere
CHROMOSOME
centromere
chromatin
DNA
 During
a cell’s life, its DNA is being used/
giving instructions to make proteins;
 Cell
gets too big so the cell prepares to divide;
 DNA
replicates;
 DNA
condenses into visible structures
(chromosomes);
 Chromosomes
are now ready for division!
1.
2.
3.
4.
Prophase
Metaphase
Anaphase
Telophase
 chromatin
condenses
& chromosomes
become visible
 centrioles
separate
and move to opposite
sides of the nucleus;
Centrioles:
 spindle
fibers (from
centrioles) connect to
chromosomes at their
centromeres;
 nuclear
envelope
breaks down and the
nucleolus disappears
EARLY PROPHASE
LATE PROPHASE
 **chromosomes
line up
in the center of the cell;
**fibers connect from
the poles (end) of the
spindle to the
centromere of each
chromosome
 centromeres
split, causing
the sister chromatids to
separate, becoming
individual chromosomes
 individual
chromosomes are
pulled apart to opposite
ends of the cell

chromosomes uncoil
into chromatin;

new nuclear envelope
forms around the
chromatin

spindle breaks apart

nucleolus reappears in
each new nucleus
**Often,
telophase
overlaps with
cytokinesis.
 CYTOKINESIS
= division of the cytoplasm
 in
animal cells: cell
membrane pinches in
& divides
 in plant cells: a cell
plate (new cell wall)
forms