470Cleavage and the Blastula

470Cleavage and the Blastula - Cleavage and the Blastula 1....

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Cleavage and the Blastula 1. Cleavage : What cytoskeletal systems and molecular motor protein is involved? -microtubule-based cytoskeleton – constructs mitotic spindle (which segregates genetic material during late anaphase) -cytoskeletal elements required for cleavage – microtubules and actin -contractile ring – made of actin microfilaments and actin-based motor protein myosin; hoop-like structure that physically pinches off the 2 daughter cells during cytokinesis - astral microtubules - microtubules that come all the way out to the cell surface (opposite the spindle); important in specifying position of the cleavage furrow -spindle microtubules - group of microtubules along which DNA moves during anaphase -the cortex, or cortical actin - actin around the outside of a cell; interacts with proteins embedded in the cell membrane which in turn interact with the extracellular matrix; seems to be necessary for cleavage furrow to form and pinch down What are the phases of the cell cycle that cleaving cells undergo? -m-phase (mitosis) -s-phase (DNA synthesis) How does the cell cycle during early cleavages differ from that of cells in the adult (somatic cells)? -somatic cell cycle -G1-S: DNA synthesis and replication -G2-M: mitosis -G1 and G2: gap phases -cleavage cell cycle – built for speed, regulated by same process as mitosis -S M S M -MPH highest during M phase, undetectable during S phase -cleavage cell cycle only uses cyclin B (mitotic cyclin) and cdc2, somatic cell cycle uses many cyclin/cdc complexes Which molecule regulates entry into m-phase (mitosis)? And how is this molecule activated? -MPF -activated MPF contains an appropriately phosphorylated cyclin-dependent kinase (ex. cdc2) and a cylcin -cyclical activity of MPF driven by cyclin B (largest subunit of MPF complex) -cyclin B regulates smaller subunit of MPF complex -cyclin synthesis activates cdc2 kinase which leade to cyclin B degradation What set of proteins does MPF activate and what repercussions does this have for the cell? -activates anaphase promoting complex which eventually leads to inactivation of MPF itself
Background image of page 1

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

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 3

470Cleavage and the Blastula - Cleavage and the Blastula 1....

This preview shows document pages 1 - 2. Sign up to view the full document.

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