29 separation of chromosomes during anaphase requires

Info iconThis preview shows pages 29–37. Sign up to view the full content.

View Full Document Right Arrow Icon
29
Background image of page 29

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Separation of chromosomes during Anaphase requires MT motors Dynein/dynactin at centromeric region pull towards MTOC (-) end of MT spindle (spindle pole) on astral MT pull MTOC to cell periphery Kinesins connect chromosome arms to polar MT bipolar kinesin pushes polar MT apart Depolymerization at (+) and (-) end 30
Background image of page 30
Sister chromatid connected and aligned during replication Cohesin complex coats DNA keeps replicating sister chromatid in close proximity Only remain at centromere (center of chromosome) of each chromosome Cohesin complexes replaced by condensin proteins which facilitate condensation and packing of the DNA 31
Background image of page 31

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Cohesion of chromatids at centromere is tightly regulated Cohesin - multi-protein complex (smc1, smc3, and kleisin) that holds sister chromatid together; remains at centromeres Separase - enzyme that cleaves part of cohesin to release chromosomes prior to separation Securin - inhibits separase thus ensuring proper timing of chromosome separation 32
Background image of page 32
Ubiquitin-mediated protein degradation Ubiquitin- 8.5kD protein found ubiquitiously E1- Ubiquitin-activating enzyme E2- Ubiquitin conjugating enzyme E3- recognizes substrate; transfers ubiquitin to target Substrate- contains amino acid destruction sequence Proteosome- recognizes ubiquitin destruction “flag”; shreds protein 33
Background image of page 33

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
What happens when MPF is active? DNA condenses MT spindle starts to form Chromosomes align MT spindle at poles Chromosomes separate MT spindle separates DNA decondenses MT spindle disassembles 34
Background image of page 34
What happens when M-cyclin is resistant to destruction? DNA condenses MT spindle starts to form Chromosomes align MT spindle at poles Chromosomes separate MT spindle separates DNA stays condensed MT spindle remains intact 35
Background image of page 35

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
What happens when M-cyclin destruction system is overwhelmed by excessive destruction box peptides? Observation: No chromosome separation Sister chromatids remain attached Different phenotype than non-degradable M-cyclin Is there another substrate for the late mitosis destruction complex? 36
Background image of page 36
Ubiquitin-mediated protein degradation in Anaphase Degradation of proteins dictates the forward movement of the cell cycle 37 Cdh1- M-cyclin Cdc20- securin
Background image of page 37
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page29 / 37

29 Separation of chromosomes during Anaphase requires MT...

This preview shows document pages 29 - 37. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online