Midterm 2 - Notes 4 (Part 1) Flashcards
Why study plant tumours on the molecular level? (3)
- Understanding the mechanisms underlying cellular differentiation
- Best studied example of inter-kingdom lateral gene transfer
- Led to the primary tool for generating genetically modified plants
What are tumours defined by?
Their phenotype
- not how they originate
Phenotype
The set of observable characteristics of an individual resulting from the interaction of its genotype with the environment
Tumour
An abnormal mass of tissue that results from excessive cell division or reduced cell death
- can be benign or malignant
Benign
No invasion to nearby tissue or spreading to other parts of the body
- will not invade into nearby tissues and cause harm
Malignant
Tendency to invade and destroy nearby tissue and/or spread to other parts of the body (forms metastases)
- can break off and establish itself somewhere else in the body and spread from there
Merkel cell tumour
Is a rare malignant tumours of the skin in humans
Crown gall tumour
A common tumour of stems and roots on an elm tree
How do cancer cells reproduce?
Without any restraints on cell growth, cell division or apoptosis
Apoptosis
Programmed cell death
How do cancers evolve?
Gradually
What do tumours contain? (2)
- Increase number of somatic mutations
2 Epigenetic alterations
What does the cause of malfunctioning of regulatory proteins lead to? (2)
- Increase in cell division
2. Decrease in cell death
What are 4 key roles that mutated genes play in?
- DNA repair
- Cell signalling
- Cell growth and differentiation
- Cell cycle count
With check point is environmentally favoured?
G1 to S checkpoint
Which check point is all DNA replicated and is environmentally favoured?
G2 to M checkpoint
What do mutated genes play a role in? (2)
- Cell division
2. Apoptosis
What do mutated genes help regulate?
The cell cycle
At what speed do tumours progress?
Slowly
What can increase the chance of getting cancer?
Exposure to mutagen/ carcinogen
Can single exposure cause cancer?
No
- needs to be over a long period of time to constant exposure
What are the 4 stages in tumour progression?
- Normal tissue
- Mild disorder
- Benign tumour
- Malignant cancer
What increases the chance of getting mutations?
Genetic instability
What do pre-cancerous cells do compared to normal cells?
Accumulate more mutations
What 3 things may initial mutations interfere with?
- DNA repair
- DNA damage response
- Epigenetic control mechanisms
What are critical cancer genes necessary to?
Withstand homeostasis
What do additional mutations required can cause the cell to do? (3)
- Constitutively activate cell division in absence of growth factors
- Become insensitive to external and internal signals
- Induce help from normal tissues
What are 4 examples of external and internal signals?
- Anti-proliferating factors
- Apoptosis inducing factors
- Factors inducing differentiation
- Factors preventing proliferation without adhesion
What can subsequent mutations become?
Invasive
Oncogene
Cancer causing gene
- only when mutated
What is an example of a GOF gene?
Oncogene
- dominant
- over activation/over expression
What is an example of LOF gene?
Tumor supressor genes
- recessive
- under activate/ missing
