apoptosis Flashcards
(18 cards)
What is apoptosis?
It is the natural and controlled death of cells within our body.
eg. 300 million cells die every minute and are replaced by healthy cells.
What are the two pathways of apoptosis?
The two pathways are:
1. Mitochondrial (intrinsic) pathway
2. Death receptor (extrinsic) pathway
What do both pathways of apoptosis require?
Both pathways require a signal to initiate cell apoptosis and the activation of death enzymes in the cell called caspases.
What happens in the mitochondrial (intrinsic) pathway?
If there is damage inside the cell, mitochondria release cytochrome c into the cytosol, which binds with intrinsic proteins to form an apoptosome that activates caspases.
What happens in the death receptor (extrinsic) pathway?
Death signalling molecules produced by immune cells bind to death receptors on the cell membrane, activating caspases to initiate apoptosis.
What are the four stages of apoptosis?
- Activation of caspases
- Digestion of cell contents
- Cell shrinkage
- Blebbing and formation of apoptotic bodies
What occurs after apoptosis?
Immune cells called phagocytes engulf and digest the apoptotic bodies by phagocytosis.
Why is apoptosis needed for proper development?
Examples include the resorption of the tadpole tail, the formation of fingers and toes of the fetus, and the sloughing off of the inner lining of the uterus.
Why is apoptosis needed to destroy cells?
It is needed to eliminate cells infected with viruses, cells of the immune system after infections, cells with DNA damage, and cancer cells.
What is necrosis?
Necrosis is unregulated death of cells that occurs due to infection or injury, causing inflammation.
How does apoptosis relate to cancer?
If the cell cycle is disrupted, damaged cells can replicate uncontrollably, leading to tumors and cancers.
What are the two types of tumors?
The two types of tumors are benign and malignant.
What are characteristics of benign tumors?
Benign tumors are slow-growing, localized, do not spread, and are not cancerous.
What are characteristics of malignant tumors?
Malignant tumors can spread (metastasis), invade nearby tissues, and are cancerous.
What are characteristics of tumors (benign & malignant)?
- Self sufficiency in growth signals
- Antigrowth deactivation
- Increased survival
- Blood supply formation
- Tissue invasion & metastasis
What is excessive apoptosis?
Excessive apoptosis occurs when too many healthy cells are programmed to die, leading to neurological disorders.
What are some diseases linked to excessive apoptosis?
Examples include Huntington’s disease, Dementia, Parkinson’s disease, and Alzheimer’s disease.
What are the symptoms of excessive apoptosis in the brain?
Symptoms include memory loss, disorientation, personality changes, delusion, and eventual death.
