------------------control(s) which genes are expressed and at what times.
is it transcription factors?
or am I wrong?
Transcription of the DNA is the first step. Yes, this is the beginning.
You are correct that transcription factors play a crucial role in controlling gene expression. Transcription factors are proteins that bind to specific DNA sequences, called promoter regions, and regulate the initiation of transcription. By binding to these promoter regions, transcription factors can either activate or repress gene expression. They can recruit or block RNA polymerase, the enzyme responsible for synthesizing RNA from DNA, thereby controlling when and how efficiently transcription occurs.
Additionally, there are other factors involved in gene expression regulation, such as chromatin remodeling proteins, enhancers, and repressors. Chromatin remodeling proteins modify the structure of the chromatin, which is the complex of DNA and histone proteins, either making the genes more accessible or less accessible to transcription machinery. Enhancers are DNA sequences that can enhance transcription by interacting with specific transcription factors. Repressors, on the other hand, inhibit gene expression by blocking the activity of transcription factors or other components of the transcription machinery.
So, while transcription factors are indeed a key player in controlling gene expression, they are part of a larger network of regulatory elements that work together to determine which genes are expressed and when.