Download Cell Division

Cell Division
Why do you think cells divide?
Let’s Review

Before Rudolph Virchow made his
contributions to cells, there was
still debate over how new cells
came to be.

He observed new cells being made
under a microscope.

He saw that all cells come from
pre-existing cells.

He discovered cell division.
Types of Cell Division

Depending on the cell type, cell
division occurs in different ways.

Prokaryotic cells undergo Binary
Fission

Eukaryotic Cells undergo Mitosis

Reproductive Cells undergo Meiosis

We will not be learning about
meiosis just yet.
What is Binary Fission?

The division and production of
prokaryotic cells.

Binary Fission- The process results
in the reproduction of a living
prokaryotic cell by dividing into 2
parts that each have the potential
to grow to the size of the original
cell.

https://www.youtube.com/watch?
v=Th4v_Q1iHfY
https://www.youtube.com/watch?v=yiA-rHx0xGI
How Does Binary Fission Occur?

Binary Fission starts and ends in a 6 step
process:
1.
The bacteria at the start of the process is
tightly coiled.
2.
The DNA is replicated.
3.
The DNA is pulled to separate poles of the
bacteria as the cell increases in sizes and
prepare for splitting.
4.
The growth of the new cell begins to
separate the bacteria.
5.
The new cell wall fully develops, resulting
in the splitting of the bacteria.
6.
The new cells are fully separated and the
DNA coils tightly.
What is Mitosis?

The division and production of most
eukaryotic cells.

Mitosis- chromosomes in a nucleus
are separated into 2 identical sets of
chromosomes, each in its own
nucleus.

Chromosomes- DNA that is wound up
in eukaryotic cells.

Once the two nuclei are formed, the
cell will start to separate.

https://www.youtube.com/watch?v=g
wcwSZIfKlM
Events During Mitosis

Interphase- DNA is replicated and
proteins are produced.

Prophase- the nucleus fades and the
replicated chromosomes (DNA) start
to break away.

Metaphase- DNA is aligned.

Anaphase- The DNA is pulled apart
more and begin moving to cell poles.

Telophase- The two cells start
pulling apart.

Cytokinesis- The cell is completely
split.
Cool Discoveries That Support Cell
Division
Francesco Redi

An Italian scientist that lived from
1626-1697.

He made a discovery about cell
division before cell division was
created.

He was one of the first scientists to
refute a theory called
“Spontaneous Generation”

Where life of simple creatures
fleas and flies can come
spontaneously.
Redi’s Experiment

Redi placed meat in two jars ,
he put a lid on one and left the
top of one jar exposed.

He let the jars sit naturally for
a few days and observed what
happened in the jars.

The jar that did not have a lid
eventually had maggots and
those maggots hatched into
flies.

The jar that had a lid did not
get maggots.
Louis Pasteur

French scientists that lived from 18221895.

He made great discoveries in
vaccinations, fermentation, and
pasteurization (named after him).

He also did experiments to refute the
Spontaneous Generation theory.

Up until Pasteur completed his work, there
was still debate about whether or not
microbial (cell) life can form
spontaneously.
Pasteur’s Experiment

He placed broth in two flasks, and
boiled them to kill any life.

After the broths have been heated,
Pasteur broke off the lid on one of
the containers and left one lid
intact.

Over time, the broth in the
exposed flask became cloudy, a
sign that microbial life existed, but
the container with the lid
remained clear.
So What?

Redi and Pasteur’s experiments made significant impacts on our knowledge of
life and cells.

Before these scientists made these experiments, it was widely accepted that
life was a spontaneous occurrence and can happen with no assistance.

Because both of these men showed that when you deny dust and air from
entering a source, life cannot form. This disproved the accepted science that
life is a spontaneous phenomenon.

Because life is not spontaneous, all life has to come from a pre-existing source
(cell division).