THE CELL CYCLE Flashcards
The human body must…
Precisely regulate the mitotic division of its adult stem cells to function as a coherent biological system
Defective mitotic cell division can result in…
Abnormal cell growth and metastatic cancer
What is the eukaryotic cell cycle?
The sequence of events the cell experiences from the time it is produced by the mitotic division of its parent cell until the time it divide to produce two daughter cells
Divides
Reproduces
Cell cycle duration for human adult stem cells and mature liver cells?
-24 hours for human adult stem cells
-1 year for mature liver cells (what allows the liver to regenerate)
Interphase is comprised of
-G1: first gap
-S: synthesis
-G2: second gap
What is the purpose of interphase?
It prepares the cell to reproduce by mitotic cell division
G1 duration
~10 hours
G1
-Commit to reproduce
-Begin organelle duplication
-Build more ribosomes to increase protein synthesis capacity
-Begin protein duplication
-Begin doubling cell size
-Synthesize deoxyribonucleotides and histones to support DNA synthesis during the next phase
When does the G0 phase occur?
When the cell exits the cell cycle and is not preparing to reproduce
When do adult stem cells in the G0 phase re-enter the cell cycle at the G1 phase?
When the body needs a new supply of cells
Cells in G0 phase…
Perform their bodily functions
Before S phase
The nucleus has 46 DNA molecules
After S phase
The nucleus has 92 DNA molecules to ensure that each daughter cell inherits 46 DNA molecules
Each chromosome and sister chromatid contains a
DNA molecule
When does DNA replication occur?
During S phase
DNA replication during S phase
-DNAP replicates (synthesizes) all 46 DNA molecules in the nucleus to ensure that each daughter cell inherits 46 DNA molecules
-The DNAP enzyme complex uses the rules of complementary base pairing to copy each strand of the DNA double helix
G2
-All the remaining preparations required to reproduce are completed
-Ensures DNA synthesis was completed accurately
-All organelles and biological molecules are duplicated
-Cell size doubles
-Defective organelles and biological molecules are repaired
-Spindle formation begins
How is the spindle formed?
Tubulin proteins are synthesized
The spindle moves the ________ during what phase?
Chromosomes; M phase
The G2 phase ended, the adult stem cell is
Prepared to reproduce and will enter the mitotic phase and reproduce by mitotic cell division
What does mitotic cell division consist of?
Mitosis and cytokinesis
After mitosis…
The cell has two nuclei and each nucleus has 46 DNA molecules
During cytokinesis…
The cell separates to form two daughter cells
