Post on 10-Mar-2020
The Cell Cycle/Mitosis
The cell cycle includes the process in which single cells divide to
form TWO identical cells with the SAME number of chromosomes.
• Fact: Living things grow, or increase in size. Why does this happen?
• A living thing grows because it produces more and more cells.
• If cells simply got BIGGER, they would encounter problems!
Materials will have trouble entering and leaving the cell
An “information crisis” would occur! Not enough DNA to code for all of the proteins the cell would need at a larger size.
I. Why do cells divide?
QQ1
Through what process
do materials enter and
leave the cell?
II. What is a chromosome?
• Structures in the nucleus that contain the genetic information that is passed on from one generation of cells to the next.
Chromosome Structure
• During the first stage of cell division, DNA replicates (copies itself) and condenses around histone proteins to form chromosomes.
• Each chromosome is composed of 2 identical sister chromatids attached by a centromere
QQ2
In what organelle
is the DNA found?
Interphase:
• The period between cell divisions; longest phase in the cell cycle
• Period of intense activity (interphase=intense activity)
• Divided into 3 phases: G1 (cell growth), S (DNA synthesis), G2 (organelles and materials required for cell division are synthesized)
III. Interphase Mitosis in Action
Prophase:
• Chromatin condenses into distinct chromosomes, nucleolus disappears
• Nuclear envelope begins to break down
• In animals, centrioles separate and take position on opposite sides of nucleus
• Spindle begins to form
IV. Mitosis
Metaphase:
• Chromosomes line up across the center of the cell
• Spindle fibers connect to the centromere of each chromosome
Anaphase:
• Centromeres joining the sister chromatids split
• Sister chromatids begin to separate, becoming individual chromosomes
• Anaphase ends when the movement of chromosomes stops
Telophase:
• Chromosomes begin to uncoil into a tangle of chromatin
• Spindle breaks apart
• Nuclear envelopes reform around the chromatin, forming 2 daughter nuclei
• Mitosis is complete!
QQ3
What are the 4
phases of the
mitosis?
Is Cell
Division
complete?
V. Cytokinesis
Cytokinesis:
• To complete the cell cycle, the cytoplasm needs to divide!
• Cytokinesis is the division of the cytoplasm into two individual cells with identical genetic information.
• In plants, a cell plate gradually develops into a separating membrane.
• The Cell Cycle is complete and will begin again!
QQ4
With what phase will the
cell cycle begin? What
happens during that cycle?
http://vcell.ndsu.nodak.edu/animati
ons/mitosis/movie-flash.htm
Clever ways to remember
Interphase – “Inte”nse activity.
Prophase - chromosomes first a"P"pear
Metaphase - chromosomes line up in "M"iddle
Anaphase - they move "A"way
Telophase - you have "T"wo nuclei
Cytokinesis – they divide, don’t you “C”?
iPMAT!
PMAT!
I (interphase)
prefer (prophase)
mice (metaphase)
and (anaphase)
talking (telephase)
cats (cytokinesis) QQ5
Create your own special way!