BIOL122 Lecture Notes - Lecture 10: Bone Marrow Suppression, Oncogene, T Cell
Cancer Pathophysiology
Cancer: at risk groups
• Elderly people
• Smokers
• Those with family history
• Obese individuals
• Those with high exposure to carcinogens
- Ultraviolet radiation
- Lionising radiation
- Virus and bacteria
Normal cell cycle regulation:
• Mitosis (cell division) adds/ replaces removes cells
• Apoptosis (programmed cell death) removes cells
• Mitosis= apoptosis
• Both controlled by genes
• Disrupt balance: cancer
Aetiology of cancer:
• Cell cycle consist of interphase and mitosis in labile cells
• Interphase: G1 phase, S phase, G2 phase
• Mitosis: Prophase, metaphase, anaphase and telophase
• Gene check posts and controls during G1 phase, S phase, G2 phase and stages of
mitosis
• Loss of genetic control= root cause of cancer
• Caused by gene mutations that increase cell division and stop differentiation
• Permanent cells are differentiated for specific function; so switch off genes for cell
cycle.
What are mutations:
• Changes in genes @DNA replication or cell division
• Gene change in nucleotide base sequence
• OR chromosome change during meiosis
• Both change phenotype by change in protein synthesis
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Sporadic/ inherited/ familial cancers
• Sporadic: when something triggers new mutations in an individual
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- Mutated gene only in the affected cells. Usually somatic
• Inherited: inherit a mutation
- All body cells have mutation
- Something else triggers mutation in somatic cells: tumour
• Familial: mixture of genetic and environmental factors
Genetic basis of cancer:
• Cancer is caused by two important types of genetic mutations of
- Overactivity of proto- oncogenes
- Inactivity of tumour suppressor genes
• Virus infections can form oncogenes.
- Hepatitis B and C virus
- Epstein- Barr virus
- HPV
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