Download Cell Cycle and Mitosis

Cell Cycle and Mitosis
Where you have to Divide to Multiply
Prokaryotic and Eukaryotic
Cells
Prokaryotic
organisms
include
bacteria, while
plants and
animals are
eukaryotic
Prokaryotic Cells
 Lack a nucleus
 Have a single chromosome
 Are membrane enclosed
 Have a cell wall
 Contain ribosomes
 Contain cytoplasm
 Include bacteria
Binary Fission
the reproduction of a cell or a one-celled organism by division into two
nearly equal parts
The three steps to binary fission
The cells increase their cell mass slightly
DNA & cell components are replicated
Each cell divides into two daughter cells
E. Coli is a bacteria that reproduces by
binary fission
Eukaryotic Cell
Contain a
nucleus and
membrane
bound
organelles
Asexually
reproduce cells
by mitosis
The Cell Cycle
 Purpose of the cell cycle, or
mitosis is to produce new cells for
growth and repair of dead or
damaged cells
 The stages in the growth and
reproduction of a cell are called
the Cell Cycle
 The Cell Cycle is divided into 5
stages
 Interphase which is broken down
into: G1, S and G2 phase
 Mitosis, known as the M phase
and is broken down into 4 parts
 Cytokinesis
Interphase
 Interphase is the phase where the cell spends the
majority of its time and is sometimes referred to as the
resting phase. It is divided into three phases.
 G1-is the first growth phase, the cell increases in size, carries out
normal functions and organelles duplicate
 S-synthesis phase DNA replicates; makes an exact copy of itself, the
cells instructions are contained in the DNA
 G2-second growth phase cell continues to grow and make proteins
that will be needed for mitosis; this stage is between the S phase
and the M, or mitosis phase
Interphase
Cell metabolism is occurring
Chromosomes are not visible at this stage
Mitosis
Here the cell uses it energy
to divide the nucleus
This is sometimes called
karyokinesis which means
division of the nucleus
Mitosis is divided into 4
stages
prophase
metaphase
anaphase
telophase
Prophase
Events:
•
DNA tightly coils and becomes
visible chromosomes (in humans
that is 23 pairs)
•
Duplicated chromosomes are
referred to as sister chromatids
and are connected by a
centromere
•
Nuclear membrane disappears in
order for the nucleus to divide
•
Nucleolus disappears
•
Centrioles migrate to the poles
(Here the cell is being compared
to the earth & it is opposite sides of
the cell)
•
Spindle fibers begin to form from
the centrioles
Metaphase
Spindle fibers from
centrioles attach to
each chromosome at
the centromere
Cell aligns the
chromosomes in the
middle, or equator of
the cell
Cell prepares to
separate its
chromosomes
Anaphase
• Sister
chromatids are
separated and
become
chromosomes
• Spindle fibers
shorten and pull
chromosomes
into the poles
Telophase
•
The chromosomes have
reached opposite poles
•
The nuclear membrane forms
around the chromosomes
•
The nucleolus reappears
•
Chromosomes straighten out
meaning they are no longer
coiled, condensed and visible
•
In animal cells the cell
membrane begins to pinch in
the center
•
In plant cells, a cell plate
begins to form
Cytokinesis
• This is the last phase or
stage of the cell cycle
• Means division of the
cytoplasm
• Here the cell is separated
making two identical
daughter cells
• In animal cells the cell
membrane pinches down
and cuts the two cells
apart
• In plant cells, the cell plate
cuts through the cell wall
separating the two+
And so, the multiplication of cells
resulted from the division of one cell