Podcast
Questions and Answers
What is the primary function of TERC in relation to telomerase?
What is the primary function of TERC in relation to telomerase?
HOTAIR is an ncRNA that enhances gene expression by modifying histones.
HOTAIR is an ncRNA that enhances gene expression by modifying histones.
False
What does telomerase add to the end of the chromosome, and what is its purpose?
What does telomerase add to the end of the chromosome, and what is its purpose?
Excess DNA, to create room for future primer.
The ncRNA known as ______ regulates transcription by forming a scaffold for protein complexes.
The ncRNA known as ______ regulates transcription by forming a scaffold for protein complexes.
Signup and view all the answers
Match the following terms with their definitions:
Match the following terms with their definitions:
Signup and view all the answers
What percentage of transcription in a typical human cell is associated with making ncRNAs?
What percentage of transcription in a typical human cell is associated with making ncRNAs?
Signup and view all the answers
Non-coding RNAs can only bind to DNA.
Non-coding RNAs can only bind to DNA.
Signup and view all the answers
What is a ribozyme?
What is a ribozyme?
Signup and view all the answers
NcRNAs can affect processes of __________, transcription, and translation.
NcRNAs can affect processes of __________, transcription, and translation.
Signup and view all the answers
Match the following functionalities of ncRNAs with their respective roles:
Match the following functionalities of ncRNAs with their respective roles:
Signup and view all the answers
Which of the following is NOT a function of non-coding RNAs?
Which of the following is NOT a function of non-coding RNAs?
Signup and view all the answers
Only a small portion of ncRNAs have roles in human diseases.
Only a small portion of ncRNAs have roles in human diseases.
Signup and view all the answers
What is the primary difference between coding and non-coding RNAs?
What is the primary difference between coding and non-coding RNAs?
Signup and view all the answers
What is the repeat sequence found in human telomeres?
What is the repeat sequence found in human telomeres?
Signup and view all the answers
As cells divide, telomeres become longer.
As cells divide, telomeres become longer.
Signup and view all the answers
What enzyme is responsible for adding repeating sequences to telomeres?
What enzyme is responsible for adding repeating sequences to telomeres?
Signup and view all the answers
The ends of the chromosomes cannot be fully replicated by __________.
The ends of the chromosomes cannot be fully replicated by __________.
Signup and view all the answers
What happens to a cell when its telomeres become too short?
What happens to a cell when its telomeres become too short?
Signup and view all the answers
What is the function of telomeres?
What is the function of telomeres?
Signup and view all the answers
Telomere lengthening occurs in _______ steps.
Telomere lengthening occurs in _______ steps.
Signup and view all the answers
What is one primary function of the Signal Recognition Particle (SRP)?
What is one primary function of the Signal Recognition Particle (SRP)?
Signup and view all the answers
SRP is composed solely of protein.
SRP is composed solely of protein.
Signup and view all the answers
What must bind GTP for SRP to bind to its receptor in the ER membrane?
What must bind GTP for SRP to bind to its receptor in the ER membrane?
Signup and view all the answers
The SRP changes a protein's function to open a __________ for the polypeptide.
The SRP changes a protein's function to open a __________ for the polypeptide.
Signup and view all the answers
What is the result of GTP hydrolysis in the SRP and SRP receptor complex?
What is the result of GTP hydrolysis in the SRP and SRP receptor complex?
Signup and view all the answers
During translation, SRP pauses the process upon binding to an ER signal __________.
During translation, SRP pauses the process upon binding to an ER signal __________.
Signup and view all the answers
What is the relationship between SRP and non-coding RNA (ncRNA)?
What is the relationship between SRP and non-coding RNA (ncRNA)?
Signup and view all the answers
Match the following components with their roles in the SRP pathway:
Match the following components with their roles in the SRP pathway:
Signup and view all the answers
What is the role of the Cas9 protein in the interference phase?
What is the role of the Cas9 protein in the interference phase?
Signup and view all the answers
NcRNAs have no impact on human diseases.
NcRNAs have no impact on human diseases.
Signup and view all the answers
Name one type of cancer where abnormal expression levels of certain miRNAs have been found.
Name one type of cancer where abnormal expression levels of certain miRNAs have been found.
Signup and view all the answers
HOTAIR behaves as an ______ when overexpressed.
HOTAIR behaves as an ______ when overexpressed.
Signup and view all the answers
Match the following roles of ncRNAs with their applications:
Match the following roles of ncRNAs with their applications:
Signup and view all the answers
What is the primary function of the CRISPR-Cas system in bacteria?
What is the primary function of the CRISPR-Cas system in bacteria?
Signup and view all the answers
The type II CRISPR-Cas system contains multiple types of CRISPR-associated genes.
The type II CRISPR-Cas system contains multiple types of CRISPR-associated genes.
Signup and view all the answers
What proteins form a complex to recognize and cleave foreign bacteriophage DNA during the adaptation phase?
What proteins form a complex to recognize and cleave foreign bacteriophage DNA during the adaptation phase?
Signup and view all the answers
In the interference phase, the tracrRNA-crRNA-Cas9 complex binds to the __________ protein.
In the interference phase, the tracrRNA-crRNA-Cas9 complex binds to the __________ protein.
Signup and view all the answers
Match the following stages of the CRISPR-Cas system with their descriptions:
Match the following stages of the CRISPR-Cas system with their descriptions:
Signup and view all the answers
Which non-coding RNA is involved in the CRISPR-Cas system's defense mechanism?
Which non-coding RNA is involved in the CRISPR-Cas system's defense mechanism?
Signup and view all the answers
The expression phase occurs after the bacterial cell has been exposed to a bacteriophage for the first time.
The expression phase occurs after the bacterial cell has been exposed to a bacteriophage for the first time.
Signup and view all the answers
What happens to the pre-crRNA during the expression phase?
What happens to the pre-crRNA during the expression phase?
Signup and view all the answers
Study Notes
CRISPR-Cas System
- Chinese scientist He Jiankui claimed to use CRISPR to genetically edit babies.
- He offered no evidence or data to support his claims.
- This act could open the door to "designer babies."
RNA Interference (RNAi)
- Double-stranded RNA is more potent at inhibiting mRNA than antisense RNA.
- The phenomenon was termed RNA interference.
- microRNAs (miRNAs): transcribed from endogenous eukaryotic genes and regulate gene expression. miRNAs are partially complementary to their mRNA targets.
- Small interfering RNAs (siRNAs): come from exogenous sources, and are usually perfectly complementary to their target mRNA. They play a role in preventing viral infections.
Non-coding RNAs (ncRNAs) and Gene Regulation
- ncRNAs bind to other molecules and macromolecules.
- ncRNAs have several common functions:
- Scaffold: bind to multiple components, act as scaffold for formation of a complex.
- Guide: guide one molecule to a specific location in the cell.
- Alteration of protein function or stability: bind to ncRNA to affect protein function/stability.
- Ribozyme: RNA molecule with catalytic function, for example peptidyltransferase activity of ribosome.
- Blocker: prevents or blocks a cellular process (binding to ribosomes inhibiting translation).
- Decoy: recognizes other ncRNAs and sequesters them, preventing them from working.
ncRNAs and Human Disease
- Abnormal expression levels of miRNAs have been found in nearly all forms of human cancer.
- Some miRNAs are tumor suppressors, some are oncogenes.
- HOTAIR is expressed in several cancers, behaving as an oncogene when overexpressed.
- Various ncRNAs are associated with neurological disorders (Alzheimer's disease) and cardiovascular diseases (arrhythmias).
ncRNAs in Plant Health
- Abnormalities in ncRNAs play essential roles in plant health.
- Their study is important for agriculture.
- Examples of ncRNAs involved in plant health include miRNA-156, COOLAIR, and IPS1.
Telomeres and DNA Replication
- The ends of linear eukaryotic chromosomes have telomeres composed of repeat sequences (e.g. 5' - GGGTTA-3' in humans)
- Telomeres protect the ends of chromosomes from entanglement and breakage.
- Telomeres shorten with each cell division; when they are too short, the cell can no longer successfully divide, leading to programmed cell death.
- Some cells express telomerase, an enzyme that adds repeating sequence and extends the telomeres.
- Telomeres cannot be fully replicated by DNA polymerase due to the 5' overhang of DNA.
- RNA primers are required for DNA polymerase to begin replication; primers are removed.
- Telomerase is the solution for synthesizing the full length of the top strand, which counteracts the problem of limited DNA replication at the end of DNA strands.
- Telomere length is regulated through TERC, an ncRNA that facilitates the binding of telomerase.
HOTAIR
- HOTAIR is an ncRNA in humans and other mammals
- It regulates transcription by forming a scaffold that binds two protein complexes and guides them to particular genes.
- The protein complexes covalently modify histones, leading to the silencing of target genes.
Signal Recognition Particle (SRP)
- SRP is composed of protein and ncRNA.
- It chaperones the ribosome to the ER.
- As a polypeptide is being made, SRP binds to the ER signal sequence, causing translation to pause.
- SRP binds to an SRP receptor in the ER membrane.
- GTP molecules bound to SRP and the SRP receptor are hydrolyzed, thereby releasing SRP.
- Translation resumes, and the polypeptide is threaded through a channel into the ER lumen.
CRISPR-Cas System (in detail)
- Some bacteria and archaea have a system called the CRISPR-Cas system that defends against bacteriophages (and transposons).
- The type II CRISPR-Cas system was described.
- The system involves three main components:
- Crispr genes (with repeats and spacers)
- TracrRNA (a noncoding RNA)
- Cas genes (encoding associated proteins, e.g., Cas9).
- Defense occurs in three phases:
- Adaptation: after bacterial exposure to a bacteriophage. Cas1 and Cas2 proteins cleave the bacteriophage DNA, and a piece of that DNA is added to the Crispr gene.
- Expression: tracrRNA bonds to complementary sequences of pre-crRNA; pre-crRNA is then cleaved into small crRNA molecules; each tracrRNA-crRNA complex binds to the Cas9 proteins.
- Interference: the tracrRNA-crRNA- Cas9 complex binds to bacteriophage DNA due to complementary base pairing. The Cas9 protein cleaves the bacteriophage DNA, thereby inactivating it.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz explores the functions and characteristics of non-coding RNAs (ncRNAs) and telomerase, including their roles in gene expression and chromosome maintenance. Test your knowledge on the differences between coding and non-coding RNAs, the significance of telomerase, and how ncRNAs regulate various cellular processes.
