Podcast
Questions and Answers
In eukaryotes, gene control's primary role in multicellular organisms is to execute precise developmental and tissue-specific programs, ensuring:
In eukaryotes, gene control's primary role in multicellular organisms is to execute precise developmental and tissue-specific programs, ensuring:
- only essential genes are expressed, regardless of cell type.
- gene expression is uniform across all cell types and developmental stages.
- the proper genes are expressed in the proper cells at the proper times. (correct)
- genes are expressed randomly throughout development.
Transcription in eukaryotes occurs on naked DNA, similar to prokaryotes.
Transcription in eukaryotes occurs on naked DNA, similar to prokaryotes.
False (B)
What is the term for the regulation of gene expression mediated by chromatin?
What is the term for the regulation of gene expression mediated by chromatin?
Epigenetic Regulation
Regions of chromosomes that are intensely stained and contain inactive genes are called ______.
Regions of chromosomes that are intensely stained and contain inactive genes are called ______.
Match the following chromatin states with their transcriptional activity:
Match the following chromatin states with their transcriptional activity:
Which of the following statements best describes the complexity of eukaryotic transcriptional control compared to prokaryotic control?
Which of the following statements best describes the complexity of eukaryotic transcriptional control compared to prokaryotic control?
Eukaryotes possess a single type of RNA polymerase responsible for transcribing all classes of RNA.
Eukaryotes possess a single type of RNA polymerase responsible for transcribing all classes of RNA.
Which RNA polymerase synthesizes only pre-rRNA in eukaryotes?
Which RNA polymerase synthesizes only pre-rRNA in eukaryotes?
RNA polymerase II synthesizes mRNAs and also some of the small nuclear RNAs that participate in mRNA ______ and micro- and small interfering RNAs.
RNA polymerase II synthesizes mRNAs and also some of the small nuclear RNAs that participate in mRNA ______ and micro- and small interfering RNAs.
Match each eukaryotic RNA polymerase with its primary RNA product:
Match each eukaryotic RNA polymerase with its primary RNA product:
Eukaryotic RNA polymerases share a high level of homology with which of the following?
Eukaryotic RNA polymerases share a high level of homology with which of the following?
The structures of eukaryotic RNA polymerases have no similarity to prokaryotic RNA polymerases.
The structures of eukaryotic RNA polymerases have no similarity to prokaryotic RNA polymerases.
What structural feature in eukaryotic RNA polymerases accommodates DNA and is closed after positioning over the DNA?
What structural feature in eukaryotic RNA polymerases accommodates DNA and is closed after positioning over the DNA?
The synthesis of RNA by RNA polymerases takes place in the ______ with the participation of Mg++.
The synthesis of RNA by RNA polymerases takes place in the ______ with the participation of Mg++.
Relate the features to what it refers to in RNA Polymerases:
Relate the features to what it refers to in RNA Polymerases:
What is the function of phosphorylation of the Ser residues found in the CTD of RNA polymerase II during transcription?
What is the function of phosphorylation of the Ser residues found in the CTD of RNA polymerase II during transcription?
The CTD of eukaryotic RNA polymerase II is a highly structured domain that can be easily analyzed by crystallography.
The CTD of eukaryotic RNA polymerase II is a highly structured domain that can be easily analyzed by crystallography.
What sequence is repeated multiple times in the CTD of RNA polymerase II in yeast?
What sequence is repeated multiple times in the CTD of RNA polymerase II in yeast?
Genes transcribed by RNA polymerase II are regulated by core promoter sequences and promoter-proximal binding sites for transcriptional ______.
Genes transcribed by RNA polymerase II are regulated by core promoter sequences and promoter-proximal binding sites for transcriptional ______.
Match the core promoter elements with descriptions:
Match the core promoter elements with descriptions:
Transcription starts at a defined point on the DNA called the:
Transcription starts at a defined point on the DNA called the:
RNA polymerases can recognize and correctly initiate transcription at a promoter without the assistance of other factors.
RNA polymerases can recognize and correctly initiate transcription at a promoter without the assistance of other factors.
What general factors assemble the preinitiation complex over the core promoter sequences?
What general factors assemble the preinitiation complex over the core promoter sequences?
RNA polymerase II GTFs are labeled as ______.
RNA polymerase II GTFs are labeled as ______.
Which list contains correct components labeled as TFII?
Which list contains correct components labeled as TFII?
Flashcards
Eukaryotic Transcription
Eukaryotic Transcription
Transcription in eukaryotes occurs on DNA wrapped in chromatin, requiring chromatin to open for gene activation.
Heterochromatin
Heterochromatin
Regions of chromosomes that are intensely stained and contain DNA that is more densely packed.
Euchromatin
Euchromatin
Regions of chromosomes that are lightly stained and contain active genes.
RNA polymerase I function
RNA polymerase I function
Signup and view all the flashcards
RNA polymerase II function
RNA polymerase II function
Signup and view all the flashcards
RNA polymerase III function
RNA polymerase III function
Signup and view all the flashcards
Clamp Domain
Clamp Domain
Signup and view all the flashcards
CTD of RNA Polymerase II
CTD of RNA Polymerase II
Signup and view all the flashcards
Initiation site
Initiation site
Signup and view all the flashcards
TATA box
TATA box
Signup and view all the flashcards
BRE and DPE
BRE and DPE
Signup and view all the flashcards
General Transcription Factors (GTFs)
General Transcription Factors (GTFs)
Signup and view all the flashcards
Study Notes
Overview of Eukaryotic Gene Control
- Multicellular organisms use gene control to execute developmental and tissue-specific programs
- This ensures the correct genes are expressed in the correct cells at the correct times during embryonic development and cellular differentiation
Chromatin and Gene Regulation
- Transcription in eukaryotes occurs on DNA wrapped in chromatin
- Chromatin must open for gene activation and transcription
- Chromatin-mediated regulation is a mechanism compared to prokaryotes
- This is also known as Epigenetic regulation of gene expression.
Heterochromatin vs. Euchromatin
- Heterochromatin is densely packed DNA.
- Euchromatin is less packed DNA.
- Heterochromatin: 'hetero' means different.
- Euchromatin: 'eu' means true.
Heterochromatin Characteristics
- Regions of chromosomes that are intensely stained.
- DNA is more densely packed.
- Mostly repetitive DNA (transposons, centromeres, and telomeres).
- Not easily accessible to transcriptional machinery.
- Inactive genes are often within heterochromatin regions.
Euchromatin Characteristics
- Lightly stained chromosome regions.
- Active genes are found in euchromatin.
- Highly accessible to transcriptional machinery.
Transcription Complexity in Eukaryotes
- Gene expression is regulated by a system with many factors once the gene is in open chromatin
- This system is more complicated than in prokaryotes
RNA Polymerases in Eukaryotes
- Eukaryotes have three RNA polymerases: RNA polymerase I, II, and III
- RNA polymerase I synthesizes pre-rRNA
- RNA Polymerase II synthesizes mRNAs and some small nuclear RNAs
- Some small nuclear RNAs (miRNAs and siRNAs) regulate the translation and stability of mRNAs
- RNA polymerase III synthesizes tRNAs, 5S rRNA, and other small stable RNAs
RNA Polymerase Structure and Function
- All eukaryotic RNA polymerases share high homology with yeast RNA polymerase II.
- Yeast RNA polymerase structure has been resolved at high resolution.
- RNA polymerase II has twelve polypeptides known as RPB1, RPB2...RPB12.
- RNA polymerase's clamp domain (RPB1) needs to accommodate DNA.
- After the RNA polymerase finds & binds to the DNA, the clamp closes by a bridge
- RNA synthesis occurs at the catalytic center, utilizing Mg++
Eukaryotic RNA Polymerase II and CTD
- Eukaryotic RNA polymerase II has a Carboxyl-Terminal Domain (CTD) on its RPB1 subunit
- The CTD domain is specific to RNA polymerase II.
- It is a highly specialized region involved in regulation during initiation, release, elongation and processing of synthesized mRNAs.
- The CTD of yeast contains repeats of Tyr-Ser-Pro-Thr-Ser-Pro-Ser.
- These series contains 26 repeats in yeast, and 52 in mammals
- The Ser residues within the CTD are phosphorylated during the transition process from initiation of elongation
RNA Polymerase II Promoters and Transcription Factors
- RNA polymerase II transcribed genes are regulated by: conserved basal promoter elements, promoter-proximal binding sites transcriptional activators and distal enhancers or repressors
- The process is influenced by the chromatin structure of the gene
- Conserved basal promoter elements are also known as CORE promoter sequences
- The 4 elements direct positioning of polymerase at the promoters: TATA Box, Initiator, BRE a TFIIB recognition element and DPE a downstream promoter element
Core Promoter Elements In Detail
- Transcription starts at the initiation site
- An Adenine base is usually found on the coding strand
- TATA box: a tight consensus sequence (prevalent in highly transcribed genes)
- Initiator: less conserved element (some genes contain this but no TATA)
- BRE (TFIIIB Recognition Element): influences the activity of the promoter
- DPE (Downstream Promoter Element): influences the activity of the promoter
General Transcription Factors
- RNA polymerases will locate a promoter & correctly initiate transcription at that site.
- Doing this is impossible by themselves.
- General Pol II Transcription Factors (GTFs) help make it possible.
- GTFs assemble the preinitiation complex over the CORE promoter sequences.
- Other factors, such as DNA Helicase, help the polymerase initiate transcription. Other factors (protein kinase) release the polymerase, others elongate the polymerase and move nucleosomes
GTF Labels
- RNA pol I GTFs are labeled as TFI
- For example: TFIA and TFIB
- RNA pol II GTFs are labeled as TFII
- For example: TFIIA, TFIIB, TFIID, TFIIE, and TFIIH
- RNA pol III GTFs are labeled as TFIII
- For example: TFIIIB and TFIIIS
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
