transcription factor

Question 1

importnace of promotor region

Answer 1

the change in shape of the TF allows binding of TF, which binds to the promotor region. controlling expression of gene. binding of TF my activate or repress gene (turn on or off).

Question 2

DNA methylation

Answer 2

addition of a methyl group to the cytosine base of DNA. Blocks transcription → gene gets turned OFF.

Methylation makes the DNA structure more compact.

This stops RNA polymerase and transcription factors from binding.

Question 3

transcription factors

Answer 3

What are they?
Proteins that bind to specific DNA sequences (like promoters or enhancers) to turn genes ON or OFF.

🔹 What do they do?
They recruit RNA polymerase to start transcription, or they block it.

🔹 How?
Activator transcription factors → increase transcription

Repressor transcription factors → decrease transcription

🔹 Is it permanent?
Not permanent

Question 4

🔄 Summary:
Once the blastocyst forms, totipotent cells have differentiated.

The inner cell mass cells are now pluripotent, not totipotent anymore.

So totipotency only lasts for the first few divisions after fertilization (up to around the 8-cell stage).