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Cell Division
3.1 Cell Division
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Cell division occurs in all organisms, but does
different things or functions.
Unicellular organisms reproduce through cell
division.
Multicellular organisms use cell division to
grow, develop, repair themselves, and
reproduce.
Genetic Material
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The genetic material of a cell contains
information needed for the cell’s growth and
other activities.
When a cell divides into two new cells, each
cell receives a full set of genetic material.
The genetic material is contained in DNA
molecules.
DNA
DNA stands for deoxyribonucleic acid
 DNA is a molecule that contains information
for an organism’s growth and functions.
 James Watson and Francis Crick
discovered the shape of DNA and made a
model of it in 1953.
 They showed that DNA
Twists like a ladder or a
Double helix
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DNA and Chromosomes
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DNA is stored in the nucleus of a cell
DNA is wrapped around proteins to be
made smaller or more compact in
structures called chromosomes.
DNA is replicated or copied so each new cell
gets a copy.
Chromosomes
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Chromosomes consists of 2 chromatids held
together by a centromere.
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Humans have 46 chromosomes, 23 from
mom and 23 from dad
Cell Division
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Cell Division is involved in growth,
development and repair.
Through cell division a single cell becomes 2,
and then they divide into 4 cells and so on.
Even when a person, animal or plant stops
growing cell division still occurs because old
cells need replaced with new ones.
Cells don’t live forever
Throat cells only last a few days
Cell Growth
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A large organism (animal or plant) does not
have bigger cells then a smaller organism, it
simply has more cells.
Cells grow in size but there is a limit to how
big they can grow.
If cells get to big they can’t function properly
(do their jobs correctly)
Cell Development
A multicellular organism starts as a single cell
and grows into a larger one through cell
division.
 But as an organism develops each cell
specializes and takes on a specific job.
Blood cells, muscle cells etc.
 All cells have the same DNA and parts but
they perform a specific job.
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Cell Repair
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If you have ever had a cut or broken bone,
your body has repaired itself through cell
division.
As cells age and die, they need to be
replaced. Some cells last a long time and
others wear out quickly
Skin cells- age very quickly
Brain cells- live very long and don’t get
replaced often
3.1 Question: ____is a molecule that
contains the information for a cell to
grow and develop and is stored in a
nucleus.
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A. Chromosomes
B. RNA
C. DNA
D. Ribosomes
E. Water
3.1 Question: DNA is wrapped
around proteins to be made
into_____.
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A. Nucleotides
B. RNA
C. DNA
D. Ribosomes
E. Chromosomes
3.1 Question: Cell Division helps
multicellular animals to ______.
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A. get smarter
B. grow, develop, and get smarter
C. grow, develop, and repair
D. turn purple
E. reproduce
3.2 Cell Cycle
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Living things grow, reproduce, and die in a
process called a life cycle.
Cells have life cycles too, called the cell
cycle.
The cell cycle is the normal sequence of
development and division of a cell.
Cell cycle has 2 phases
Interphase and Mitosis (Cell Division)
3.2 Cell Cycle
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Interphase is the part of the cell cycle during
which a cell carries out its normal functions
and it is NOT dividing.
Mitosis is the part of the cell cycle during
which the nucleus divides.
Only eukaryotic cells go through mitosis.
The purpose of mitosis is to move DNA and
other material in position for cell division.
Cytokinesis- division of the cytoplasm and
all organelles
Interphase: normal activities
Mitosis- Division of the Nucleus
Cytokinesis- Division of cytoplasm and
other organelles
3.2 Cell Division
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Cell division produces two genetically
identical cells- they have the same DNA
If a skin cell divides you then have 2 identical
skin cells
Mitosis has 4 phases- Prophase,
Metaphase, Anaphase, and Telophase
3.2 Prophase
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The first phase of mitosis
DNA condenses (becomes smaller) into
chromosomes
The chromosomes become visible
The membrane around the nucleus breaks
down
First
3.2 Metaphase
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Second phase of mitosis
Chromosomes line up in the middle of the cell
3.2 Anaphase
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Anaphase is the 3rd phase of Mitosis
The chromosomes split and are pulled to
opposite sides of the cell.
3.2 Telophase
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Telophase is the 4th phase in mitosis
A new membrane forms around the
chromosomes to form a nucleus
Chromosomes return to their threadlike form
Recap
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Interphase- The cell is doing its daily
functions or jobs
Mitosis- Nucleus is preparing for Division
and there are 4 phases- prophase,
metaphase, anaphase, and telophase
Cytokinesis- The cytoplasm divides resulting
in 2 identical cells.
3.2 Question: ____is the part of the
cell cycle during which the cell is not
dividing and just carrying out its
normal functions.
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A. Prophase
B. Mitosis
C. Cytokinesis
D. Anaphase
E. Interphase
3.2 Question: ____is the division of
the cytoplasm at the end of mitosis.
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A. Prophase
B. Mitosis
C. Cytokinesis
D. Interphase
E. Anaphase
3.2 Question: ____ is the phase of
mitosis where the chromosomes first
appear.
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A. Metaphase
B. Prophase
C. Telophase
D. Anaphase
E. Interphase
3.2 Question: is the part of mitosis
where a new nuclear membrane forms
and chromosomes turn threadlike.
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A. Metaphase
B. Prophase
C. Telophase
D. Anaphase
E. Interphase
3.2 Question: This is the phase of
mitosis where the chromosomes line
up in the middle.
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A. Metaphase
B. Prophase
C. Telophase
D. Anaphase
E. Interphase
3.2 Question: This is the phase in
mitosis where the chromosomes
separate and get pulled to opposite
sides of the cell.
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A. Metaphase
B. Prophase
C. Telophase
D. Interphase
E. Anaphase
3.3 Cell Division for Unicellular
Organisms
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For unicellular organisms cell division
produces 2 new organisms.
This form of reproduction is called asexual
reproduction.
Asexual reproduction is where a parent
organism produces offspring that are
genetically identical to the parent.
Asexual reproduction involves one parent
3.3 Types of Asexual Reproduction
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Binary Fission is a type of asexual
reproduction and occurs when the parent
replicates it’s DNA and then splits in two.
Budding- is a process where an organism
develops tiny outgrowths called buds which
break off to form a new organism.
Regeneration- is a process in which missing
body parts are replaced. (Starfish, some
plants)
Binary Fission
Budding
Sexual Reproduction vs. Asexual Repro.
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Two parents involved
Offspring’s genes are
combined from two
parents
Reproduce more slowly
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Advantages: increased
genetic variation
Disadvantages:
slower, more energy
required, must find a
mate
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One parent organism
Offspring’s genes are
identical to parents
Reproduces quickly
Advantages: fast and
easy
Disadvantage: not
much genetic variation
3.3 Question: _____is where a parent
organism produces offspring that are
genetically identical to them.
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A. Binary Fission
B. Sexual Reproduction
C. Asexual Reproduction
D. Regeneration
E. Splitting in half
3.3 Question: _____occurs when the
parent organism replicates its DNA
and then splits in two.
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A. Binary Fission
B. Sexual Reproduction
C. Asexual Reproduction
D. Regeneration
E. Mitosis
3.3 Question: ____is the process in
which body parts can be replaced.
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A. Binary Fission
B. Sexual Reproduction
C. Asexual Reproduction
D. Mitosis
E. Regeneration
3.3 Question: ____takes longer but
results in genetically different
offspring.
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A. Binary Fission
B. Sexual Reproduction
C. Asexual Reproduction
D. Regeneration
E. Mitosis