BELL RINGER
Explain what this
picture represents.
THE CELL CYCLE
AND
MITOSIS
HOW CELLS MAKE NEW CELLS THAT ARE IDENTICAL TO THEMSELVES
Cell Cycle- Regular pattern of growth, DNA replication and
cell division that occurs in eukaryotic cells.
Cycle is divided into 3 phases
• Interphase
• Mitosis
• Cytokinesis
Interphase
•
•
Longest phase of the cell cycle
Consists of 3 distinct periods
• Gap 1 (G1)- cell carries out normal function,
proteins are produced and organelles
multiply
• Synthesis (S)- DNA is duplicated
• Gap 2 (G2)- cell carries out normal function
and additional growth
Checkpoints
•
•
During G1 and G2 there are check points to
ensure the cell is ready to continue growth
and division.
If the cell does not meet the requirements
they move to G0- Holding tank
Mitosis- the division of the cell nucleus and its contents.
Mitosis has four stages
Chromosome- one long
continuous thread of DNA.
Chromatid- half the X of a
chromosome.
The two sister chromatid
are held together by a
centromere.
1st Stage of Mitosis- Prophase
• Chromatin forms chromosomes
• Centrioles separate and move to
opposite ends.
• Nuclear envelop breaks down
• Spindle fibers form and attach
to centromeres
2nd stage of Mitosis- Metaphase
• Chromosomes move to
center of the cell
• The site where
chromosomes gather is
called the metaphase
plate
3rd Stage of Mitosis- Anaphase
• Shortest stage of mitosis
• Spindle fibers pull apart
sister chromatids.
• Chromatids move to
opposite ends of the cell
4th Stage of Mitosis- Telophase
• End of mitosis
• Spindle fiber break apart
• Nuclear envelope re-forms
around chromosomes
• Chromosomes begin to uncoil
• 2 identical nuclei exist in the
cell
Cytokinesis
• Last stage of the cell cycle
• Division of cytoplasm after mitosis
• Results in 2 identical daughter cells
Binary Fission
This is how Prokaryotes
multiply
Lytic
Cycle
Lysogenic
Cycle
Karyotyping is a test to examine chromosomes in
a sample of cells, which help identify genetic
problems as the cause of a disorder or disease.