Session 7 Lecture Notes Flashcards
What genes regulate normal cell proliferation?
Proto-oncogenes
What 4 effects can a chemical signal have on a cell?
- Survive
- Divide - enter the cell cycle
- Differentiate
- Apoptosis
What part of the cell cycle can you see under a light microscope?
Mitosis and cytokinesis (NOT interphase)
Can cells with damaged DNA normally replicate and why?
NO
Because there are checkpoints during the cell cycle that check for mutations etc
2 important checkpoints are end of G1 and end of G2
The most important checkpoint is the R checkpoint
What is the most commonly altered checkpoint in cancer cells?
The R checkpoint (when cells make it past this they are able to replicate - the point of no return)
If a faulty cell activates a checkpoint what protein moves it into apoptosis?
p53
What enzymes and proteins are responsible for regulating the cell cycle?
Cyclin - dependent kinases (enzymes) are activated when bound by certain cyclins (proteins)
What action does CDK do when bound by its correct cyclin?
It phosphorylates its target protein (substrate) by adding a phosphate from ATP to stretches of AAs
How many times can a cell divide if telomerase doesn’t exist?
61.3 times (the telomere shortens each time the cell divides)
What is hyperplasia?
Cells increase in NUMBER which leads to an increase in tissue or organ size
What is hypertrophy?
Cells increase in SIZE which leads to an increase in tissue or organ size
What is atrophy?
Cells becomes SMALLER which leads to the organ or tissue shrinking in size
What is metaplasia?
Cells are replaced by a different cell type
This is because STEM CELLS that produced one line of cells switch to another line (the cell itself DOES NOT switch)
What 2 types of tissue can hyperplasia occur in?
Labile and stabile tissue
Give 2 examples of pathological hyperplasia
- Eczema
2. Goitre (due to iodine deficiency)
In which type of tissue can hypertrophy occur?
Labile, stabile and especially permanent
Give 2 examples of physiological hypertrophy
- Skeletal muscle
2. Pregnant uterus
What is compensatory hypertrophy?
Damage to either:
- one of a pair of organs (eg a kidney)
- damage to part of a single organ
Which causes the remainder to enlarge to compensate
There are many examples of pathological atrophy - name some
- Reduced functional demand/workload (atrophy of disuse)
- Loss of innervation (denervation atrophy)
- Inadequate blood supply
- Inadequate nutrition
- Loss of endocrine stimuli
- Persistent injury eg polymyositis (inflammation of muscle)
- Aging (senile atrophy)
- Pressure eg tissue around an enlarging brain
Give an example of atrophy of extracellular matrix
Osteoporosis (lack of bone substance i.e. losing the bone matrix)
In which cells types does metaplasia usually occur?
Labile or stabile tissue
Does metaplasia predispose to cancer?
Yes it can in some cases
It can be a prelude to dysplasia and cancer
What is aplasia?
Complete failure of an organ or tissue to develop (it is an embryonic developmental disorder)
It can also be used to describe an organ whose cells have ceased to proliferate
What is hypoplasia?
Underdevelopment or incomplete development of tissue or organ at embryonic stage (inadequate cell number)
