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Cells and Life Processes
Ms. De Los Rios
6th Grade
10.5 Cell Division
Essential Question:
What Are Cells Made Of?
What are the Functions of Cell Division?
What Happens During the Cell Cycle?
Pgs. 388-395
Vocabulary ch. 10.5
Cell Division- The series in which a cell grows, prepares for division, and divides to
form daughter cells.
Interphase-The first stage of the cell cycle that takes place before cell division(cell
grows and makes a copy of DNA)
Replication- The process by which a cell makes a copy of the DNA in its nucleus before
cell division.
Chromosome-A threadlike structure within a cell’s nucleus that contains DNA (passed
from one generation to the next)
Mitosis- The 2nd stage of the cell cycle. The cell nucleus divides into 2 new nuclei and
one set of DNA for each daughter cell.
Cytokinesis- the final stage of cell cycle. The cell’s cytoplasm divides, distributing
organelles into each of the two new daughter cells.
Cell Division pg. 388
Comparing Cell Cycles
The table below compares the length of different cell cycles.
What are the Functions of Cell Division?
Pg.389
Cell division allows organisms to:
1.
2.
3.
grow
repair damaged structures
reproduce.
Different ways of Cell reproduction:
• Many single-celled organisms reproduce simply through cell division.
•Other organisms reproduce when cell division leads to the growth of
new structures.
•Most organisms reproduce when specialized cells from two different
parents combine, forming a new cell.
What Happens During the Cell Cycle? P. 390
The regular sequence of growth and division that cells undergo is
known as the cell cycle.
During the cell cycle:
•The cell grows ( ---)
• Prepares for division ( / )
•Divides into two new cells “daughter cells” ( DC) and then the
cycles begins again.
The cell cycle consists of three main stages:
Interphase , mitosis, and cytokinesis.
1st Stage-Interphase,
•the cell grows
•makes a copy of its DNA, in a process
called replication.
(DNA- holds of the info. that a cell
needs to carry out its functions)
•and prepares to divide into two new
cells. Produces structures that will help
it divide in animal cells, a pair of
centrioles is duplicated
•At the end of interphase, the cell is
ready to divide.
Fig. 2 Cell Division pg. 390
Interphase: Preparing to Divide
The changes in a cell during interphase prepare the cell for mitosis.
The Cell Cycle pg. 392,3
The cell grows & produces organelles (plant=chloroplasts)
(animal=ribosomes, & mitochondria)
The replication process= cell makes an exact copy of the DNA in its
nucleus.
At the end of replication, = the cell contains two identical sets of
chromosomes, which are the threadlike structures made up of proteins
and DNA found in the nucleus.
Apply IT!!! Cell Division pg. 391
When one cell splits in half during cell division, the result
is two new cells. Each of those two cells can divide into
two more, and so on.
2nd Stage—Mitosis
2nd Stage—Mitosis= is when
the cell’s nucleus
into
2 nuclei and 1 set of DNA is
distributed to each nucleus
of each daughter cell.
Fig. 3
How does prophase look
different from interphase?
Fig. 3
There are four parts to mitosis:
1.Prophase = the replicated chromosome condense. Can shape can be
seen Microscope
2.Metaphase- The chromosomes attaches to spindle fiber @ centromere
3. anaphase – The centromere of chromosomes splits pulling chromatids
apart= single chromosome
4.Telophase- Nuclei forming- spindle fibers disappeared.
Cell Division pg. 391
Mitosis: Prophase
Mitosis begins with
prophase, which involves
further changes to the cell.
Fig.4
Cell Division
pg. 392-393
Answer all the questions and draw the missing parts of the stages in the spaces
provided.
Centriole pairs
Spindle fiber
Centromere
Chromatids
The Cell Cycle
Cells undergo an orderly sequence of
events as they
grow and divide. What are the missing
parts of the stages?
Final Stage Cytokinesis pg. 394
3rd The final stage of the cell cycle is cytokinesis.
•In animal cells, the cell membrane squeezes together around the
middle of the cell, and the cell pinches in two.
•In plant cells, a structure called a cell plate forms across the middle of
the cell and creates new cell membranes between the two daughter
cells. New cell walls then form around the membranes.
•When cytokinesis is complete, two new cells have formed, each with
the same number of chromosomes as the original parent cell.
DID YOU KNOW?? Pg. 394
Firmicutes
Certain bacteria divide only
once every 100 years! Bacteria
known as Firmicutes live in
certain rocks that are found 3
kilometers below Earth’s
surface. The life functions of
Firmicutes occur so slowly
that it takes 100 years or more
for them to store enough
energy to split in two.
Do the Math!!! Cell Division pg. 395
Length of a Liver Cell Cycle
Human liver cells generally
reproduce less than once per
year. At other times, they can
complete one cell cycle in
about 22 hours.