About mitosis

1. CELL
DIVISION
HOW ONE CELL BECOMES TWO

2. • MOST CELLS IN ALL EUKARYOTIC ORGANISMS WILL
DIVIDE MANY TIMES THROUGHOUT THE LIFE OF THE
ORGANISM
• MITOSIS IS THE PROCESS BY WHICH A CELL DUPLICATES
ITS GENETIC MATERIALS (CHROMOSOMES AND PREPARES
FOR CELL DIVISION
• CYTOKINESIS IS THE DIVISION OF THE REST OF THE CELL
INTO TWO DIFFERENT DAUGHTER CELLS
• PROKARYOTES ALSO DIVIDE THROUGH BINARY FISSION,
BUT THIS IS NOT MITOSIS/CYTOKINESIS
• IN ANIMALS, CELL DIVISION OCCURS DURING
EMBRYONIC DEVELOPMENT, GROWTH, AND
WOUND HEALING
• ERRORS DURING CELL DIVISION CAN CAUSE CELL
DEATH OR CANCER

3. MITOSIS REORGANIZES DNA IN THE
CELL
• PRIOR TO MITOSIS, THE CELL CREATES AN EXACT
DUPLICATE OF ITS DNA MATERIAL
• DURING MITOSIS, THE TWO COPIES ARE REORGANIZED,
REPACKAGED INTO TWO SETS OF CHROMOSOMES,
AND DIVIDED TO OPPOSITE ENDS OF THE CELL
• IN MOST ORGANISMS, MITOSIS IS IMMEDIATELY
FOLLOWED BY CYTOKINESIS (THE CELL BODY DIVIDING
IN TWO)
• THE ORIGINAL CELL (MOTHER CELL) IS IDENTICAL TO THE
TWO RESULTING CELLS (DAUGHTER CELLS)

4. MITOSIS VOCABULARY
• NUCLEUS – LOCATION OF DNA INSIDE THE CELL
• NUCLEAR ENVELOPE – THE MEMBRANE THAT SEPARATES THE NUCLEUS FROM THE CYTOPLASM
• DNA – AN INCREDIBLY LONG MOLECULE THAT CONTAINS GENETIC BLUE PRINTS FOR CELL
BEHAVIOR
• CHROMATIN – A LOOSELY BUNDLED COIL OF DNA. MOST OF THE TIME, DNA IS ORGANIZED IN
THIS FORM, “ A LOOSE ROPE”
• HISTONES – PROTEINS WHICH HOLD A DNA STRAND TOGETHER IN THE FORM OF CHROMATIN
• CHROMOSOME – A HIGHLY ORGANIZED FORM OF CHROMATIN, “A TIGHTLY WRAPPED AND
CAREFULLY KNOTTED ROPE ”
• EACH CHROMOSOME IS COMPOSED OF TWO IDENTICAL PARTS CALLED CHROMATIDS
• CHROMATIDS: TWO HALVES OF A CHROMOSOME WHICH CONTAIN THE SAME GENETIC INFORMATION
• DNA EXISTS IN THE FORM OF CHROMOSOMES ONLY DURING MITOSIS
• EACH CHROMOSOME LOOKS LIKE AN X
• CENTROMERE – A BUNDLE OF PROTEINS WHICH CONNECTS THE TWO CHROMATIDS OF A
CHROMOSOME, THE “KNOT AT THE CENTER OF THE X“
• MICROTUBULES – PART OF A CELL’S CYTOSKELETON. THESE ARE TUBES OF PROTEIN WHICH USE
TO PULL CHROMOSOMES APART AND TO OPPOSITE ENDS OF A CELL DURING MITOSIS. THEY
ARE POWERED BY ATP!
• MITOTIC SPINDLE – HOW MICROTUBULES ARE ORGANIZED DURING MITOSIS. THIS IS A
COLLECTION OF MICROTUBULE FIBERS WHICH IS FORMED TO COORDINATE THE PULLING OF
APART OF CHROMOSOMES.
• METAPHASE PLATE – THE LINE ALONG WHICH CHROMOSOMES ARE LINED UP DURING MITOSIS.
THIS ARRANGEMENT IS COORDINATED BY THE MITOTIC SPINDLE.

5. CHROMOSOME STRUCTURE

6. 4 PHASES OF MITOSIS
• MITOSIS IS COMPOSED OF FOUR PHASES
• PROPHASE
• METAPHASE
• ANAPHASE
• TELOPHASE
• DURING EACH PHASE, DIFFERENT PROTEINS IN THE CELL
PERFORM SPECIFIC ROLES TO DIVIDE THE TWO COPIES
OF GENETIC MATERIAL
• CYTOKINESIS OCCURS AFTER MITOSIS TO CREATE TWO
CELLS

8. PROPHASE
• CHROMATIN IS BEING ORGANIZED
INTO CHROMOSOMES INSIDE THE
NUCLEUS
• MICROTUBULES ARE ORGANIZED
INTO MITOTIC SPINDLES IN THE
CYTOPLASM
• NUCLEAR ENVELOPE IS DISSOLVING
• BY THE END OF PROPHASE
• CHROMOSOMES AND MITOTIC
SPINDLE ARE FULLY ORGANIZED
• NUCLEAR ENVELOPE HAS
DISAPPEARED

9. PROMETAPHASE
• CHROMOSOMES MOVE TOWARDS
EACH OTHER AND INTO THE
CENTER OF THE CELL
• MICROTUBULES MOVE INTO THE
NUCLEAR REGION AND BEGIN TO
CONNECT TO CHROMOSOMES AT
THE CENTROMERE
• MICROTUBULES ORGANIZE INTO
TWO MITOTIC SPINDLES, ONE AT
EACH END OF THE CELL

10. METAPHASE
• THE MITOTIC SPINDLE IS
FULLY ORGANIZED, AND
HAS PULLING THE
CHROMOSOMES TO
THE CENTER OF THE CELL
• THE SPINDLE ALIGNS
CHROMOSOMES SO
THAT EACH
CENTROMERE IS LINED
UP ALONG THE
METAPHASE PLATE (THE
CENTER OF THE CELL)

11. ANAPHASE
• EACH CHROMOSOME IS PULLED
APART INTO TWO CHROMATIDS
(HALVES) AT THE CENTROMERE
• MICROTUBULE FIBERS
CONTRACT (USING ATP!),
PULLING CHROMATIDS TO
OPPOSITE ENDS OF THE CELL
TOWARDS THE TWO SPINDLES

12. TELOPHASE
• CHROMATIDS ARRIVE AT OPPOSITE
ENDS OF THE CELL AND BEGIN TO
UNFOLD INTO LOOSE COILS OF
CHROMATIN
• NEW NUCLEAR ENVELOPES BEGIN
TO FORM AROUND THE
CHROMATIN TO CREATE TWO
NUCLEI
• SPINDLE FIBERS DISPERSE INTO THE
CYTOPLASM
• THE CELL MEMBRANE BEGINS TO
CLEAVE IN PREPARATION FOR
CYTOKINESIS

13. CYTOKINESIS
• THE CELL MEMBRANE IS BEING PINCHED OFF TO FORM TWO
SEPARATE COMPARTMENTS
• CYTOPLASM AND ORGANELLES ARE BEING DIVIDED BETWEEN THE
TWO FORMING CELLS
• AT THE END OF CYTOKINESIS, THE MEMBRANE FUSES TO CREATE
TWO DAUGHTER CELLS WHICH CONTAIN IDENTICAL COPIES OF DNA,
AND EQUAL AMOUNTS OF CYTOPLASM AND ORGANELLES
• CELL DIVISION IS COMPLETE!

14. CELL DIVISION MOVIES
• HTTP://WWW.YOUTUBE.COM/WATCH?V=VLN7K1-9QB0
• HTTP://WWW.YOUTUBE.COM/WATCH?V=CZPGHYIGYZ8&FEATURE
=RELATED
• EMBRYONIC DIVISION IN THE WORM C.ELEGANS:
HTTP://WWW.YOUTUBE.COM/WATCH?V=ZSGOL04PESI&NR=1
• HTTP://WWW.CELLSALIVE.COM/MITOSIS.HTM