p.21
Nuclear Structure and Components
What is nuclear protoplasm?
A viscous matrix containing chromosomes and nucleoli.
p.11
Nuclear Envelope and Pores
What is the cytoplasmic ring?
A structure located around the cytoplasmic margin of the nuclear pore.
p.15
Transport Mechanisms in the Nucleus
What are nucleocytoplasmic shuttling signals?
Transport signals recognized by transporter proteins.
p.35
Nuclear Structure and Components
What is the total number of homologous pairs in the human genome?
23 homologous pairs, or 46 chromosomes.
p.15
Transport Mechanisms in the Nucleus
What do exportins recognize to facilitate transport?
Nuclear export sequences.
p.1
Nucleolus Function and Structure
What is the function of the nucleolus?
It is the site of rRNA synthesis and contains transcriptionally active DNA for ribosomes.
p.63
Chromatin Organization: Euchromatin and Heterochromatin
Which option describes the functional significance of the dark-stained chromatin observed in the kidney biopsy?
Organization of inactive chromatin.
p.42
Gene Regulation and Expression
What happens to one female X chromosome in relation to lincRNAs?
It is transcribed to form lincRNAs that coat that X chromosome and prevent the transcription of its genes.
p.1
Nuclear Envelope and Pores
What are nuclear pores?
Openings in the nuclear envelope that connect the nucleus with the cytoplasm.
p.30
DNA Structure and Function
What does telomerase do?
Adds repeated nucleotide sequences to the telomere ends.
p.63
RNA Types and Functions
What is ribosomal RNA biosynthesis?
It is the process of synthesizing rRNA, which is essential for ribosome formation.
p.24
Gene Regulation and Expression
What are exons?
Regions of DNA that code for specific RNAs.
p.43
RNA Types and Functions
From where do siRNAs frequently arise?
From the genome of RNA viruses that infect a cell.
p.57
Chromatin Organization: Euchromatin and Heterochromatin
What is heterochromatin?
A tightly packed form of DNA that is generally not active in transcription.
p.43
RNA Types and Functions
Can siRNAs be transcribed from the cell's own genome?
Yes, some siRNAs are transcribed from the cell’s own genome.
p.57
Nuclear Envelope and Pores
What is the function of the outer nuclear membrane?
It serves as a barrier and is involved in transport but not in transcription.
p.21
Nuclear Structure and Components
What regulates calcium signals in the nucleus?
Receptors for inositol 1,4,5-triphosphate.
p.19
Nucleolus Function and Structure
What functions does nucleostemin have?
It regulates the cell cycle and cell differentiation.
p.39
Nucleolus Function and Structure
What is the role of rRNA in ribosome formation?
It associates with many different proteins to form ribosomes.
p.13
Nuclear Envelope and Pores
What characteristic does the lumen of the nuclear pore have?
It may be a gated channel that impedes passive diffusion.
p.7
Nuclear Envelope and Pores
How is the perinuclear space related to the rough endoplasmic reticulum (rER)?
It is continuous with the rER cisterna.
p.41
RNA Types and Functions
When were miRNAs first discovered?
In the 1990s in roundworms.
p.37
RNA Types and Functions
What is the primary function of mRNA?
Carries the genetic code to the cytoplasm to direct protein synthesis.
p.13
Nuclear Envelope and Pores
What is the role of the transmembrane proteins in the nuclear pore?
They project into the lumen of the nuclear pore, anchoring the complex into the pore rim.
p.14
Transport Mechanisms in the Nucleus
What type of movement does the nuclear envelope permit?
Passive movement via a 9- to 11-nm open channel for simple diffusion.
p.9
Nuclear Envelope and Pores
What do the protein subunits surrounding the nuclear pore represent?
They represent the structural components of the nuclear pore complex.
p.4
Nuclear Lamina and Lamins
What is the role of the nuclear lamina?
It provides structural support to the nucleus.
p.41
Gene Regulation and Expression
What is the primary function of miRNAs?
To regulate gene expression.
p.6
Nuclear Envelope and Pores
What does the nuclear envelope direct the formation of?
Nuclear pore complexes (NPCs).
p.24
DNA Structure and Function
What structure does DNA form?
A double helix consisting of two complementary strands.
p.12
Nuclear Envelope and Pores
Where is the nucleoplasmic ring located?
Around the nucleoplasmic margin of the nuclear pore.
p.6
Nuclear Lamina and Lamins
What results in the reassembly of lamins?
Dephosphorylation of lamins.
p.13
Nuclear Envelope and Pores
How many transmembrane proteins are involved in the luminal spoke ring?
Eight transmembrane proteins.
p.3
Nuclear Structure and Components
What do the ribosomes on the outer nuclear membrane synthesize?
Proteins that enter the perinuclear cisterna.
p.35
Nuclear Structure and Components
What does karyotype refer to?
The number and morphology of chromosomes.
p.37
RNA Types and Functions
What do codons in mRNA correspond to?
They are complementary to the DNA codons from which it was transcribed.
p.31
Chromatin Organization: Euchromatin and Heterochromatin
What is chromatin composed of?
DNA complexed with histones and nonhistone proteins.
p.25
Gene Regulation and Expression
What is a genome?
The complete set of hereditary information that an individual possesses.
p.61
Cell Cycle and Cancer Biology
Which option is NOT a nuclear protein related to cellular senescence?
Rb tumor suppressor protein.
p.34
DNA Structure and Function
What type of DNA sequences does Giemsa specifically stain?
DNA sequences rich in adenine (A) and thymine (T).
p.14
Transport Mechanisms in the Nucleus
What are nuclear localization segments?
Clusters of certain amino acids that act as signals for transport.
p.20
Nucleolus Function and Structure
What occurs during the preliminary assembly in the nucleolus?
Assembly of ribosome subunit precursors.
p.6
Nuclear Envelope and Pores
What is the responsibility of the nuclear envelope during mitosis?
Disassembly and reassembly of the nuclear envelope.
p.6
Nuclear Lamina and Lamins
What leads to the disassembly of lamins?
Phosphorylation of lamins.
p.24
DNA Structure and Function
What holds the two strands of the DNA double helix together?
Hydrogen bonds between the base pairs A – T and G – C.
p.8
Nuclear Envelope and Pores
What are nuclear pores associated with?
The nuclear pore complex (NPC).
p.40
RNA Types and Functions
What is micro-RNA (miRNA)?
A small non-coding RNA molecule that regulates gene expression.
p.40
RNA Types and Functions
What does lincRNA stand for?
Large/long intergenic noncoding RNA.
p.42
Gene Regulation and Expression
What is one function of lincRNAs?
They function in gene regulation.
p.24
DNA Structure and Function
What is a codon?
A sequence of three bases in the DNA that codes for a single amino acid.
p.12
Nuclear Envelope and Pores
Where is the distal ring attached?
To the distal end of the nuclear basket.
p.13
Nuclear Envelope and Pores
What is a luminal subunit?
A moiety of each transmembrane protein that projects into the perinuclear cistern.
p.31
Chromatin Organization: Euchromatin and Heterochromatin
In what forms does chromatin exist in the nucleus?
As heterochromatin and euchromatin.
p.27
Chromatin Organization: Euchromatin and Heterochromatin
What components make up a nucleosome?
Histones and nonhistone proteins.
p.25
Gene Regulation and Expression
What is a gene?
A segment of DNA that contains information for encoding a single mRNA molecule and regulatory sequences that control trait expression.
p.41
Gene Regulation and Expression
How do some miRNAs prevent transcription?
By methylating specific regions of DNA.
p.23
DNA Structure and Function
What is the primary function of DNA?
Stores genetic information and acts as a template for the synthesis of RNA.
p.10
Nuclear Envelope and Pores
What are the names of the rings in the nuclear pore complex?
Cytoplasmic ring, luminal spoke ring, nuclear ring, distal ring.
p.15
Transport Mechanisms in the Nucleus
What role do Ran proteins play in nucleocytoplasmic transport?
They regulate the functions of exportins and importins.
p.3
Nuclear Envelope and Pores
With which structure is the outer nuclear membrane continuous at certain sites?
Rough endoplasmic reticulum.
p.23
DNA Structure and Function
What is the structure of DNA?
A long double-stranded helical linear molecule of nucleotides.
p.35
Nuclear Structure and Components
What is characteristic of a karyotype?
It is characteristic for each species.
p.38
RNA Types and Functions
What is the primary function of tRNA?
Involved in protein synthesis.
p.23
DNA Structure and Function
What are the components of a nucleotide?
A base (purine or pyrimidine), deoxyribose sugar, and a phosphate group.
p.5
Nuclear Lamina and Lamins
What are nuclear lamins?
A specialized type of nuclear intermediate filament (type V) consisting of lamins A, B1, B2, and C.
p.43
RNA Types and Functions
How do siRNAs resemble miRNAs?
They resemble miRNAs in their mode of action.
p.3
Nuclear Lamina and Lamins
What surrounds the cytoplasmic aspect of the outer nuclear membrane?
A loosely arranged mesh of intermediate filaments (vimentin).
p.6
Nuclear Envelope and Pores
What is the role of the nuclear envelope in the cell?
It organizes nuclear envelope and chromatin.
p.20
Nucleolus Function and Structure
What role does nucleostemin play in the cell cycle?
Cell cycle checkpoint signaling.
p.8
Nuclear Envelope and Pores
How many nuclear pores can be found in a cell?
From dozens to thousands, depending on metabolic activity.
p.57
Nuclear Envelope and Pores
Which component is associated with the nuclear pore complex?
It facilitates transport but is not the site of transcriptional activity.
p.45
Transport Mechanisms in the Nucleus
How do proteins pass through the nuclear pore complex?
Via receptor-mediated transport.
p.24
Gene Regulation and Expression
What are introns?
Regions of DNA that do not code for RNAs but serve important regulatory functions.
p.38
RNA Types and Functions
What is located at the terminal end of tRNA?
Adenylic acid (where amino acids attach).
p.15
Transport Mechanisms in the Nucleus
What do importins recognize for transporting molecules into the nucleus?
Nuclear localization sequences.
p.14
Transport Mechanisms in the Nucleus
How do most proteins pass through the nuclear envelope?
By receptor-mediated transport, regardless of size.
p.61
Cell Cycle and Cancer Biology
What is the focus of the talk at the national meeting on regenerative medicine?
Cellular senescence and cancer.
p.20
Nucleolus Function and Structure
What is processed in the nucleolus related to micro RNAs?
Primary processing of micro RNAs.
p.45
Transport Mechanisms in the Nucleus
What is the function of the nuclear pore complex?
It permits free communication between the nucleus and the cytoplasm.
p.35
Nuclear Structure and Components
How many pairs of sex chromosomes are in the human genome?
1 pair (either XX or XY).
p.42
RNA Types and Functions
What are lincRNAs?
Long intergenic non-coding RNAs that are more than 200 nucleotides in length.
p.28
Chromatin Organization: Euchromatin and Heterochromatin
What structure do nucleosomes help package into?
A solenoid-like structure, which is a thick 30-nm fiber.
p.22
Chromatin Organization: Euchromatin and Heterochromatin
What are interchromatin granules?
Clusters of particles containing RNP and various enzymes.
p.63
Chromatin Organization: Euchromatin and Heterochromatin
What does the dark-stained ring of marginal chromatin in the nucleus of an endothelial cell indicate?
Organization of inactive chromatin.
p.13
Nuclear Envelope and Pores
What is the function of the luminal spoke ring in the nuclear pore complex?
It interposes between the cytoplasmic and nucleoplasmic rings.
p.31
Gene Regulation and Expression
How does the euchromatin/heterochromatin ratio in malignant cells compare to normal cells?
It is higher in malignant cells than in normal cells.
p.61
Cell Cycle and Cancer Biology
What is the role of telomerase in cancer cells?
It enables cancer cells to continue to proliferate and maintain genomic stability.
p.41
Gene Regulation and Expression
What do other miRNAs do to mRNA strands?
They insert into a matching portion, preventing translation.
p.57
Nucleolus Function and Structure
What is the role of the nucleolus?
It is involved in ribosome production, not directly in transcriptional activity.
p.53
Nuclear Envelope and Pores
What is the function of the nuclear pore complex?
It regulates the transport of molecules between the nucleus and the cytoplasm.
p.19
Nucleolus Function and Structure
Which rRNA subunits are assembled in the pars granulosa?
18S rRNA and 28S rRNA subunits.
p.30
DNA Structure and Function
What does telomere length indicate?
The lifespan of the cell.
p.53
Chromatin Organization: Euchromatin and Heterochromatin
What is heterochromatin?
A tightly packed form of DNA that is transcriptionally inactive.
p.53
Chromatin Organization: Euchromatin and Heterochromatin
What is euchromatin?
A loosely packed form of DNA that is transcriptionally active.
p.42
RNA Types and Functions
How do lincRNAs interact with mRNAs?
They compete with certain mRNAs for miRNAs.
p.18
Nucleolus Function and Structure
What types of DNA are found in the Pars fibrosa?
Transcriptionally active DNA and ribosomal genes.
p.26
DNA Structure and Function
Why is negatively supercoiled DNA important?
It is required for most biological reactions.
p.36
RNA Types and Functions
What sugar does RNA contain?
Ribose instead of deoxyribose.
p.25
Gene Regulation and Expression
How are genes classified?
Into protein coding genes and noncoding segments of DNA.
p.1
Nuclear Structure and Components
What are the main components of the nucleus?
Chromatin, nucleolus, nuclear envelope, nuclear pores, and nucleoplasm.
p.23
DNA Structure and Function
What are the purines found in DNA?
Adenine (A) and Guanine (G).
p.35
Nuclear Structure and Components
What are chromosomes composed of?
Two chromatids joined together at the centromere.
p.42
Gene Regulation and Expression
How do lincRNAs affect transcription on different chromosomes?
They prevent the transcription of various genes on different chromosomes.
p.34
Gene Regulation and Expression
What is G-banding used for?
To identify chromosomes and chromosomal anomalies.
p.63
Cell Cycle and Cancer Biology
What is the role of the kinetochore complex?
It is involved in chromosome segregation during cell division.
p.26
DNA Structure and Function
What is a supercoiled structure?
A helix twisted around itself in three-dimensional space.
p.22
RNA Types and Functions
What are small nuclear RNPs (snRNPs)?
Complexes of proteins and small RNAs involved in hnRNP splicing or in cleavage reactions.
p.32
Chromatin Organization: Euchromatin and Heterochromatin
What is euchromatin?
Transcriptionally active chromatin.
p.32
Chromatin Organization: Euchromatin and Heterochromatin
How does euchromatin appear in a transmission electron microscope (TEM)?
As electron-lucent regions.
p.36
RNA Types and Functions
What type of molecule is RNA?
Single stranded linear molecule.
p.36
RNA Types and Functions
What are ribozymes?
RNAs that can act as enzymes, catalyzing the formation of peptide bonds during protein synthesis.
p.45
Nuclear Envelope and Pores
Where is the nuclear pore complex located?
Only at specific nuclear pore sites.
p.19
Nucleolus Function and Structure
What is the composition of the pars granulosa?
It is composed of maturing ribosomal precursor particles.
p.59
Nucleolus Function and Structure
What is the function of the nucleolus?
It is involved in ribosome production, but it is not a clump of nucleoprotein near the periphery.
p.1
Chromatin Organization: Euchromatin and Heterochromatin
What is the difference between euchromatin and heterochromatin?
Euchromatin is transcriptionally active DNA, while heterochromatin is more condensed and less active.
p.59
Nuclear Envelope and Pores
What is the outer nuclear membrane?
It is a membrane surrounding the nucleus, not a clump of nucleoprotein.
p.23
DNA Structure and Function
What are the pyrimidines found in DNA?
Cytosine (C) and Thymine (T).
p.26
DNA Structure and Function
What type of structure do mitochondrial DNA and most prokaryotic DNA have?
Closed circular structures.
p.32
Chromatin Organization: Euchromatin and Heterochromatin
How is heterochromatin formed?
From euchromatin that is folded into 30-nm thick filaments.
p.42
RNA Types and Functions
What role do lincRNAs play in relation to miRNAs?
They act as decoys that protect mRNAs from the inhibitory actions of miRNAs.
p.39
Nucleolus Function and Structure
What forms the large (60S) subunit of the ribosome?
The RNP containing 28S and 5.8S rRNA combines with 5S rRNA.
p.21
Nuclear Structure and Components
What are the main components of nuclear protoplasm?
Macromolecules, ions, transcriptional processing apparatus, and nucleoplasmic reticulum.
p.21
Nuclear Structure and Components
What is the relationship between the nucleoplasmic reticulum and the nuclear envelope?
The nucleoplasmic reticulum is continuous with the nuclear envelope and endoplasmic reticulum.
p.38
RNA Types and Functions
How many nucleotides does tRNA contain approximately?
Approximately 80 nucleotides.
p.8
Nuclear Envelope and Pores
What do nuclear pores permit?
Passage of certain molecules in either direction.
p.11
Nuclear Envelope and Pores
What is the composition of the filament in the cytoplasmic ring?
Made of a Ran-binding protein (GTP-binding protein).
p.11
Transport Mechanisms in the Nucleus
What is the potential function of the filaments in the cytoplasmic ring?
They may serve as a staging area prior to protein transport.
p.1
Nuclear Envelope and Pores
What is the structure of the nuclear envelope?
It consists of a double membrane with an inner and outer membrane separated by a perinuclear cisternal space.
p.5
Nuclear Lamina and Lamins
How does Lamin B interact with the nuclear structure?
It attaches the lattice to the inner nuclear membrane via lamin receptors.
p.19
Nucleolus Function and Structure
What is the role of the nucleolar matrix?
It is a fiber network involved in the organization of the nucleolus.
p.26
DNA Structure and Function
What causes supercoiling in DNA?
Strain on the molecule caused by under- or overwinding the double helix.
p.32
Chromatin Organization: Euchromatin and Heterochromatin
How does heterochromatin appear in a transmission electron microscope (TEM)?
As electron-dense regions.
p.8
Nuclear Envelope and Pores
How are nuclear pores formed?
By the fusion of the inner and outer nuclear membranes.
p.12
Transport Mechanisms in the Nucleus
What is the function of the distal ring?
Assists in the export of RNA into the cytoplasm.
p.18
Nucleolus Function and Structure
What are the four distinct regions of the nucleolus?
Fibrillar centers (FC), Pars fibrosa (F), and others.
p.22
Chromatin Organization: Euchromatin and Heterochromatin
What are perichromatin granules?
Single dense granules surrounded by a less dense halo, located at the periphery of heterochromatin.
p.5
Nuclear Lamina and Lamins
What structure do lamins A and C form?
An orthogonal lattice/meshwork.
p.26
DNA Structure and Function
What are the two forms in which mitochondrial DNA can exist?
Relaxed circles or supercoiled structures.
p.1
Nuclear Structure and Components
What is nucleoplasm?
The nuclear content other than the chromatin and nucleolus.
p.33
Chromatin Organization: Euchromatin and Heterochromatin
What happens to chromatin during mitosis and meiosis?
It condenses, making chromosomes visible.
p.33
Chromatin Organization: Euchromatin and Heterochromatin
What does histone H1 do in condensed chromatin?
It wraps around groups of nucleosomes.
p.33
Chromatin Organization: Euchromatin and Heterochromatin
What is the structural unit of a chromosome?
The 30-nm diameter filaments of helical coils.
p.16
Nucleolus Function and Structure
What are nucleolar organizer regions (NORs)?
Portions of chromosomes where rRNA genes are located.
p.40
RNA Types and Functions
What is the function of small interfering RNAs (siRNAs)?
They play a role in RNA interference and gene silencing.
p.32
Chromatin Organization: Euchromatin and Heterochromatin
What is heterochromatin?
Condensed chromatin that is not being transcribed.
p.40
RNA Types and Functions
How do miRNAs regulate gene expression?
By binding to complementary sequences on target mRNAs, leading to their degradation or inhibition.
p.33
Chromatin Organization: Euchromatin and Heterochromatin
When are chromosomes visible with light microscopy?
Only during mitosis and meiosis.
p.42
Gene Regulation and Expression
What is the outcome of lincRNAs protecting mRNAs?
They facilitate the translation of the mRNA to synthesize a particular protein.
p.64
Cell Cycle and Cancer Biology
What are the key regulatory protein complexes in regulating the cell cycle?
Cyclin B and Cyclin dependent kinase - 2.
p.59
Chromatin Organization: Euchromatin and Heterochromatin
What is euchromatin?
A less condensed form of chromatin that is actively involved in transcription, not concentrated near the periphery.
p.22
Chromatin Organization: Euchromatin and Heterochromatin
What do perichromatin granules contain?
4.7S RNA and two peptides similar to those found in heterogeneous nuclear RNPs (hnRNPs).
p.18
Nucleolus Function and Structure
What is the role of RNA polymerase I in the nucleolus?
It is responsible for the transcription of rRNA.
p.63
DNA Structure and Function
What is the function of nucleosome assembly?
It helps in the packaging of DNA into chromatin.
p.32
Chromatin Organization: Euchromatin and Heterochromatin
What is the Barr body?
The condensed form of one of the two X chromosomes in female mammals.
p.26
DNA Structure and Function
What characterizes negatively supercoiled DNA?
DNA is wound more loosely than in Watson-Crick DNA.
p.18
Nucleolus Function and Structure
Which proteins are associated with the nucleolus?
Fibrillarin and nucleolin.
p.39
Nucleolus Function and Structure
What forms the small (40S) subunit of the ribosome?
The RNP containing 18S rRNA.
p.38
RNA Types and Functions
What does each tRNA combine with?
A specific amino acid that has been activated by an enzyme.
p.43
Gene Regulation and Expression
What effect do siRNAs have on DNA?
They methylate specific regions of the DNA and interfere with transcription.
p.22
RNA Types and Functions
What are hnRNP particles?
Heterogeneous nuclear RNA (hnRNA) complexes of precursor mRNA (pre-mRNA) and proteins of variable densities.
p.40
RNA Types and Functions
What is the primary role of siRNAs?
To mediate the degradation of mRNA and prevent translation.
p.63
Cell Cycle and Cancer Biology
What is the purpose of a DNA replication center?
It is where DNA replication occurs during the cell cycle.
p.18
Nucleolus Function and Structure
What significant quantity is found in the Pars fibrosa?
Substantial quantity of rRNA.
p.16
Nucleolus Function and Structure
What is primarily observed in interphase cells?
The structure of the nucleolus, which is actively synthesizing proteins.
p.16
Nucleolus Function and Structure
Which human chromosomes contain nucleolar organizer regions?
Chromosomes 13, 14, 15, 21, and 22.
p.36
RNA Types and Functions
What types of RNA can be formed from noncoding segments of DNA?
tRNA, rRNA, and regulatory RNAs.
p.18
Nucleolus Function and Structure
What composes the Fibrillar centers (FC) of the nucleolus?
Nucleolar organizer regions (NORs) and ribonucleoprotein (RNP) signal recognition particle.
p.19
Nucleolus Function and Structure
In which types of cells are large quantities of nucleostemin present?
In cancer cells and stem cells.
p.22
RNA Types and Functions
What is the role of hnRNP particles?
Involved in pre-mRNA processing.
p.39
Nucleolus Function and Structure
What is the initial precursor rRNA called?
45S precursor rRNA (pre-rRNA).
p.64
Chromatin Organization: Euchromatin and Heterochromatin
What does a Barr body represent in a nucleus?
Facultative heterochromatin.
p.40
RNA Types and Functions
What is the significance of lincRNAs?
They are involved in regulating gene expression and chromatin organization.
p.5
Nuclear Lamina and Lamins
What is the role of emerin in relation to lamins?
Emerin binds both lamin A and B.
p.64
Cell Cycle and Cancer Biology
What is the role of telomerase in cells?
It is essential for cellular lifespan.
p.26
DNA Structure and Function
What characterizes positively supercoiled DNA?
DNA is wound more tightly than in Watson-Crick DNA.
