THE CELL CYCLE AND MITOSIS
Chapter 4: Section 3
Little review here
• Why does it matter that cells can transport
materials across their cell membranes?
• Why are photosynthesis and cellular
respiration important to cells?
Thinking ahead
• Why do cells need to divide?
• 1
• 2
• 3
A few things you need to know first:
• Your DNA, actually everything’s DNA, even a
blueberry’s, is divided into lengths called
__________________________
• Different species have different numbers of
chromosomes
• The DNA that controls a certain trait, like
height, is called a ______________
• There are many genes on each chromosome
A few things you need to know first:
• Why do we care about DNA, genes and
chromosomes?
• In eukaryotes like us, we have 2 genes for each
trait –one from mom and one from dad
• These genes are on similar chromosomes—1
from mom and 1 from dad--- called homologous
(homo= __________, log = ______________)
chromosomes
The Cell Cycle
How does dividing fit into the cell’s life?
• Cell cycle = stages of the cells life
• A cell’s cycle (life) starts when it is formed (by
dividing) and ends when it divides again
What happens in between?
(Interphase)
• Cells do their jobs
How do cells divide?
• Have to make enough organelles for 2 cells
• Have to make enough DNA for 2 cells
• Have to separate and divide organelles,
cytoplasm, and DNA into 2 cells
• http://highered.mcgrawhill.com/sites/0072495855/student_view0/ch
apter2/animation__how_the_cell_cycle_work
s.html
Interphase
• Also known as the ________________ stage
• Cell is involved in growth and
________________ activities: what does that
mean?
Interphase can be broken down into 3
sub-phases
G1-
S-
G2-
Mitosis = nuclear division
4 stages
• Prophase (pro means ____________)
• Metaphase (meta means _______________)
• Anaphase
• Telophase (telo means____________)
Prophase
• DNA condenses (and
becomes visible)
• Why is this important?
Prophase
• The 2 copies of each chromosome are called
____________________________
• They are held together at the ______________
• The _____________________ breaks down
• Spindle fibers (protein strands that can get
longer or shorter) form
• ___________ move to opposite ends of the cell
Metaphase
• The double-stranded
chromatids (this means
the 2 copies of the
same chromosome line
up at the
___________________
_ of the cell
• The spindle fibers
attach to each
chromatid (and to the
centriole- that will help
them pull apart the
chromatids)
Anaphase
• The sister chromatids
_______________
___________________
• (hint for remembering:
Away and Anaphase
both start with A)
• Spindle fibers contract
and pull apart
chromatids, centrioles
help
Telophase
• The chromosomes reach
opposite sides of the cell
• The nuclear envelope
(nuclear membrane) starts
to __________________
• Spindle Fibers disappear
• The chromosomes start to
________________
Mitosis is now finished
• Do you have 2 cells
now?
• Cytokinesis:
•
http://highered.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sit
es/dl/free/0072437316/120073/bio14.swf::Mitosis%20
and%20Cytokinesis
Why is it important for:
• The DNA to divide equally?
• DNA to be coiled during mitosis?
• DNA to uncoil during interphase?
Some extra stuff: prokaryotic cells
• Prokaryotic cells divide by
_____________________
______________
• Easy because they only
have _________
chromosome
• Easy because they do not
have any
_____________________
_____________________
Some extra stuff: plant and fungi cells
• What about the cell
walls?
• During cytokinesis: a
cell plate forms and
becomes the new cell
membranes
• Then, the new cell wall
forms between the cell
membranes
When mitosis goes wrong
• Cell gets old and slow at
mitosis?
• Cell goes through mitosis
and cell division way too
much?
•
http://www.pbs.org/wgbh/nova/cancer/grows.html