Name: ______________________
Pd. _________
Eff. _______/5
Ch. 3 Sec. 1 Cell Division Occurs in all Organisms
-cell division occurs in all _______________, but
performs different functions.
-________________ organisms reproduce through
Cell division is involved in many functions
cell division.
-In multicellular organisms, cell division is
involved in _______________, ______________, and
repair, as well as in reproduction.
-Most growth in multicellular organisms occurs
when cells dividing produce ______________
_______________.
-genetic material for a cell contains information
needed for the cell’s growth.
The genetic material of ___________________ cells -What happens when a cell divides into two new
is organized into ___________________.
cells? ________________________________________
_____________________________________________
-genetic material in cells is contained in ________
molecules.
-DNA: _____________________________________
DNA
Chromosomes
____________________________________________
-Two scientists that built a model of DNA in 1953:
_____________ ______________ and
__________________ _________________.
-These models showed that DNA is made of
_________ strands of molecules joined in a
structure that resembles a twisted ladder or a
double helix.
-In a eukaryotic cell, most of the cell’s DNA is in
the ________________.
-While DNA is spread throughout the nucleus, the
cell performs the functions needed for
_______________. Also, during this time, DNA is
___________________.
-Chromosomes: ______________________________
____________________________________________
-Before division, chromosomes compact more and
become ________________ under a light
microscope.
-While division takes place, a duplicated
chromosome can be seen as two ________________
structures called chromatids that are held together
by a _________________.
-The ________________ of chromosomes is constant
in each species of organism.
-Example: humans have ________chromosomes.
-Like most organisms, you started out as
_______________ cells.
-Through cell division, a single cell becomes
____________ cells (cells continue to divide...2
becomes 4...4 becomes 8...etc.)
-Why does a multicellular organism grow?
Cell division is involved in _____________,
development, and ________________.
Growth
Development
_________________
__________________________________________
__________________________________________
-Even when growth and __________________
appear to stop, cell division is still occurring.
- What happens to damaged cells in an
organism? ________________________________
__________________________________________
-Example: lining of your throat has a short life
span (2-3 days)
-Large organisms have ____________ cells than
a smaller organism.
-By the time you reach adulthood, your body
will be made up of __________ _____________
cells.
-Individual cells grow in size, but there are
limits to the size a cell can reach.
-Cell division alone does not allow organisms
to _______________.
-During development, cells become specialized
to perform particular ___________________.
-Cells may take on _____________ or structures
that help them perform their functions.
-Your body repairs injuries such a cut or
broken bone by using ________________
________________.
-Example: ________________________________
__________________________________________
-Cells are ________________ at different rates.
-Skin cells replace quickly, whereas, brain cells
do not.