Flashcards in The Cell Cycle Deck (33):
What occurs during the M phase?
the nucleus and cytoplasm divide (mitosis and cytokinesis)
What occurs during interphase?
it is the period between cell divisions (G1 phase, S phase, G2 phase)
nuclear division = ?
cytoplasmic division = ?
True or false:
As mature cells become specialized, they always continue to divide.
false; they lose the ability to divide
What phase are cells in when they do not divide?
G0: resting, cell cycle exit
What happens at G1, S and G2 phase?
G1: cellular contents other than chromosomes are duplicated
S: chromosomes are duplicated
G2: checks for errors
What is the function of the cell cycle control system?
delays later events until the earlier events are complete
What are the three major checkpoints?
1. start checkpoint (enter cell cycle and proceed to S phase)
2. G2/M checkpoint (enter mitosis)
3. metaphase to anaphase checkpoint (trigger anaphase and proceed to cytokinesis)
What are the five stages of mitosis?
prophase, prometaphase, metaphase, anaphase, telophase
During prophase, replicated chromosomes condense into...
condensin protein complexes
Mitotic spindle assembly consists of:
What happens at the end of G2?
replicated chromosomes are dispersed and tangled
At the beginning of mitosis, chromosomes condense into _______
Where are minus ends of microtubules stabilized?
What occurs during prophase? (start of M phase)
bipolar mitotic spindle assembly starts; requires disassembly and reassembly of microtubules
The centrosome MTOC consists of a pair of...
centrioles organized at right angles to each other
What is a centriole composed of?
9 fibrils of 3 microtubules each
What kind of ring complexes surround the centrosome structure?
gamma-tubulin ring complexes
What is a gamma-TuRC?
a complex of proteins that form a ring structure
The gamma-tubulin binds to the ring structure and acts as...
an attachment site for alpha and beta tubulin dimers
What does a gamma-TuRC form at the microtubule minus end?
a stabilizing cap
Where does nuclear envelope breakdown occur?
occurs at the boundary between prophase and prometaphase
What is the nuclear lamina?
meshwork of interconnected nuclear lamin proteins
What is lamin?
a special class of intermediate filaments that form a 2D lattice on the inner nuclear membrane
What triggers nuclear envelope breakdown?
phosphorylation of lamins
Which stage consists of the completion of mitotic spindle assembly?
During prometaphase, what do the chromosomes attach to?
List the three different types of microtubules involved in mitotic spindle assembly
1. astral microtubule (anchors the two poles)
2. kinetochore microtubule (attaches to chromosome; then movement starts)
3. interpolar microtubule (keeps poles apart)
Which end is associated with the spindle pole?
Microtubules from opposite poles are attached to ______ of sister chromatids
kinetochores, which are located at the centromere
How are the chromosomes oriented during metaphase?
chromosomes are aligned on the metaphase plate
What happens to the sister chromatids during anaphase?
Kinetochore microtubules lengthen or shorten?
sister chromatids separate to form two daughter chromosomes; pulled towards opposite poles