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What is the kinetochore?
a. The kinetochore is the button-like structure at the outer surface of the centromere of each chromatid, which assemble at the centromere at early prophase
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a. Kinetochore proteins recruited due to __
Functions: (3)
- nucleosomes containing histones
- 1.
Site of attachment of chromosome to microtubules of mitotic spindle - 2. Residence of several motor proteins involved in chromosome motility
- 3. Key component in signaling pathway of important mitotic checkpoint
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I. Formation of the Mitotic Spindle
a. Microtubule assembly in animal cells is initiated by a special microtubule-organizing structure called the __
i. After __, the microtubules of the cytoskeleton __in prep for __into the __
- centrosome
- G2
- disassemble
- reassembly
- mitotic spindle
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1. Rapid disassembly of the __ is accomplished by inactivation of proteins that __amd the aactivation of proteins that __
- interphase cytoskeleton
- stabilize microtubules
- destabilize these polymers
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a. Centrosome cycle
i. When an animal cell exits mitosis, the cytoplasm contains __ containing __ situated at right angles to each other
1. Before __finishes, the __ of each daughter cell lose their close association to one another due to the enzyme __, which becomes activated late in mitosis and cleaves a __ holding the centrioles togheter
- a single centrosome
- two centrioles
- cytokinesis
- two centrioles
- separase
- proteinaceous link
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a. Later, as DNA rep begins in the nucleus at the onset of __, each __of the __initiates its rep in the cytoplasm
i. This begins with the appearance of a small __next to each __ and oriented at right angles to it
Subsequent microtubule eleongation converts each __into a full-length daughter centriole
- S phase
- centriole
- centrosome
- procentriole
- preexisting centriole
- procentriole
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i. At the beginning of mitosis, what happens with the centrosomes?
1. The initiation of centrosome duplication at the __ is normally triggered by __of a centrosomal protein by __, the same agent responsible for the onset of DNA replication
a. __ is a tightly controlled process so that only one daughter centriole is produced
i. More can lead to mutatiosn
- the centrosome splits into two adjacent centrosomes, each with a pair of mother-daughter centrioles
- G1-S transition
- phosphorylation
- Cdk2
- Centrosome duplication
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i. The first stage in the formation of the mitotic spindle is what?
1. Microtubules grow by addition to their __, while __ remains associated with __
- appearance of microtubules in star shape, called aster, around each centrosome
- plus end
- minus end
- pericentriolar material of centrosome (PCM)
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i. Process of __ is followed by __ and __
1. Driven by __
As the centrosomes separate, the microtubules stretching between them increase in number and elongate until they reach opposite ends, establishing the two poles of a __
- aster formation
- separation of the centrosomes from one another
- movement towards opposite ends of cell
- motor proteins
- bipolar mitotic spindle
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i. Some animal cells lack __and plant cells too, but can make a __
1. The microtubules of the mitotic spindle are nucleated where rather than where?
a. Once polymerized, the __ are brought together at each spindle pole by __
- centrosomes
- mitotic spindle
- near the chromosomes
- at the poles where centrosomes would normally reside
- minus ends
- mtoor proteins
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i. Mitotic spindle is assembled in __and chromosoems are compacted in __
Interaction between the spindle and chromosomes is made possible by __ at the end of prophase
- the cytoplasm
- the nucleoplasm
- breakdown of the nuclear envelope
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What are the three components of the nuclear envelope?
i. Some membranous organelles stay intact during mitosis, like __ (4)___
- nuclear pore NP
- nuclear lamina (NL)
- membranes (NM)
- mitochondria, lysosomes, and peroxisomes, and chloroplasts of plants
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Explain the NP
disassembled as interactions between nucleoporin subcomplexes are disrupted and subcomplexes
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Explain the NL
i. NL disassembled by depolymerization of lamin filaments
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Explain the NM
i. NM: holes develop into envelope by cytoplasmic dynein molecules
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i. Debate of Golgi and ER: 3 things
- 1. Contents of Golgi are incorporated into ER during prophase, and Golgi complex ceases to exist as a separate organelle
- a. OR
- 2. Golgi fragments to vesicles that partition between daughter cells
- a. OR
- 3. Entire Golgi splits in two
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