Interphase Flashcards
The most basic function of the cell cycle is ..
to duplicate accurately the vast amount of DNA in the chromosomes and then to segregate the DNA into genetically identical daughter cells such that each cell receives a complete copy of the entire genome
In most cases, a cell also duplicates its other macromolecules and organelles and doubles in size before it divides; why
otherwise, each time a cell split it would get smaller and smaller
Each daughter cell can divide again by
going through another cell cycle
The duration of the cell cycle varies greatly from one cell type to another
True
Interphase is the longest phase
True
Interphase includes
S phase,g1,g2
During these gap phases
the cell monitors both its internal state and external environment.
Why
This monitoring ensures that conditions are suitable for reproduction and that preparations are complete before the cell commits to the major upheavals of S phase and mitosis
The cell-cycle control system regulates progression through the cell cycle at three main transition points.
True
At the transition from G1 to S phase
the control system confirms that the environment is favorable for proliferation before committing to DNA replication
What is G0
Resting state
At the transition from G2 to M phase
the control system confirms that the DNA is undamaged and fully replicated, ensuring that the cell does not enter mitosis unless it’s DNA is intact.
during mitosis, the cell-cycle control machinery ensures that
the duplicated chromosomes are properly attached to a cytoskeletal machine, called the mitotic spindle, before the spindle pulls the chromosomes apart and segregates them into the two daughter cells
The cell-cycle control system governs the cell-cycle machinery by cyclically activating and then inactivating the key proteins and protein complexes that initiate or regulate DNA replication, mitosis, and cytokinesis.
True
This regulation is carried out largely through the ….. of proteins involved in these essential processes
phosphorylation and dephosphorylating
The protein kinases at the core of the cell-cycle control system are present in proliferating cells throughout the cell cycle.
True
Switching these kinases on and off at the appropriate times is partly the responsibility of
Cyclins proteins
Cyclins have no enzymatic activity themselves, but they need to bind to the…. before the kinases can become enzymatically active.
cell-cycle kinases
The kinases of the cell-cycle control system are therefore known as cyclin- dependent protein kinases, or Cdks.
The cyclin that acts in G2 to trigger entry into M phase is called M cyclin, another cyclin S, help launch S phase late in G1.
True
Each of these cyclin–Cdk complexes phosphorylates a different set of target proteins in the cell
True
