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Questions and Answers

What is the primary function of RNA polymerase II in eukaryotic cells?

To bind to ribosomes during translation

To synthesize proteins from mRNA

To initiate transcription from a DNA template (correct)

To process mRNA after transcription

Which of the following correctly differentiates between the sense and antisense strands of DNA?

The sense strand is synthesized from mRNA

The antisense strand serves as the template for mRNA synthesis (correct)

The sense strand contains uracil instead of thymine

The antisense strand has a sequence identical to the mRNA

Which component is NOT required during the translation process in eukaryotic cells?

RNA polymerase II (correct)

Transfer RNA (tRNAs)

Ribosomal RNA (rRNA)

Ribosomal proteins

What is the end product of transcription in eukaryotes?

Messenger RNA (mRNA) Signup and view all the answers

Which part of the gene is recognized by RNA polymerase for initiating transcription?

Transcription start site Signup and view all the answers

What is the primary function of transcription factors in eukaryotic transcription?

To regulate gene expression and initiate transcription Signup and view all the answers

Which of the following is unique to RNA polymerase II's initiation complex?

TATA-binding protein (TBP) Signup and view all the answers

How is RNA synthesized in relation to the DNA template strand?

In the 5'-to-3' direction, using the 3'-to-5' strand as a template Signup and view all the answers

What distinguishes the three types of RNA polymerases found in eukaryotes?

The specific types of RNA they transcribe Signup and view all the answers

Which of the following general transcription factors is necessary for RNA polymerase II to commence transcription?

All general transcription factors are equally necessary Signup and view all the answers

What term describes the initial precursor RNA synthesized during transcription?

pre-mRNA Signup and view all the answers

Which of the following processes is NOT involved in pre-mRNA processing?

Translation Signup and view all the answers

What is the role of the C-terminal domain (CTD) of RNA polymerase during transcription?

Acts as a scaffold for organizing processing factors Signup and view all the answers

What characterizes the relationship between the heterogeneous nuclear RNA (hnRNA) and DNA during transcription?

It is identical in length to the DNA template used Signup and view all the answers

Which molecule is NOT a required component for the translation process in eukaryotic cells?

Transcription factors Signup and view all the answers

What is the primary role of the 5' cap in mRNA processing?

Facilitates ribosomal recognition and binding during translation Signup and view all the answers

Which enzymatic activity is involved in the addition of the poly(A) tail to mRNA?

Poly A polymerase activity Signup and view all the answers

What happens during the formation of the 5' cap on mRNA?

Methyl groups are added to the terminal ribose of the cap Signup and view all the answers

During mRNA processing, where is the cleavage of the primary RNA transcript typically initiated?

Downstream of the AUAAA sequence Signup and view all the answers

Which process is solely responsible for removing introns and connecting exons in mRNA?

RNA splicing Signup and view all the answers

What component is crucial for the removal of introns during mRNA processing?

Splicesome Signup and view all the answers

Which of these statements accurately describes the function of the polysome?

It consists of multiple ribosomes bound to a single mRNA. Signup and view all the answers

What is the role of the nuclear envelope in gene expression?

It facilitates transport of RNA products out of the nucleus. Signup and view all the answers

U6 is classified as which type of molecule?

A ribozyme Signup and view all the answers

What primary feature characterizes the chromatin within the nucleus?

It is tightly packed DNA combined with protein complex. Signup and view all the answers

What is the role of the FG domain in nucleoporins within the nuclear pore complex?

Forms a hydrophobic mesh that regulates macromolecule diffusion Signup and view all the answers

Which statement accurately describes the transport of mature mRNAs across the nuclear envelope?

Mature mRNAs are transported as ribonucleoproteins interacting with nucleoporins Signup and view all the answers

What differentiates the functions of importins and exportins in nuclear transport?

Importins bind to Nuclear Localization Signals, while exportins bind to Nuclear Export Signals Signup and view all the answers

What characteristic of the nuclear pore complex is primarily related to its structural design?

Its octagonal symmetry provides a central channel diameter of 20-40 nm Signup and view all the answers

How do proteins indicate their need for transport across the nuclear envelope?

Through specific amino acid sequences known as Nuclear Localization Signals and Nuclear Export Signals Signup and view all the answers

What is the total number of chromatids present in a human diploid cell before mitosis occurs?

92 chromatids Signup and view all the answers

Which of the following accurately describes a haploid cell?

Has one set of unpaired chromosomes Signup and view all the answers

During the cell cycle, when do sister chromatids become separated into daughter cells?

During mitosis Signup and view all the answers

What is the chromosomal composition of a human diploid cell?

23 pairs of homologous chromosomes Signup and view all the answers

Which term refers to the structure that organizes DNA and proteins in a cell?

Chromosome Signup and view all the answers

Which statement accurately describes the role of co-activators in gene expression?

They bind directly to DNA. Signup and view all the answers

What function does the iron regulatory protein (IRP) perform when iron levels are low?

It inhibits the translation of Ferritin mRNA. Signup and view all the answers

Which component is NOT involved in the mechanism of RNA interference?

Histones Signup and view all the answers

Which structure is primarily responsible for peptide degradation within the cell?

Proteasome Signup and view all the answers

Which of the following concepts primarily illustrates the influence of both genetic and environmental factors on health?

Epigenetics Signup and view all the answers

What is a characteristic feature of semi-conservative DNA replication?

Each daughter strand contains one parental strand. Signup and view all the answers

During which phase of the cell cycle does DNA replication primarily occur in eukaryotic cells?

S phase Signup and view all the answers

Which of the following best describes the role of DNA polymerase during DNA replication?

It synthesizes new DNA strands. Signup and view all the answers

What is the significance of replication foci in eukaryotic DNA replication?

Regions where several replicons become active. Signup and view all the answers

How does the replication fork function during DNA replication?

It facilitates nucleotide incorporation into new strands. Signup and view all the answers

What is the role of DNA Polymerase III during DNA replication in prokaryotes?

It extends RNA primers to create Okazaki fragments. Signup and view all the answers

Which protein complex initiates DNA replication in eukaryotic cells by recognizing the origin of replication?

Origin recognition complex (ORC) Signup and view all the answers

What mechanism is primarily used to alleviate DNA supercoiling during replication in eukaryotic cells?

Type I topoisomerases Signup and view all the answers

What is the function of RNA primers during DNA replication?

To begin the synthesis of Okazaki fragments. Signup and view all the answers

In bacterial cells, which protein is primarily responsible for unwinding the DNA strands at the origin of replication?

DnaB helicase Signup and view all the answers

What type of mutation results in a change in the amino acid sequence due to a premature stop codon?

Nonsense mutation Signup and view all the answers

Which type of mutation can potentially lead to the alteration of the reading frame during protein synthesis?

Insertion and deletion mutation Signup and view all the answers

Which of the following mutations is characterized by the replacement of one amino acid with another that has different properties?

Missense mutation Signup and view all the answers

What is the immediate molecular consequence of a frameshift caused by a deletion mutation?

Altered downstream codons Signup and view all the answers

Which type of genetic mutation is associated with Sickle Cell Anemia?

Point mutation Signup and view all the answers

What is the primary consequence of a repeat expansion in the HHT gene?

Formation of protein aggregates leading to toxicity Signup and view all the answers

Which type of mutation is characterized by a permanent alteration in the nucleotide sequence of DNA?

Genetic mutation Signup and view all the answers

Which condition results specifically from nondisjunction during meiosis?

Down Syndrome Signup and view all the answers

How does the duplication of the MYC gene contribute to cancer progression?

By promoting cell growth and proliferation Signup and view all the answers

What type of chromosomal abnormality is exemplified by chromosome inversions and translocations?

Structural abnormalities Signup and view all the answers

What is the consequence of protein phosphorylation in cell signaling?

Can lead to increased protein-protein interactions Signup and view all the answers

Which type of receptor is primarily involved in signaling pathways that require the phosphorylation of tyrosine residues?

Receptor protein-tyrosine kinases (RTKs) Signup and view all the answers

How does the alteration of protein conformation by phosphorylation generally influence enzyme function?

It can either activate or inactivate the enzyme depending on the protein Signup and view all the answers

What aspect of cell activity can be directly triggered by the signaling cascade involving phosphorylation?

Protein stability leading to enhanced cell mobility Signup and view all the answers

What role do kinases play in cell signaling pathways?

Phosphorylate proteins to activate or modify their function Signup and view all the answers

Which type of cell signaling involves a cell sending and responding to the same message?

Autocrine signaling Signup and view all the answers

What happens to the receptor when a ligand binds to it?

It undergoes a conformational change. Signup and view all the answers

Which of these is NOT considered an extracellular messenger molecule?

ATP Signup and view all the answers

How do second messengers function in signal transduction?

They activate or inactivate target proteins within the cell. Signup and view all the answers

What is the primary distinction between paracrine and endocrine signaling?

Paracrine signaling affects nearby cells, while endocrine signaling affects distant targets through the bloodstream. Signup and view all the answers

Which G protein is responsible for activating phospholipase C to increase IP3 and DAG levels?

Gq Signup and view all the answers

What is the effect of cAMP on the activity of Protein Kinase A (PKA)?

cAMP activates PKA by binding to its regulatory subunits. Signup and view all the answers

What role does the cAMP response element-binding protein (CREB) play in cell signaling?

It acts as a transcription factor that promotes gene expression. Signup and view all the answers

Which statement correctly describes the action of glucagon or epinephrine in liver cells?

They activate gluconeogenesis via cAMP signaling. Signup and view all the answers

What is the primary downstream effect of Gq protein activation in cell signaling pathways?

Activation of phospholipase C to generate secondary messengers. Signup and view all the answers

What is the role of phospholipase C in the signaling pathway involving G Protein-Coupled Receptors?

It cleaves phosphatidylinositol di-phosphate (PIP2) to generate second messengers. Signup and view all the answers

During the activation of rod cells in response to light, what effect does the reduction of cytosolic cGMP have?

It results in membrane hyperpolarization. Signup and view all the answers

Which statement about the second messenger cAMP is correct?

cAMP is synthesized by adenylyl cyclase and regulates various cellular processes. Signup and view all the answers

Bradyopsia is a condition linked to mutations in which gene involved in light signaling?

RGS9, which typically helps to inactivate transducin. Signup and view all the answers

In the context of GPCR signaling, which statement accurately represents the function of Gαt?

Gαt triggers the activation of cGMP phosphodiesterase during light stimulation. Signup and view all the answers

Which type of receptor is specifically involved in the activation of ion passage through membranes?

Ligand gated channels Signup and view all the answers

Which molecule is directly produced from the action of adenylyl cyclase when activated by GPCRs?

cyclic AMP (cAMP) Signup and view all the answers

What is the main role of protein kinase A (PKA) in cellular signaling through cAMP?

Phosphorylating target proteins Signup and view all the answers

What secondary messenger is generated from the cleavage of PIP2 during GPCR signaling?

IP3 and DAG Signup and view all the answers

Which subunit of the G-protein is responsible for activating adenylyl cyclase in the cAMP signaling pathway?

Alpha subunit Gs Signup and view all the answers

What is a primary function of second messengers in cellular signaling?

Activate/inactivate target proteins Signup and view all the answers

Which type of receptor is characterized by having an intracellular domain with tyrosine protein kinase activity?

Receptor protein-tyrosine kinases Signup and view all the answers

Which of the following ligands is NOT typically associated with receptor protein-tyrosine kinases?

Nerve Growth Factor (NGF) Signup and view all the answers

What is the initial step in the activation of receptor protein-tyrosine kinases following ligand binding?

Ligand-mediated dimerization Signup and view all the answers

Which of the following statements about HER2-positive breast cancer is true?

It tests positive for human epidermal growth factor receptor 2. Signup and view all the answers

Study Notes

Eukaryotic Transcription Overview

Eukaryotic transcription differs significantly from prokaryotic transcription, lacking a well-defined termination sequence in eukaryotes.
Eukaryotic transcription involves multiple RNA polymerases (I, II, and III) with slightly different functions.
The process starts with the binding of RNA polymerase II to the promoter region of the DNA.
Specific proteins, called transcription factors, interact with the promoter and help regulate the rate of transcription.
General transcription factors are essential for initiation.
The pre-initiation complex (PIC) forms, including RNA polymerase II (RNAPII) and other general transcription factors.
The process can be regulated by various upstream regulatory elements called enhancers and silencer elements
Eukaryotic transcription involves multiple steps including initiation, elongation, and termination
Elongation involves the addition of new nucleotides to the growing RNA transcript.
Termination is less well-defined but often involves a polyadenylation signal.

Eukaryotic Transcription: Initiation

The pre-initiation complex (PIC) formation initiates eukaryotic transcription
The TATA box, a critical promoter element, assists RNA polymerase II in binding to the initiation site.
TFIIB, TFIIA, TATA-binding protein (TBP), along with other basal transcription factors, assemble at the core promoter to aid in RNA polymerase II binding.
Once the pre-initiation complex is formed, transcription begins, marking the beginning of the elongation phase.

Eukaryotic Transcription: Elongation

During elongation, RNA polymerase II continues sliding along the DNA template, adding nucleotides to the growing RNA molecule.
The DNA-RNA hybrid forms, which stabilizes the elongation process.
Around 20-50 nucleotides are incorporated into the mRNA per second, driven by ATP or similar energy-rich molecules within the complex
Topoisomerases assist in relieving the strain on the DNA molecule, allowing the process to continue in a streamlined manner.
The carboxyl-terminal domain (CTD) of RNA polymerase II is involved in facilitating interactions with other proteins, impacting elongation and subsequent processes.

Eukaryotic Transcription: Termination

Transcription termination in eukaryotes is a less well-defined process compared to prokaryotic termination, often involving a polyadenylation signal sequence (PAS).
AAUAAA is a common PAS sequence that signals where the RNA transcript will be cleaved, initiating the termination phase.
Following cleavage of the transcript, the mRNA undergoes a polyadenylation process by adding an adenine tail (poly(A) tail) to maintain its stability which contributes to the process of mRNA export

Eukaryotic Transcription Factors

Transcription factors are proteins that bind to specific DNA sequences and regulate transcription
General transcription factors (GTFs): are essential for the binding of RNA polymerase to the promoter, while other proteins modulate the exact steps of initiation
Specific transcription factors modulate the expression according to the organism’s need

Core Promoter Elements

Core promoters contain crucial elements, such as the TATA box, initiator element (Inr), and downstream promoter element (DPE), that regulate RNA polymerase II binding and initiation.
Their precise locations and sequences influence the efficiency and specificity of transcription initiation, and they are crucial elements for regulating gene expression
The core promoter’s location often is relative to the transcription start site (TSS) which can vary and often is several bases upstream of the TSS

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Description

This quiz explores the intricate process of eukaryotic transcription, highlighting its differences from prokaryotic systems. Delve into the roles of RNA polymerases, transcription factors, and regulatory elements involved in the initiation, elongation, and termination of transcription.