©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
MCB*2050 Final Exam Key Terms with
Complete Solutions
Nucleus - ✔✔Control center of the cell. Contains DNA. Largest
organelle. Responsible for 1) compartmentalizations of the cellular genome
and its activities and 2) coordination of cellular activities
Nucleoplasm - ✔✔Fluid-filled interior of the nucleus - highly organized.
Consists of >30 specialized regions ('subdomains') that participate in
specific functions
Nucleoid - ✔✔Prokaryotes possess this region where the chromosome is
located. There's less DNA, less DNA packaging and little/no RNA
processing.
Nucleolus - ✔✔Most obvious nuclear subdomain. Irregular shape, dense
and granular in appearance. Functions in producing ribosomes. Site of
ribosomal DNA (rDNA) gene transcription, RNA processing, and initial
stages of ribosomal subunit (rRNA + protein) assembly
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
Transcription factories - ✔✔Active genes (euchromatin) from different
subdomains/regions of the same chromosome extend into
interchromosomal channels to form this. This is where transcription factors
are concentrated.
Interchromosomal channel - ✔✔Regions between subdomains that
serve as barriers to prevent unwanted DNA-DNA and/or DNA/protein
interactions
Nuclear speckle - ✔✔Subdomains where mRNA splicing factors are
concentrated (where pre-mRNA processing occurs). They appear as
speckles under fluorescent microscopy. Often located in interchromosomal
channels next to transcription factors. Numerous and highly dynamic. >50
in number. Can move quickly and grow/shrink depending on the needs of
the cell
Nuclear matrix - ✔✔Insoluble fibrillar-like protein network ('mesh')
distributed throughout the nucleoplasm. Analogous to the cytoskeleton
network in the cytoplasm. Has a structural role: maintains the overall shape
of the nucleus. Serves as a scaffold - responsible for organizing nuclear
subdomains and anchoring protein factors. Very little known about its
composition and assembly/disassembly.
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
Cytoskeleton network - ✔✔Located in the cytoplasm. Analogous to the
nuclear matrix. Composed of three major filament systems: microtubules,
actin microfilaments, and intermediate filaments.
Nuclear envelope - ✔✔Separates nuclear contents from the surrounding
cytoplasm. Acts as a barrier - requires the regulated passage of molecules
(e.g. RNA and proteins) between the nucleus and cytoplasm. Establishes
the unique composition of the nucleus and spatially regulates gene
expression. Provides the structural framework for the nucleus. Sandwiched
between the inner and outer membrane. Composed of three main parts:
nuclear membranes, nuclear lamina, nuclear pore complex.
Inner nuclear membrane - ✔✔Unique protein composition. One of the
concentric membranes (phospholipid bilayers). Directly beside the nuclear
envelope. Joins other membrane at nuclear pore complex. Sits in parallel to
the other membrane. Serves as a barrier to the passage of ions, solutes,
and macromolecules between the nucleoplasm and cytoplasm.
Outer nuclear membrane - ✔✔Continuous with RER. Ribosomes
attached to cytoplasmic surface of it. One of the concentric membranes
(phospholipid bilayers). Directly beside the nuclear envelope. Joins other
membrane at nuclear pore complex. Sits in parallel to the other membrane.
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
Serves as a barrier to the passage of ions, solutes, and macromolecules
between the nucleoplasm and cytoplasm
Nuclear envelope lumen - ✔✔Separates the inner and outer membrane.
10-50 nm diameter. Continuous with the ER lumen.
Nuclear lamina - ✔✔Located on the inner surface of the nuclear inner
membrane. Network ('mesh') of long, filament-like proteins. Provides
mechanical support to nuclear envelope (binds to nuclear inner membrane
integral proteins). Serves as a scaffold for attachment of chromatin and
nuclear matrix to the nuclear envelope.
ABC nuclear lamins - ✔✔Evolutionary related to proteins that form
intermediate filaments in the cytoskeleton network.
Nuclear pore complex (NPC) - ✔✔Channels/doorways in the nuclear
envelope. Responsible for the regulated trafficking of all
substances between the nucleus and cytoplasm. Allows trafficking of small,
polar molecules, RNAs, and proteins. Typically 3000-4000 per nucleus (the
number is related to nuclear activity). Large highly complex structure (~30X
> ribosome). Structure is an 8-fold symmetrical structure organized around
a large, central aqueous channel. Size exclusion limit - molecules >40 kDa
MCB*2050 Final Exam Key Terms with
Complete Solutions
Nucleus - ✔✔Control center of the cell. Contains DNA. Largest
organelle. Responsible for 1) compartmentalizations of the cellular genome
and its activities and 2) coordination of cellular activities
Nucleoplasm - ✔✔Fluid-filled interior of the nucleus - highly organized.
Consists of >30 specialized regions ('subdomains') that participate in
specific functions
Nucleoid - ✔✔Prokaryotes possess this region where the chromosome is
located. There's less DNA, less DNA packaging and little/no RNA
processing.
Nucleolus - ✔✔Most obvious nuclear subdomain. Irregular shape, dense
and granular in appearance. Functions in producing ribosomes. Site of
ribosomal DNA (rDNA) gene transcription, RNA processing, and initial
stages of ribosomal subunit (rRNA + protein) assembly
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
Transcription factories - ✔✔Active genes (euchromatin) from different
subdomains/regions of the same chromosome extend into
interchromosomal channels to form this. This is where transcription factors
are concentrated.
Interchromosomal channel - ✔✔Regions between subdomains that
serve as barriers to prevent unwanted DNA-DNA and/or DNA/protein
interactions
Nuclear speckle - ✔✔Subdomains where mRNA splicing factors are
concentrated (where pre-mRNA processing occurs). They appear as
speckles under fluorescent microscopy. Often located in interchromosomal
channels next to transcription factors. Numerous and highly dynamic. >50
in number. Can move quickly and grow/shrink depending on the needs of
the cell
Nuclear matrix - ✔✔Insoluble fibrillar-like protein network ('mesh')
distributed throughout the nucleoplasm. Analogous to the cytoskeleton
network in the cytoplasm. Has a structural role: maintains the overall shape
of the nucleus. Serves as a scaffold - responsible for organizing nuclear
subdomains and anchoring protein factors. Very little known about its
composition and assembly/disassembly.
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
Cytoskeleton network - ✔✔Located in the cytoplasm. Analogous to the
nuclear matrix. Composed of three major filament systems: microtubules,
actin microfilaments, and intermediate filaments.
Nuclear envelope - ✔✔Separates nuclear contents from the surrounding
cytoplasm. Acts as a barrier - requires the regulated passage of molecules
(e.g. RNA and proteins) between the nucleus and cytoplasm. Establishes
the unique composition of the nucleus and spatially regulates gene
expression. Provides the structural framework for the nucleus. Sandwiched
between the inner and outer membrane. Composed of three main parts:
nuclear membranes, nuclear lamina, nuclear pore complex.
Inner nuclear membrane - ✔✔Unique protein composition. One of the
concentric membranes (phospholipid bilayers). Directly beside the nuclear
envelope. Joins other membrane at nuclear pore complex. Sits in parallel to
the other membrane. Serves as a barrier to the passage of ions, solutes,
and macromolecules between the nucleoplasm and cytoplasm.
Outer nuclear membrane - ✔✔Continuous with RER. Ribosomes
attached to cytoplasmic surface of it. One of the concentric membranes
(phospholipid bilayers). Directly beside the nuclear envelope. Joins other
membrane at nuclear pore complex. Sits in parallel to the other membrane.
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
Serves as a barrier to the passage of ions, solutes, and macromolecules
between the nucleoplasm and cytoplasm
Nuclear envelope lumen - ✔✔Separates the inner and outer membrane.
10-50 nm diameter. Continuous with the ER lumen.
Nuclear lamina - ✔✔Located on the inner surface of the nuclear inner
membrane. Network ('mesh') of long, filament-like proteins. Provides
mechanical support to nuclear envelope (binds to nuclear inner membrane
integral proteins). Serves as a scaffold for attachment of chromatin and
nuclear matrix to the nuclear envelope.
ABC nuclear lamins - ✔✔Evolutionary related to proteins that form
intermediate filaments in the cytoskeleton network.
Nuclear pore complex (NPC) - ✔✔Channels/doorways in the nuclear
envelope. Responsible for the regulated trafficking of all
substances between the nucleus and cytoplasm. Allows trafficking of small,
polar molecules, RNAs, and proteins. Typically 3000-4000 per nucleus (the
number is related to nuclear activity). Large highly complex structure (~30X
> ribosome). Structure is an 8-fold symmetrical structure organized around
a large, central aqueous channel. Size exclusion limit - molecules >40 kDa
