Download Cell Division - Mahtomedi Middle School

CELL
DIVISION
Chapter 2, Lesson 3
Page 56
Page 56
Page 56
What Are the Functions of Cell
Division?
Read the “My Planet Diary:
Cycling On”…p. 56
Comparing Cell Cycles
The table below compares the length of different cell cycles.
WHAT ARE THE FUNCTIONS OF
CELL DIVISION?
Use the data table to
help answer the
following questions:
1. Which type of cell completes a cell cycle fastest?
Frog
egg cells
2. With each cell cycle, two cells form from one cell.
In three hours, how many cells could form from one
frog egg cell?

64 cells
SEE FIGURE 1, PAGE 57.

Label each photo as:
 (A) growth
 (B) repair, or
 (C) reproduction
Answers: A = plant shoot GROWING
B = Arm scrape healing
C = Cougar with babies - reproduction
WHAT ARE THE FUNCTIONS OF
CELL DIVISION?
Cell division allows organisms to:
GROW
 REPAIR damaged structures
 REPRODUCE

WHAT HAPPENS DURING THE
CELL CYCLE?
During the Cell Cycle, a cell grows,
prepares for division, and divides into
two new cells, which are called
“daughter cells.”
3 STAGES OF THE CELL CYCLE
The cell cycle consists of three stages:
• Interphase
• Mitosis
• Cytokinesis
“I ‘M Cool”
LOOK AT PG 58 – 62 TO HELP WITH THE
CONCEPT MAP – FILL OUT THE
OVERVIEW OF THE CELL CYCLE
The Cell Cycle
What are the 3 stages?
Interphase
What happens?
Cell
grows
DNA
gets
copied
Prophase
Prepares
for
division
Cytokinesis
Mitosis
What are the 4
phases of Mitosis?
Metaphase
Anaphase
Telophase
The Cell Cycle
What are the 3 stages?
Interphase
What happens?
Cell
grows
DNA
gets
copied
Prepares
for
division
Cytokinesis
Mitosis
INTERPHASE: TO DO LIST…PAGE 58
FILL IN A FEW THINGS YOU SEE ON THE TO-DO LIST
GROWING:
COPYING DNA:
PREPARING FOR DIVISION:
INTERPHASE – 1ST STAGE OF CELL CYCLE
MORE DETAILS…
GROWING:
 Cell grows to full size
 Produces organelles it needs
 Makes more enzymes
COPYING DNA:
 Makes an exact copy of DNA: REPLICATION
 At the end of replication, the cell has 2 identical
sets of chromosomes
PREPARING FOR DIVISION:
 Produces structures that will help it to divide

centrioles, spindle fibers, etc.
BACKGROUND OF A CHROMOSOME
P.
59 (STAGE 2: MITOSIS)
Chromosomes are
made of 2 rod-like parts
called chromatids;
chromatids are identical
to each other w/ the
same DNA.
Centromere holds
the two chromatids
together
When a cell divides,
one chromatid will
go to each new cell
The Cell Cycle
What are the 3 stages?
Interphase
What happens?
Cell
grows
DNA
gets
copied
Prophase
Prepares
for
division
Cytokinesis
Mitosis
What are the 4
phases of Mitosis?
Metaphase
Anaphase
Telophase
STAGE 2: MITOSIS
The
cell’s nucleus divides into
two new nuclei
One
set of DNA is distributed
into each daughter cell
Divided
into 4 phases:
MITOSIS HAS 4 PHASES
Prophase
Metaphase
Anaphase
Telophase
(Pandas Must Always Talk!)
PHASES OF MITOSIS
PROPHASE:
 Chromosomes in
the nucleus
condense (smash together)

Nuclear envelope
breaks down
PHASES OF MITOSIS
Interphase
How does
prophase look
different from
interphase?
Prophase
PHASES OF MITOSIS
How does
prophase look
different from
interphase?
Chromosomes
condense (the Xs); the
nucleus is changing
(nuclear envelope goes
away)
PHASES OF MITOSIS
The Cell Cycle
Cells undergo an orderly sequence of
events as they
grow and divide. What are the missing
parts of the stages?
PHASES OF MITOSIS
Metaphase:
Each chromosome
attaches to a
spindle fiber at its
centromere. What
is missing from the
cell? What
happened to the
chromosomes?
PHASES OF MITOSIS
Metaphase:
Each chromosome
attaches to a
spindle fiber at its
centromere. What
is missing from the
cell? What
happened to the
chromosomes?
The nucleus is
missing;
chromosomes
moved to the
center of the cell
PHASES OF MITOSIS
METAPHASE:


Chromosomes move
to center of the cell
Meta = middle
PHASES OF MITOSIS
Anaphase:
The centromere of
each chromosome
splits, pulling the
chromatids apart.
Each is now called a
chromosome. They
are drawn by their
spindle fibers to
opposite ends of the
cell. The cell
stretches out. Draw
the missing
structures.
PHASES OF MITOSIS
Anaphase:
Draw the missing
structures.
PHASES OF MITOSIS
ANAPHASE:

Chromatids (now
called chromosomes)
move to opposite
ends of the cell

Cell stretches out
PHASES OF MITOSIS
Telophase
How does the
diagram of a cell in
telophase look
different from the
one in anaphase?
PHASES OF MITOSIS
Telophase
Nuclei are forming;
spindle fibers have
disappeared’ cell is
pinched in around
its middle.
Telophase
How does the
diagram of a cell in
telophase look
different from the
one in anaphase?
PHASES OF MITOSIS
TELOPHASE:


Nuclei are forming
(nuclear envelope
reappears)
Cell is pinching in
at the middle
CYTOKINESIS
Stage 3
Cytokinesis
Cell splits into two
daughter cells.
Each daughter cell
has an identical set
of chromosomes.
Draw the daughter
cell.
CYTOKINESIS
Cytokinesis:
Draw the daughter
cell.
STAGE 3: CYTOKINESIS
Cytokinesis:


Cytoplasm divides
Each daughter cell
has the same
number of
chromosomes as the
parent cell
STAGE 3: CYTOKINESIS
The
cell’s nucleus divides into
two new nuclei
One
set of DNA is distributed
into each daughter cell
Divided
into 4 phases:
DO THE MATH – P. 63
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. The circle
graph to the left
displays this.
DO THE MATH – P. 63
What do the
three curved
arrows
outside of the
circle
represent?
DO THE MATH – P. 63
What do the
three curved
arrows
outside of the
circle
represent?
Interphase,
mitosis and
cytokinesis
DO THE MATH – P. 63
The wedge
representing
growth is in
which stage of
the cell cycle?
DO THE MATH – P. 63
The wedge
representing
growth is in
which stage of
the cell cycle?
Interphase
DO THE MATH – P. 63
About what
percentage of
the cell cycle
is shown for
DNA
replication?
DO THE MATH – P. 63
About what
percentage of
the cell cycle
is shown for
DNA
replication?
About 45%
DO THE MATH – P. 63
What stage of
the cell cycle
takes the
shortest
amount of
time? How do
you know?
DO THE MATH – P. 63
What stage of
the cell cycle
takes the
shortest
amount of
time? How do
you know?
Cytokinesis; it
is the smallest
section of the
graph