Most chromosomal replicons do not have a termination region like that of bacteria at which the replication forks cease movement and (presumably) dissociate from the DNA. 

TLS Online TPP Program

#Id: 3211

#Unit 4. Cell Communication and Cell Signaling

Three mechanisms can produce oncogenes from the corresponding proto-oncogenes:
Point mutation
Chromosomal translocation
Amplification

TLS Online TPP Program

#Id: 3212

#Unit 4. Cell Communication and Cell Signaling

Point mutation (i.e., a change in a single base pair) in a proto-oncogene that results in a hyperactive or constitutively active protein product.

TLS Online TPP Program

#Id: 3213

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 3214

#Unit 4. Cell Communication and Cell Signaling

Amplification (i.e., abnormal DNA replication) of a DNA segment including a proto-oncogene, leading to overproduction of the encoded protein.

TLS Online TPP Program

#Id: 3216

#Unit 4. Cell Communication and Cell Signaling

Carcinogens

1. Environmental DNA-damaging agents

2.Prevent DNA damage from being repaired with high fidelity

TLS Online TPP Program

#Id: 3218

#Unit 4. Cell Communication and Cell Signaling

Chemical carcinogens classified into two general categories:
1. Direct-acting carcinogens
2. Indirect-acting carcinogens