18 Flashcards
Germline mutation
If a mutation occurs in a cell that go on to make gametes (egg or sperm cells), the mutation can be passed on to the next generation ( e.g. in born errors of metabolism).
Somatic mutation
Somatic mutation - occur in other cells and cannot be passed on – can result in caner.
Somatic vs Germaine mutation
How many cells is the human body made from
37 trillion
Cell growth and cell death in cells - balance
- Normally, human cells grow and divide to form new cells as the body needs them.
- When cells grow old or become damaged, they die, and new cells take their place.
What is cancer?
Cancer is a collection of related diseases and can start almost anywhere in the body.
What are cancers cells? Do they respond to signals?
Cancer cells are cells within a tissue that longer respond to many of the signals that control cellular growth and death. Over time, these cells become increasingly resistant to the controls that maintain normal tissue — and as a result, they divide more rapidly.
Do cancer cells do programmed death?
No
What happens in the late stages of cancer
In the late stages of cancer, cells break through normal tissue boundaries and metastasize (spread) to new sites in the body
What underlies the development of cancer?
Multiple mutation
Cancer is the result of….
An accumulation of mutations
What are most mutations associated with?
DNA replication
The more times a cell decides, the more likely it is to…..
Gain a mutation
Why does incidence of cancer increase greatly with age
The more times a cell divides, the more likely it to gain a mutation
• Hundreds of _______ encode _____ that normally regulate cell
_____ and _______
• _________ that alter these genes in ______ cells can lead to
________
• Hundreds of genes encode proteins that normally regulate cell growth and division
• Mutations that alter these genes in somatic cells can lead to cancer
Mutations may be _____ or result of ______
Mutations may be spontaneous (occur by chance) or the result of exposure to a mutagen (also called carcinogen)
Two types of genes cause cancer when mutated
Tumor supressor genes
Once-genes
What do tumor suppressor genes fo?
E ncode proteins that normally prevent uncontrolled cell growth e.g.;
• proteins that inhibit cell division
• Prevent other mutations (DNA repair enzymes)
What does the lack of tumor suppressor gees do
Lack of these genes can stimulate cell growth - i.e. recessive mutations promote cancer
What do oncogenes result form
Mutations that increase gene activity
Example of hoe oncogene and tumor supressor mutations lead to cancer
Chronic myeloid leukemia
What are once-genes
Encode proteins that promote cell growth
e.g: Proteins that stimulate cell division
Cancer mutations increase the activity of
these genes
Dominant mutations promote cancer
Can this cell under go cell division? Why? (Tumor suppressor genes - mutations that decrease gene activity cause cancer)
The cell is prevented from undergoing cell division due to inactivation of E2F transcription factor
Can this cell undergo cell division ? Why?
Yes
Signal for cell division results in E2F transcription factor moving in to the nucleus
Cell divison genes can then be expressed
What else prevents the E2F being activated? What does it do to the kinase?
P16 binds to kinase preventing it from phosphorylating the RB protein at the wrong time
What are the multiple checks that prevent replication happening
- p16 on the kinase
- transcription factor E2F controlled by RB proven
What happens here?
Loss of function mutation in RB gene cause activation of the E2F transcription factor
MUST HAVE MUTATION IN BOTH COPIES as recessive
What’s happening here?
Loss of function mutation in p16 gene cause activation of the E2F transcription factor
Lots of genes important for controlling when and where cells divide
Yes
What is a proto-oncogene
A normal gene that when mutated can promote uncontrolled cell growth
Cancer treatments
Surgery: remove cancer cells
Radiation therapy: targeted radiation to kill cancer cells
Chemotherapy: uses dugs that target dividing cells as cancer cells grow rapidly - but also affects normal cells
Targeted therapy ;
- drugs that target changes in cancer cells that allow them to grow and divide
- BCR-ABL translocation - not present in any other cells apart from cancer cells
- gleevac inhibits kinase activity of BCR-ABL
