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Cell cycle
A series of events that a cell goes through as it grows and divides, fundamental to growth, tissue repair, and cell replacement.
Interphase, Mitosis, and Cytokinesis.
What are the main phases of the cell cycle?
Interphase
The longest phase of the cell cycle, accounting for over 90% of total cycle time, involving growth and preparation for division.
G1 phase
Intense growth, cellular activity, protein synthesis, and checks for DNA damage and resources occurs in what phase?
DNA replication occurs, duplicating the entire genome to ensure each daughter cell receives identical chromosomes.
What happens in the S phase?
Final preparations for mitosis, production of necessary proteins, and checks for DNA replication errors.
What is the role of the G2 phase?
G0 phase
A resting state where cells exit the cell cycle and do not actively divide; this can be temporary or permanent.
To divide the nucleus, ensuring each daughter cell receives a full, identical set of chromosomes.
What is the purpose of Mitosis?
Prophase
Chromatin condenses into visible chromosomes, the nuclear membrane breaks down, and spindle fibers begin to form.
Metaphase
Chromosomes align along the metaphase plate and spindle fibers attach to their centromeres.
Anaphase
The phase where centromeres split and sister chromatids are pulled to opposite poles by spindle fibers.
Telophase
Separated chromosomes reach opposite poles, nuclear membranes reform, and chromatin begins to de-condense.
Cytokinesis
The final step of cell division where the cytoplasm is divided, resulting in two distinct daughter cells.
It checks for DNA damage, sufficient resources, and favorable environmental conditions.
What does the G1 checkpoint assess?
Checkpoints in the cell cycle
Regulatory mechanisms that assess whether key processes are completed accurately before progressing to the next phase.
That all chromosomes are properly aligned on the metaphase plate before entering anaphase.
What does the M checkpoint ensure?
They regulate the progression of the cell cycle by activating cyclin-dependent kinases (CDKs).
What role do cyclins play in the cell cycle?
Cyclin-dependent kinases (CDKs)?
Enzymes that, when activated by cyclins, drive the progression through the cell cycle.
Apoptosis
Programmed cell death that occurs when a cell is significantly damaged, preventing propagation of defective cells.
Tumor suppressor genes
Genes that produce proteins that inhibit the cell cycle or induce apoptosis in damaged cells.
Oncogenes
Mutated versions of normal genes that promote uncontrolled cell division, often associated with cancer.
Telomeres
Protective caps at the ends of chromosomes that prevent the loss of genetic material during DNA replication.
They help separate the chromosomes by attaching to centromeres and pulling chromatids apart.
What is the significance of spindle fibers during mitosis?
Chromatin
A complex of DNA and proteins that exists in a loosely coiled form within the nucleus during interphase.
Cleavage furrow
The indentation that forms in the cell membrane during cytokinesis in animal cells.
Cell plate
The structure formed during cytokinesis in plant cells that evolves into a new cell wall separating daughter cells.
External signals that promote cell division.
What is the role of growth factors?
They can lead to diseases, such as cancer, where cells divide uncontrollably.
What are the consequences of disruptions in the cell cycle regulation?
To synthesize ribosomal RNA (rRNA) and assemble ribosome subunits within the nucleus.
What is the main job of the nucleolus?
They exit the cell cycle and remain inactive, and this can be temporary or permanent depending on the cell type.
What happens to the cells in G0 phase?
Note 
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