Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

5BBG0205 Molecular Basis of Gene Expression > L2: Transcription & processing of eukaryotic genes > Flashcards

L2: Transcription & processing of eukaryotic genes Flashcards

1
Q

What are the main components of a transcription initiation complex in eukaryotes?

A
  • RNA polymerase II
  • promoters
  • general transcription factors (GTFs)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

In eukaryotes, what is the order in which transcription is initiated?

A
  • binding of RNA polymerase II to the promoter region of the gene
  • followed by recruitment of GTFs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Explain the mechanisms of processing eukaryotic mRNA during transcription initiation

A

-RNA polymerase II binds to the promoter region
- GTFs facilitate the assembly of the transcription initiation complex, leading to the start of mRNA synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the mechanisms involved in termination and polyadenylation during eukaryotic mRNA processing?

A
  • recognition of specific termination sequences
  • then the addition of a poly-A tail at the 3’ end of the mRNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Provide examples of gene expression regulation at different stages of RNA processing

A
  • Gene expression can be regulated during transcription initiation by the binding of TFs to enhancer regions.
  • Polyadenylation can be regulated by factors that influence the cleavage and addition of the poly-A tail.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the central dogma of molecular biology?

A
  • states the unidirectional flow of genetic information: DNA (genes) undergo transcription to form RNA, which - then translated into proteins.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the role of DNA transcription and RNA processing in gene expression?

A
  • DNA transcription = process of synthesizing RNA from a DNA template, and RNA processing = involves modifications to the RNA molecule, such as splicing & polyadenylation.
    both play a key role in determining cellular fate and function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does the gene expression pathway determine cellular fate?

A
  • gene expression pathway regulates which genes are transcribed & processed into RNA
  • leads to production of specific proteins that govern cellular functions & determine the fate of the cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the process of eukaryotic transcription?

A

DNA unwinds to expose bases.
One DNA strand acts as a template.
RNA synthesis directed by the template.
Forms an initiation complex with RNA pol II and promoter.
Transcription factors assist in complex formation.
RNA elongated one nucleotide at a time.
RNA transcribed in the nucleus.
RNA is complementary to template DNA strand.
Uracil (U) replaces thymine (T) in RNA.
RNA helix reforms behind transcription.
RNA released as a single strand.
RNA is a messenger and information carrier.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the main types of RNA in eukaryotic cells and their functions?

A

Messenger RNA (mRNA): Codes for proteins (3% total RNA).
Ribosomal RNA (rRNA): Forms ribosome structure, catalyzes protein synthesis (71% total RNA).
Transfer RNA (tRNA): Acts as adaptors between mRNA and amino acids (15% total RNA).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How can each type of RNA be characterized?

A
  • by size and sedimentation behavior (Svedberg’s coefficient, S).
  • Sedimentation behavior influenced by density, mass, and shape
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the significance of mRNA in a cell?

A

mRNA is a small percentage of total RNA.
Codes for all functional proteins in the cell.
mRNA is the only coding type of RNA.
DNA → Transcription → mRNA → Translation → Protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is DNA transcribed into different types of RNA?

A

DNA transcribed into mRNA (coding RNA) or non-coding RNA.
rRNA, tRNA, etc. are non-coding types of RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the transcription initiation complex and how is it formed?

A
  • complex forms upstream of a gene on DNA.
  • Interaction between genomic DNA promoters and General Transcription Factors (GTFs) and RNA pol II.
  • GTFs needed for transcription initiation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are promoters and their role in transcription?

A
  • Short sequences upstream of the coding region.
  • RNA pol binds to promoters.
    Example: TATA box, conserved sequence 25-35bp upstream.
  • TATA box positions RNA pol II for proper initiation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the TATA box and its significance?

A
  • Conserved promoter sequence (TATAAA/TATAAG).
  • Positions RNA polymerase II through GTFs.
  • Identified by analyzing base frequency in aligned eukaryotic genes
17
Q

Why can’t RNA pol II directly bind to DNA?

A
  • RNA pol II needs GTFs to bind first.
  • GTFs help in positioning RNA pol II at the promoter
18
Q

What are GTFs?

A
  • Required for RNA pol II transcription initiation.
  • Multimeric and conserved proteins.
  • Binding follows an ordered manner.
  • Position RNA pol II at the promoter.
  • Complex process involving hundreds of proteins.
19
Q

How are DNA-protein interactions involved in transcription initiation?

A
  • DNA-protein interactions form the pol II transcription initiation complex.
  • Short DNA sequences (e.g., TATA box) interact with proteins (GTFs).
  • GTFs are required for assembly of the transcription initiation complex
20
Q

What is the step-wise assembly of the transcription initiation complex?

A
  1. TATA-binding protein (TBP) binds TATA-box.
  2. TFIIB binds to the TBP complex.
  3. TFIIB acts as a bridge for RNA pol II recruitment.
  4. RNA pol II, TFIIE, and TFIIH associate to form preinitiation complex.
  5. TFIIH unwinds DNA using ATP hydrolysis and phosphorylation.
  6. RNA pol II leaves promoter, starts elongation of nascent RNA
21
Q

How is pre-mRNA processed and what is its significance?

A
  • Entire gene, including introns and exons, is copied into pre-mRNA.
  • Pre-mRNA processing involves capping, polyadenylation, and splicing.
  • Mature mRNA lacks introns, has a 5’ cap, protein coding region, 3’ UTR, and poly-A tail
22
Q

What is the process of 3’ end cleavage and polyadenylation of mRNA?

A
  • Cleavage and addition of poly A tail to 3’ end during RNA processing.
  • Polyadenylation stabilizes RNA, enhances nuclear export, aids in translation.
  • Assembly of complex involves CPSF, CStF, CFI, CFII, and PAP
23
Q

How does the assembly of the cleavage/polyadenylation complex resemble transcription initiation?

A
  • Both involve multi-protein complexes forming through interactions.
  • Assembly cooperatively occurs through protein-nucleic acid and protein-protein interactions
24
Q

What are the key steps in the cleavage/polyadenylation complex assembly?

A
  • CPSF binds to AU-rich PolyA signal.
  • CStF, CFI, CFII proteins bind, causing pre-mRNA bending.
  • PAP cleaves 10-35 nucleotides upstream of G/U-rich PolyA signal.
  • Free 3’ end is polyadenylated by PAP (slow polyadenylation)
25
Q

How does rapid polyadenylation occur in the cleavage/polyadenylation complex?

A
  • PABII binds to short A tail.
  • Accelerates A addition by PAP (rapid polyadenylation).
  • PABII signals PAP to stop polymerization after 200-250 residues
26
Q

What is the basis of transcription initiation and polyadenylation?

A
  • transcription initiation = involves DNA sequences binding to General Transcription Factors (GTFs).
  • Polyadenylation = involves conserved sequences in pre-mRNA binding to proteins
27
Q

How do interactions differ in RNA processing and transcription initiation?

A
  • RNA processing = involves interactions between RNA sequences & proteins.
  • Transcription initiation = involves interactions between DNA sequences & proteins
28
Q

Why is gene expression carefully regulated in cells?

A
  • Gene expression controlled to ensure only necessary genes expressed
  • Proteins produced in varying amounts based on cell’s needs
  • Correct gene expression allows cells to perform specialized functions
29
Q

How does gene expression regulation occur?

A
  • Gene expression regulated in response to cell’s function & needs.
  • Key regulatory stages include differentiation, development, and environmental responses
30
Q

What are key stages of gene regulation and their examples?

A
  • Occurs during differentiation, development, and environmental responses.
  • Example: Cyclins needed for cell division expressed at specific cell cycle stages
31
Q

How can problems in gene expression lead to diseases?

A
  • Cancer: Absence of transcription off switch leads to improper gene expression and cell division.
  • Developmental diseases: Mistakes in protein synthesis can result in organ developmental problems.
  • Chronic diseases like obesity: Abnormal gene expression due to incorrect signals
32
Q

How is transcription initiation regulated in eukaryotic gene expression?

A
  • Transcription initiation controlled by interactions between DNA sequences & regulatory proteins
  • Regulatory proteins (trans) have DNA binding & transcription activation domains.
  • Regulatory sequences (cis) are short DNA sequences influencing transcription
33
Q

What are the types of gene transcription and their characteristics?

A
  • Constitutive genes: Constantly expressed (house-keeping genes).
  • Regulated genes: Selectively expressed based on conditions or cell types
34
Q

How do different types of transcription factors function?

A
  • Two groups of TFs: general and sequence-specific.
  • Proximal promoters and TATA box play roles in transcription initiation
35
Q

How are regulated genes controlled?

A
  • 5’ end of regulated genes contains regulatory cis sequences and promoters.
  • Enhancers, promoters, & specific TFs control gene expression.
  • Combination of protein factors in TIC regulates gene expression
36
Q

How does hormone regulation affect gene expression?

A
  • Hormones from endocrine system switch genes on/off.
  • Hormones bind to receptors, initiate signaling cascades.
  • Hormones stimulate synthesis of proteins in target tissues
37
Q

How can hormones affect gene expression?

A
  • Hormones can bind to cell membrane receptors, starting signaling cascade.
  • Some hormones enter cells, interact with DNA, stimulate transcription.
  • Hormones regulate and coordinate changes in gene expression.
38
Q

How can mRNA processing be regulated?

A
  • U1A protein’s regulation involves inhibition of its pre-mRNA polyadenylation.
  • U1A protein binds to its pre-mRNA, inhibits polyadenylation.
  • Binding prevents mRNA processing, and mRNA doesn’t mature
39
Q
A

5BBG0205 Molecular Basis of Gene Expression (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions