Transcript The Cell Cycle

The Cell Cycle
Cellular Processes: Week 3
I Can…
I can describe the role cell division
plays in the development of multicellular organisms
 I can describe the events that occur
during the cell cycle: interphase,
mitosis, and cytokinesis.

How does this happen?
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Cell Division!!
Growth through Cell Division

Organisms grow in size by increasing
both the size and the number of their
cells.
– A single cell grows and then divides, forming two cells.
Then those two cells grow and divide, forming four…
BrainPOP: Growth and Cancer
First 1:50 minutes only for Growth
 Entire Cancer Segment.
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Mini-Lesson: Chromosomes
What’s in a nucleus?

Genetic Material!!!
– Sometimes this is in the form of
chromatin, other times its in the form of
chromosomes.
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What is chromatin?

Coiled up genetic material (DNA).
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DNA makes up Chromatin, like
thread makes up yarn
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What are chromosomes?

Coiled up chromatin.
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Chromatin makes up a
chromatid, like yarn makes a
ball of yarn
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Chromatids (2) make up
chromosomes.
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DNA and Chromosomes
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DNA
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Chromatin
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Chromatid
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Chromosome
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Mini-Lesson Quick Quiz
A.
DNA
2. Chromatin
3. Chromatid
4. Chromosome
1.
B.
C.
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D.
Is made up of coiledup chromatin.
Compared to 1 ball of
yarn.
Genetic material.
Compared to the
thread that makes up
yarn.
Is made up of two
chromatids. Can be
compared to two balls
of yarn.
Coiled up DNA. Can be
compared to yarn.
The Cell Cycle
Cell Cycle

The regular
sequence of
growth and
division that
cells undergo.
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Cell Cycle Structures
Centrioles
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Centromere
Spindle fibers
Chromatid
Chromosome
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Cell Cycle
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During the cell cycle,
a cell grows, prepares
for division, and
divides into two new
cells which are called
daughter cells.
 Each of the daughter
cells then begins the
cycle again.
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Cell Cycle
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The cell cycle has three stages:
2. Mitosis
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1. Interphase
3. Cytokinesis
Interphase

During interphase (Stage 1), the cell…
– GROWS,
– makes a COPY of its DNA,
– and PREPARES to divide into two cells
with the same DNA as the parent cell.
Interphase
Gap 1
(G1)
Growing
The cell grows to its full size and
produces copies of the
structures/organelles it needs to
function.
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Synthesis
(S)
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The cell makes an exact copy of
the DNA in its nucleus in a
process called DNA replication.
Gap 2
(G2)
Preparing for Division
The cell produces structures it
needs to divide into two cells.
Mitosis
Parent Cell (1)
During mitosis, one
COPY of the DNA
is distributed into
each of the two
daughter cells.
 During this stage
the chromatin
condenses (coilsup) to form
chromatids.

Daughter Cells (2)
Cytokinesis
During cytokinesis,
the cytoplasm
divides. The
organelles are
distributed into each
of the new cells.
 Each daughter cell
has the same number
of chromosomes as
the parent cell!

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Cytokinesis
In plant cells…
The cell membrane
squeezes together around
the middle of the cell. The
cytoplasm pinches into
two.
Because the hard cell wall
cannot “squeeze” together,
plant cells have a cell plate
form across the middle of
the cell. The cell plate will
develop into the membrane.
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In animal cells…
In short…

The cell cycle is how you get from 1
cell to 2 cells (and then 2 cells to 4
cells…)…
Unfortunately, cell
division is more
complicated than it
seems---there are 3
stages to go through
before you get 2 new
cells!
I Can…


I can describe the stages of
mitosis.
I can describe the product of
mitosis
The Cell Cycle and Mitosis
Mitosis

Scientists divide
mitosis into four
parts, or phases:
1.
2.
3.
4.
Prophase
Metaphase
Anaphase
Telophase
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Prophase
Chromatin in the
nucleus condenses to
form chromosomes.
 The pairs of
centrioles move to
opposite sides of the
nucleus.
 Spindle fibers form
a bridge between the
ends of the cell.
 The nuclear envelope
breaks down.

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Metaphase
The chromosomes
line up across the
center of the cell.
 Each chromosome
attaches to a
spindle fiber at its
centromere.
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Anaphase
The centromeres
split.
 The two chromatids
separate, and each
chromatid becomes a
new chromosome.
 The new
chromosomes move
to opposite ends of
the cell.
 The cell stretches
out as the opposite
ends are pushed
apart.
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Telophase


The chromosomes
begin to stretch
out and lose their
rod-like
appearance.
A new nuclear
envelope forms
around each region
of chromosomes.
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What is the product of
mitosis? FINISH

START
(Mitosis)
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Two daughter
cells with
identical DNA!
Mitosis Rap
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I is for Interphase is step 1, the step before
mitosis has begun
P is for Prophase is step 2, the chromosome double
dog that’s what they do.
M is for Metaphase is step 3, the chromosomes
line up as you can see.
A is for Anaphase is step 4, as chromosomes move
away from the core.
T is for Telephase is step 5, right, two daughter
cells are made in both of our life.
Mitosis tells all my cells to divide, each cells put
chromosomes to opposite sides. It makes daughter
cells that are two of a kind, two of a kind.
BrainPOP: Mitosis and Cell
Cycle Activity.
Cell Cycle in Plant Cells
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Interphase
Prophase
Metaphase
Anaphase
Telophase
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Which stage is
each letter in?
A
B
C
D
E
F
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I Can…
I
can describe the structure of
DNA.
 I can describe the process of
DNA replication that occurs
during interphase.
The Structure of DNA

If you were to
unravel a
chromosome, you
would find that the
DNA strands are
wound tightly
around proteins.
(The proteins help
support the
chromosome’s
structure).
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Vocabulary
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DNA (de-oxy-ribo-nu-cle-ic acid)
Double Helix
Deoxyribose (a type of sugar molecule)
Phosphate Group (a type of molecule)
Nitrogen Base (a type of molecule)
Adenine
Guanine
Thymine
Cytosine
Nucleotide
DNA

Deoxyribonucleic Acid, or DNA, is the
genetic material that carries
information about an organism and is
passed from parent to offspring.
The Structure of DNA
The strands of a
DNA molecule
look like a
twisted ladder.
 We call this
shape a “double
helix”.
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The Structure of DNA

The 2 sides of the
DNA “ladder” or
are made up of
molecules of sugar
called deoxyribose,
alternating with
molecules known as
phosphates.
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The Structure of DNA

Each “rung” of
the ladder is
made up of a
pair of
molecules
called nitrogen
bases.
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Nitrogen Base Pairs

DNA has four
kinds of nitrogen
bases:
–
–
–
–

Adenine=A
Thymine=T
Guanine=G
Cytosine=C
What do you
notice about
these bases from
the picture?
Nitrogen Base Pairs
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The bases on one
side of the ladder
pair with bases on
the other side of
the ladder.
Adenine ONLY pairs
with Thymine
Guanine ONLY pairs
with Cytosine.
Nucleotide
We say that DNA is
made up of
interconnected
molecules called
nucleotides (like beads
on a string).
 Each nucleotide has
three parts:

1. A sugar molecule:
deoxyribose
2. A phosphate molecule
3. A nitrogen base (A, T, G,
or C).
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BrainPOP and Bill Nye
DNA and Genes
DNA Replication

The process by which the cell makes
an EXACT copy of the DNA in its
nucleus.
But how does the cell make
an exact copy of its DNA?
The key is DNA’s
pairing pattern (A-T
or G-C).
 DNA replication
begins when the two
sides of the DNA
molecule unwind and
unzip like a zipper.

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But how does the cell make
an exact copy of its DNA?
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But how does the cell make
an exact copy of its DNA?
Next, nitrogen bases
that are floating in the
nucleus pair up with the
bases on each half of
the DNA molecule.
 This creates two exact
copies of the parent
DNA (because each
side is like a pattern
telling us what to add
to the other side).
