Mitosis

Front 1

Stages of M phase

Back 1

1. Mitosis

2. Cytokinesis (NOT mitosis)

Front 2

Dispersed Chromatin vs. Condensed chromatin

Back 2

Dispersed: easy to transcribe and replicate, hard to separate

Condensed: hard to transcribe and replicate, easy to separate

Front 3

Cohesin

Back 3

Protein enzyme to keep sister chromatin together through S and G2 phase and beginning of prophase (In interphase and mitosis)

Front 4

Method of separating sister chromatin

Back 4

phosphorylate cohesin (adds - charge), causes homologous chromosomes to lose cohesion except near centromere

Front 5

Kinetochore

Back 5

protein complex, one on either side of centromere

Front 6

Condensin

Back 6

Protein enzyme to condense DNA, appears at beginning of mitosis (NOT in interphase)

Front 7

Centromere/ Kinetochore placement

Back 7

Not always at center of mitotic chromosome

Front 8

Goal of Mitosis (Ploidy)

Back 8

Equational division, no change in n (always diploid)

Front 9

Prophase actions

Back 9

Mitotic spindle begins to form OUTSIDE of nucleus

compact mitotic chromosomes formed with kinetochores on either side of centromere

cytoskeleton, Golgi, ER, and nuclear envelope disassemble

Front 10

Prophase enzymes

Back 10

Condensin goes to work, cohesin already present

Front 11

Prometaphase actions

Back 11

Cytoplasmic MT from mitotic spindle grab KINETOCHORES (not centromere directly)

Chromosomes oscillate toward center of cell for amphitelic orientation

Front 12

Amphitelic orientation

Back 12

sisters face opposite poles

Front 13

Prometaphase enzymes

Back 13

cohesin and condensin present

Front 14

Metaphase actions

Back 14

Paired homologous sister chromosomes align along metaphase plate attached by chromosmal MT

Front 15

Metaphase enzymes

Back 15

cohesin and condensin present

Front 16

Anaphase actions

Back 16

Centromeres split and homologous sister chromatids separate, move to opposite poles of spindle

Spindle poles move apart

Front 17

Anaphase enzymes

Back 17

Splitting centromeres show that cohesin disappears

Condensin still present

Front 18

Telophase actions

Back 18

Chromosomes cluster and disperse at opposite spindle poles

Nuclear envelope, Golgi, and ER reform

No mitotic chromosomes at end of telophase

Still considered 1 cell through telophase, but has 2 nuclei

Front 19

Telophase enzymes

Back 19

Cohesin gone since Anaphase

Condensin still present but starts to disappear

Front 20

Mitotic Spindle formation

Back 20

In prophase outside of nucleus

+ end directed growth

Front 21

Pericentriolar Material

Back 21

Acts as microtubule organizational center for cytoplasmic microtubules

Front 22

Types of Cytoplasmic MT

Back 22

In prometaphase:

1. Astral MT

2. Chromosomal MT

3. Polar MT

Front 23

Astral MT

Back 23

Eminate from centrisome into cytoplasm from the aster (mitotic spindle), anchors centrisome

Front 24

Chromosomal MT

Back 24

Connects from pericentriolar material of centrisome to kinetochore

Front 25

Polar MT

Back 25

Extend from centrisome (like chromosomal MT) but attach to other polar MT instead of chromosomes

Front 26

Cytoplasmic MT growth

Back 26

Dynamic instability- if not growing, they will shrink

Front 27

2 Forms of movement Prometaphase

Back 27

1. Polymerization/depolymerization of tubulin lengthen and shorten MT

2. Cargo and rail action of motor proteins on MT (Kinesin and Dynein)

Front 28

Polymerization and Depolymerization of tubulin

Back 28

Way to position chromosomes during prometaphase

Can add or take from tubulin on both + and - end of tubulin (depending on depolymerase)

Non-ATP dependent form of movement, uses dynamic instability to move

Front 29

Consequence of inhibiting MT growth

Back 29

Cell division stops (Prometaphase cannot be completed)

Front 30

Kinesin in Prometaphase

Back 30

+ end directed growth on MT

Polar MT- sliding kinesin causes poles to move apart (controls distance between poles)

Front 31

Dynein in Prometaphase

Back 31

- end directed growth, moves mitotic chromosomes toward - end of chromosomal spindle fibers (toward centromeres)

Front 32

Colchine and Colcemid

Back 32

Metaphase Inhibitors- inhibit MT polymerization, stops chromosomes from being pulled apart in Anaphase B so chromosomes "lock" in metaphase state (homologous sister chromatids are still attached at centromere)

Inhibitors are added to cell to create karotypes

Front 33

When does a spindle checkpoint occur in the cell cycle

Back 33

In Metaphase before Anaphase

Make sure all chromosomes are lined up before they split in anaphase

Front 34

What happens when a mitotic chromosome does not reach the metaphase plate when the other 45 do?

Back 34

Spindle checkpoint: Checkpoint protein binds to the lagging chromosome causing cell cycle arrest, division stops until the chromosome catches up, the protein is removed and the cell cycle continues

Front 35

Consequences of not having a spindle checkpoint

Back 35

Genomic instability, increases risk of cancer (but does not directly cause cancer)

Front 36

Tension and cell arrest

Back 36

Adding symmetric tension can end cell arrest due to a chromosome being attached only by one spindle fiber (trick cell into continuing division)1

Front 37

Anaphase A

Back 37

Chromatids move towards the poles by shortening the chromosomal MT

POLES DON'T MOVE

No ATP needed because chromatids are easy to separate after loss of cohesin, dynamic instability moves MT without ATP

Front 38

Anaphase B

Back 38

Poles move apart as kinesin drives polar MT apart

Front 39

How would adding a kinesin inhibitor affect anaphase?

Back 39

Anaphase A would proceed normally but anaphase B would not be able to run properly