1: Etoposide is a common chemotherapeutic agent for cancer treatment. Its mode of action involves binding to the double strand breaks caused by Topoisomerase II/DNA Gyrase-like enzymes ahead of the replication fork and preventing their re-ligation. Considering your knowledge on DNA replication and DNA damage, describe some possible effects etoposide can have on DNA replication and cell viability.
1: Etoposide is a common chemotherapeutic agent for cancer treatment. Its mode of action involves binding to the double strand breaks caused by Topoisomerase II/DNA Gyrase-like enzymes ahead of the replication fork and preventing their re-ligation. Considering your knowledge on
![### Replication in Eukaryotes and Protein Functions
**Replication in eukaryotes begins at the OriC sequence. This particular sequence is characterized by:**
- [ ] A-T rich and therefore energetically more favorable to locally unwind DNA.
- [ ] Contains the DnaA boxes.
- [ ] Recruits histone acetyltransferases.
- [ ] Is locally unwound by DnaA, HU and IHF proteins.
---
**QUESTION 16**
**The Single Strand-binding proteins (SSBs) in prokaryotes and the Replication Protein A (RPA) in eukaryotes are functionally equivalent. Their role in the DNA replication process is to (select the correct statement):**
- ( ) Stabilize the single stranded DNA structure after unwinding by the DNA helicase.
- ( ) Recruit the general transcription factors to the promoter.
- ( ) Relieve the torsional stress ahead of the replication fork.
- ( ) Induce double strand breaks.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F07d8cfa3-4982-494b-b978-2201270524fa%2F29fafb4d-804c-4192-898c-d4a31e6a750e%2F8vwxdps_processed.png&w=3840&q=75)
During DNA replication the double helical structure of DNA unwinds by using the enzyme helicase. DNA polymerase, proceeds on the template strand creating a a replication fork or replication bubble. While unwinding the helical strand it creates a tension on the strand ahead of the replication bubble. This is called positive supercoiling which creates tension on the DNA strand and the strand might break. To prevent this cells have DNA topoisomerase II/DNA gyrase enzymes which binds with DNA and relaxes the positive supercoiling and introduces negative supercoiling in an ATP dependent manner.After relaxing the tension it rejoins the double stranded DNA and replication proceeds normally .
Step by step
Solved in 3 steps
