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Published on 31 Jan 2013 | over 4 years ago

The life of a cell is amazingly complex. Mitotic cell division requires precision and organization to ensure that both daughter cells receive EXACTLY the same genetic material. But how? This video explains the phases of the cell life cycle, the important structural features of chromosomes and a whole lot about microtubules which organize the whole affair. The end of the video briefly discusses how often cells divide and how they "know" when to divide - and what happens when they make mistakes.

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The Cell Cycle and Mitosis

Cell Division is needed for:
Reproduction in single-celled organisms
Asexual growth in colonial organisms
Development in multicellular organisms from a fertilized egg
Cell replacement in multicellular organisms

Challenges of Cell Division
When one cell divides into two, the daughter cells must be IDENTICAL to the parent cell
DNA management is key
Each human cell (excluding eggs or sperm) holds DNA containing 6 billion base pairs with approximately 50,000 protein-encoding genes
That DNA, if stretched out, would be 6 feet in length
Chromatin vs. Chromosome

Replication of DNA does NOT occur during mitosis! It has to occur BEFORE mitosis begins!!!

This is Your (Cell's) LIFE
The Cell Cycle
Interphase: G1, S, G2
Cell Division: Mitosis, Cytokinesis

A Little More About Chromosomes: centromere, sister chromatids, kinetochore
Moving Chromosomes Around: centrosome (spindle poles), astral microtubules, kinetochore microtubules

The Cell Cycle
Chromatin condenses into chromosomes
Nucleolus disappears
Microtubule assembly begins

Nuclear membrane breaks down
Kinetochore microtubules form and attach to kinetochores
Polar microtubules push against each other and push the centrosomes apart
Astral microtubules assemble to anchor the centrosomes at opposite poles

Chromosomes line up on the metaphase plate

Chromosomes break at the centromere into sister chromatids
Sister chromatids move toward opposite poles

Chromatids (now called daughter chromosomes) begin to decondense into chromatin
Nuclear membranes begin to form around each set of daughter chromosomes
New cell wall begins to form (plants)
Cleavage furrow forms (animals)
Cleavage (why the fascination?)

Plants and Cell Wall Formation
How Often do Cells Divide?

When Things Go Wrong... Cancer

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