Test 3: Cell Cycle & Cancer Flashcards
Cell-cycle Checkpoints
Control mechanisms at key cell-cycle stages to ensure proper cell division (G1,G2, M)
Chromosomal Mutations
Errors in chromosome duplication or distribution leading to genetic changes
G1 Checkpoint
Assesses cell readiness for division, including adequate reserves and cell size, and genomic DNA damage.
G2 Checkpoint
Evaluates chromosome replication and DNA damage before mitotic entry. (Also double checks cell size and protein reserves are assessed).
M Checkpoint
Ensures correct attachment of sister chromatids to spindle fibers in metaphase
Apoptosis
Programmed cell death to prevent release of harmful molecules
Phagocytes
immune cells that engulf harmful foreign invaders and the remains of apoptotic cells
Apoptotic Bodies
Fragments of a cell undergoing apoptosis, removed by phagocytes
The timing of events in the cell cycle is controlled by mechanisms that are both __ to the cell
internal and external
Types of external cell cycle signaling (4)
death of nearby cells, growth hormone release, crowding of cells, cell hypertrophy.
Types of internal cell cycle signaling (2)
Positive & negative cell regulators
Positive regulators (cell cycle)
cyclins and cyclin-dependent kinases (CDKs); two groups of proteins
Cyclins
Proteins that are positive regulators of normal cell cycle progression through checkpoints (Cyclin A,B,C,D)
Cyclins are the __ that determine the __ of the cell cycle
main regulatory molecules; forward momentum
Cyclin-Dependent Kinases (CDKs)
Enzymes that phosphorylate proteins to advance the cell cycle
Cyclins only regulate the cell cycle when tightly bound to __.
CDKs
To be fully active, the CDK/cyclin complex must also be __ in specific locations to activate the complex
phosphorylated
Phosphorylation
Process that activates proteins by changing their shape
CDK Inhibitors
Molecules that prevent the full activation of CDKs
Negative Regulators
Molecules that stop cell cycle progression
The best understood negative regulatory molecules are __(3)
retinoblastoma protein (Rb), p53, and p21
Retinoblastoma Protein (Rb)
Tumor suppressor protein that monitors cell size and regulates other proteins by binding to transcription factors.
p53 protein
Tumor suppressor gene that monitors DNA and oxygen supply, triggering repair or apoptosis.
p21 protein
Blocks CDK activation, regulated by p53 for cell cycle control.
For the cell to move past each of the checkpoints, all positive regulators must be “turned __,” and all negative regulators must be “turned __.”
on; off
Metastasis
Spread of cancer cells to other locations in the body
Angiogenesis
Process of recruiting a blood supply to support tumor growth
Cancer
a genetic disease caused by uncontrolled cell division
Hallmarks of cancer (6)
grow and divide without external signals, insensitive to growth suppressors, resist cell death, immortality, invasion and metastasis, angiogenesis.
Genetic Disease
Cancer results from mutations in multiple genes disrupting cell cycle control
Biggest risk factor for cancer due to mutation accumulation
Age
__ are required for cancer development in __.
Multiple Mutations; specific genes.
Mutations must occur in which specific genes to develop cancer? (5)
tumor suppressor, DNA repair, cell cycle control, and growth factor, and other genes that alter the rate of growth or progression through the cell cycle.
Tumor Suppressor Genes
Negative regulators of cell cycle, prevent uncontrolled growth.
DNA Replication Errors
Small percentage passed to daughter cells, leading to mutations.
Proto-oncogenes
A positive regulator of the cell cycle in normal (non-cancer) cells
Just __ mutated proto-oncogenes develop an __ , leading to the development of cancer cells.
1; oncongenes
Oncogenes
Genes that increase cell-cycle progression rate when altered, by a change in a cyclin-dependent kinase protein such that it was active all the time.
Tumor growth is the result of __ growth of __ cells outpacing normal cells.
uncontrolled; mutated
Hypoxia
Condition of reduced oxygen supply, monitored by p53.
Cell cycle progression is controlled by __ (2)
proto-oncogenes and tumor suppressor genes.
Gene mutation starts cancer when it leads to __ in cell reproduction.
faulty proteins
Cell Cycle Control Mechanisms include __(2) to prevent errors.
redundancy and checkpoints
Loss of function in p53 may result in (2)
inability to signal DNA repair enzymes or trigger p21 production
