Prokaryotic Transcription Video: Quiz and Flashcards

Study Notes

In this video, the topic is DNA transcription.
Transcription is the process of converting DNA into RNA.
Two types of cells exist: prokaryotic (bacteria) and eukaryotic (complex organisms).
Prokaryotic cells use a single enzyme called RNA polymerase holoenzyme for transcription.
RNA polymerase holoenzyme is made up of two parts: the core enzyme and the sigma subunit.
The core enzyme consists of alpha, beta, beta prime, and omega subunits.
The core enzyme reads the DNA and makes RNA.
The sigma subunit binds to the promoter region of the DNA, allowing the RNA polymerase to transcribe the DNA.
Eukaryotic cells require a different approach for transcription.
They use two different enzymes: RNA polymerase and a transcription factor.
General transcription factors bind to the promoter region, enabling the RNA polymerase to bind and transcribe the DNA.
RNA polymerase 1 creates RRNA, which is incorporated into ribosomes.
RNA polymerase 2 creates mRNA, which undergoes specific modifications before being translated into proteins.
RNA polymerase 3 creates tRNA and a small amount of snRNA, which are involved in splicing.- The text discusses the process of transcription in both prokaryotic and eukaryotic cells, focusing on the role of RNA polymerase and transcription factors.
The text introduces the concepts of RNA polymerase 1, 2, and 3, which respectively produce messenger RNA (mRNA), ribosomal RNA (rrRNA), and transfer RNA (tRNA).
In eukaryotic cells, particular transcription factors are needed for each RNA polymerase to bind to the promoter region and initiate transcription.
Eukaryotic cells have two ways of modulating the rate of transcription: enhancers increase the transcription rate, while silencers decrease it.
Enhancers are DNA sequences that can increase the transcription rate by causing a looping of the DNA and bringing the promoter region into close proximity.
Specific transcription factors bind to enhancers and cause the DNA to loop, allowing the general transcription factors and RNA polymerase to stimulate transcription.
Silencers work in a similar way, but they inhibit transcription by bringing the silencer region into close proximity with the promoter region and inhibiting the promoter.
The text explains how hormones can increase the transcription rate of specific genes in eukaryotic cells through a signaling cascade that activates specific transcription factors.
Initiation of transcription in both prokaryotic and eukaryotic cells involves binding of RNA polymerase to the promoter region, which is a specific sequence of nucleotides that allows binding.
Prokaryotic cells have a single RNA polymerase holoenzyme, while eukaryotic cells have RNA polymerase type 2, which specifically binds to the promoter region of mRNA genes.
The initiation of transcription requires not only the RNA polymerase, but also general transcription factors, which help the RNA polymerase bind to the promoter region and initiate transcription.
The text mentions several specific transcription factors, including transcription factor 2d, which contains a tata binding protein that binds to the TATA box in the promoter region.- Two types of RNA polymerases: rna polymerase I (prokaryotic) and rna polymerase II (eukaryotic)
rna polymerase II binds to the DNA at the promoter region containing the tata box
Transcription factor 2D contains the tata binding protein which helps rna polymerase II bind to the DNA
Once rna polymerase II binds to the DNA, it starts moving down the DNA strands and making RNA (transcription)
RNA is made in the opposite direction of the DNA (elongation)
Both strands of the DNA are involved: the template strand (antisense) and the coding strand (sense)
rna polymerase reads the template strand and synthesizes RNA using the complementary base of the nucleotides
rna polymerase uses its intrinsic helicase activity to unwind the DNA during the transcription process
Elongation process continues until the termination sequence is reached
rna polymerase falls off the DNA once it reaches the termination sequence
In eukaryotic cells, the RNA made during transcription is called heterogeneous nuclear RNA (hnRNA)
hnRNA undergoes post-transcriptional modification to become mature mRNA
Five prime end of the hnRNA is capped with a 7-methylguanosine group to help initiate translation and prevent degradation
Three prime end of the hnRNA is polyadenylated with a poly(A) tail to help initiate translation and prevent degradation
Poly A polymerase adds adenine nucleotides to the three prime end of the RNA
Splicing removes introns and joins exons together to form a mature mRNA.

Description

Explore the process of transcription in prokaryotic and eukaryotic cells, highlighting the roles of RNA polymerase, transcription factors, and specific enzymes. Understand the nuances of initiation, elongation, and termination in DNA transcription, as well as the post-transcriptional modifications involved in creating mature mRNA.