Chapter 10 CMB Apoptosis Flashcards
*What are the 5 Major stages of the embryonic development? (FCGNO)
- Fertilization
- Cleavage
- Gastrulation
- Neurulation
- Organogenesis
What happens during fertilization?
Produces a zygote
What happens during cleavage?
Cells divide to form a Blastula
What happens during gastrulation?
Cells move and fold to form layers from which tissues are built
What happens during neurulation?
The formation of a neural tube from which the nervous system develops
What happens during organogenesis?
Initiation of organ development in the embryo
What is apoptosis?
- The process whereby cells commit suicide
- Programmed cell death
- Involves the use of specialize cellular material
*What is the function of apoptosis? (2 functions)
Enables the body to:
1. Control cell numbers in the normal development and functioning of the organism
2. Eliminate cells that threaten the organism’s survival
What are the examples of “Control cell numbers in the normal development and functioning of the organism”? (3 examples) (RSR)
Examples:
a) Removal of tissues between toes and fingers during embryonic development.
b) Sloughing off of the inner lining of the uterus at the start of menstruation.
c) Removal of surplus cells between neurons in the brain to form synapses
What are the examples of “Eliminate cells that threaten the organism’s survival?” (4 examples)
Examples:
1. Cells infected with viruses
2. Immune cells that attack the body
3. Cells with damaged DNA
4. Cancer cells
*How does apoptosis occur? (5 steps)
- Cells shrink and develop “blebs” on their surface
- DNA and protein in the nucleus degrade
- Mitochondria break down and release cytochrome C
- Cytochrome C activates enzymes called caspases
- Caspases cause the cells to burst
What is the role of apoptosis in normal and abnormal embryonic development?
- Programmed cell death (apoptosis) plays an important role in the processes of gamete maturation as well as in embryo development, contributing to the appropriate formation of various organs and structures.
- Disordered apoptosis may lead to carcinogenesis and participates in the pathogenesis of Alzheimer disease, Parkinson disease, or AIDS.
What makes a cell decide to commit suicide? (2 causes) +-
- Withdrawal of positive signals needed for continued survival of cell (For example: Interleukin 2)
- Receipt of negative signals indicating that apoptosis should occur (For example: Damaged DNA/Proteins)
What is gene control of apoptosis?
Apoptosis is regulated by genes which code for apoptosis and genes which prevent apoptosis
What are the types of gene control of apoptosis? (2 types)
- Anti-apoptotic genes (Prevent cell death)
- Pro-apoptotic genes (Causes cell death)
What is anti-apoptotic genes?
- Produce proteins that prevent apoptosis
- Bcl-2 gene
What is the Bcl-2 gene?
It is an anti-apoptotic gene and the expression of the Bcl-2 gene prevents apoptosis from occurring
What is pro-apoptotic genes?
- Produce proteins that cause apoptosis
- Bax gene
*What is the Bax gene?
It is a pro-apoptotic gene and the expression of the Bax protein leads to destruction of the mitochondria => release of cytochrome C => necrosis
How does Bax kill a cell?
- The bax gene is a “pro-apoptotic” gene. The bax protein is coded by the bax gene.
- The bax protein binds to permeability pore of the cell’s mitochondria
- Increase in permeability triggers cell death
- Mitochondria plays a role in apoptosis as it facilitates cell death through apoptosis by releasing Cytochrome C
*What are the functions of the mitochondria? (2 examples)
- Produce energy
- Facilitate cell death through apoptosis
How does apoptosis linked with cancer? (relationship)
- Over expression of anti-apoptotic genes
- (enough “don’t die” => live) - Under expression of pro-apoptotic genes
- (not enough “pro die” => live)
Either of these leads to uncontrolled cell division (growth) and can lead to cancer.
What is cancer? (3 steps)
- Cells which grow in an uncontrolled manner,
- Ultimately spreading throughout the body and,
- Interfering with the function of normal tissue and organs
What are some examples that cancer cells do not do? (4 properties) DDRG
They do not…
- Differentiate
- Die from old age (immortal)
- Respond to signals
- Grow quickly
(Note: Cancer cells do not do these things)
Cancer is a Heterogeneous Disease (Part 1)
- Cancer is the loss of control of the cell cycle
- The cell cycle is controlled by
(1. Inhibitors of the cell cycle = suppressors)
(2. Promoters of the cell cycle = oncogenes)
Cancer is a Heterogeneous Disease (Part 2)
- Most cell types of the body can become cancerous
- Cancer cells
1. Can multiply in the absence of growth-promoting signals
2. Are resistant to signals that normally program cell death (apoptosis) - Cancer cells can invade surrounding tissues and then spreading through the body to establish secondary areas of growth
- The spread of cancer cells is called metastasis
*What is the loss of control of the cell cycle?
Cancer
*How can the cell cycle be controlled? (2 examples)
- Inhibitors of the cell cycle = suppressors
- Promoters of the cell cycle = oncogenes (onco means cancer)
*What is the function of cancer cells? (2 examples)
- Can multiply in the absence of growth-promoting signals
- Are resistant to signals that normally program cell death (apoptosis)
*What is the spread of cancer cells called?
Metastasis
What are proto-oncogenes?
- Genes of undifferentiated growth
- Expressed during embryonic development
What does mutation of proto-oncogenes to oncogenes leads to? (3 examples)
- Loss of control of growth
- Failure of cells to differentiate
- Prevention of apoptosis
What are tumour suppressor genes?
- Genes that protect cell from cancer
- Necessary for apoptosis
What does mutation of tumour suppressor genes lead to?
Mutation can lead to an under expression of tumor suppression genes leading to malignant behavior
Do cancers arise from an imbalance of gene expression?
Yes
*Main causes of cancer: Generalizations (6 examples)
(Note: Remember at least 2 examples)
- Spontaneous genetic mutations
- Inherited cancer susceptibilities
- Carcinogenic substances (asbestos)
- Viruses
- Radiation
- Hormonal substances
Other, less common causes of cancer (4 examples)
- Stress
- Diet (intake of excessive fatty food)
- Lack of exercise
- Smoking
What is the relationship of tobacco and cancer?
Tobacco use is a leading cause of lung cancer and of death from cancer.
*What are the types of cancer tumours? (2 types)
- Malignant (severe)
- Benign (non-severe)
*What are main groups of the types of cancer? (3 main groups)
- Carcinomas
- Sarcomas
- Leukemias, Lymphomas
What is carcinomas?
Malignancy of epithelial cells
What is sarcomas?
Solid tumours of connective tissues, rare in humans
What is leukemias, lymphomas?
Malignancy of blood forming cells and immune cells
What is an example of a tumour suppressor gene?
p53
*The p53 gene is expressed if the DNA is damaged. What is the p53 gene? (2 causes)
- Causes the cell cycle to stop
- Leads to apoptosis
(p53 gene is one of the proteins that regulate the cell cycle)
*What happens if the p53 gene is damaged? (3 causes)
- The cell cycle continues even if the DNA is damaged
- Cells reproduce with damaged DNA
- This can lead to cancer
What is the percentage of human tumours that have abnormal p53 genes?
50% to 55%
What are some actions to protect yourself from cancer and prevent it? (5 examples)
- Reduce your stress
- Improve your diet
- More exercise
- More rest
- Less smoking / No smoking
Is cancer a result of the continued abuse of the body?
Yes
How do we improve our diet? (6 examples)
- Less fatty foods
- Less preserved foods
- Less foods cooked in reused oils
- Less starchy foods cooked at high temperatures
- More fruit, green tea, vitamins
- More fibre
What are some important genes to remember? (3 examples)
- p53
- Bcl-2
- Bax
*What is metastasis?
Spreading of cancer to other cells and other tissues
Some definitions for understanding
(Apoptosis, Oncogene and Tumour suppressor gene)
- Apoptosis: A normal series of events in a cell that leads to its death (and then replacement). Cancer cells avoid apoptosis. Cell development is dependent on the expression of pro and anti apoptotic genes
- Oncogene: A mutated proto-oncogene which causes uncontrolled growth of cells leading to cancer
- Tumour suppressor gene: A gene that produces proteins that suppress uncontrolled growth of cells. Mutation of tumour suppressor genes leads to cancer
