B2.1 How do cancers grow ? Flashcards
What is the hayflick limit ?
Most cells can divide 20-60 times before becoming senescence
What is the meaning of senescence ?
Cellular old age, can no longer divide
What are telomeres ?
Repetitive regions on the end of chromosomes
What happens to telomeres when cells divide each time ?
They get shorter
What can restore telomeres from getting short ?
Telomerase and enzyme
Where are telomerase normally expressed ?
Germ cells and stem cells
True or false.
90% of malignant cells express telomerase’s in order to help them replicate beyond the hayflick limit
True
Do most healthy cells contain telomerase ?
No
Why do we need telomeres ?
They’re protective , accreting as buffered to prevent the DNA sequence getting shorter
What is the function of RNA primers ?
Tells DNA polymerase where to start with DNA replication
Are RNA promises degraded and if so what gaps are filled in and what gaps are left ?
Yes. They’re degraded. Internal gaps are filled in
Terminal gaps are left
What percentage of cancer cells have an activation of the telomerase enzyme ?
90%
What do the other 10% undergo ?
Alternative telomere lengthening or ALT, where there is recombination or fusion between the ends of different chromosomes
