Flashcards in Comparmentalization Of Cells Deck (85):
Catalyze mostly by membrane-bound enzymes
Both require a membrane to couple the transport of H+ to the synthesis of ATP
Oxidative phosphorylation and photosynthesis
Provide increased membrane area, they also create enclosed compartments that are separate from the cytosol, thus providing the cell with functionally specialized aqueous spaces.
Intracellular membrane systems
Responsible for the import and export of specific metabolites
Membrane transport proteins
Mechanism of each organelle
>incorporating into the organelle
Contains the main genome and is the principle site of DNA and RNA synthesis.
Consists of cytosol and organelles suspended on it.
Site of protein synthesis and degradation, also performs most of the cells intermediary metabolism - the many reactions by which some small molecules are degraded and others are synthesized to provide building blocks for macromolecules.
Has many ribosomes bound to its cytosolic surface, they are engaged in synthesis of both soluble and integral membrane proteins, most of which are destined either for secretion to the cell exterior or for other organelles.
Translocated into the ER as they are synthesized. This explains why ER membrane is unique in having ribosomes tethered to it.
Produces most of the lipid for the rest of the cell and functions as a store CA2+ ions.
Consists of organized stacks of disc like compartments. Receives lipids and proteins from the ER dispatches them to a variety of destinations, usually covalently modifying them en route.
Disc like compartments
Generate most of the ATP used by cells to drive reactions that require an input of free energy.
Mitochondria and chloroplasts
Specialized version of plastids, functions as storage of food and pigment molecules.
Contain digestive enzymes that degrade defunct intracellular organelles, as well as macromolecules and particles taken in from from outside the cell endocytosis.
Endocytosed materials must first pass through these series of organelles.
Small vesicular compartments that contain enzymes utilized in a variety of oxidative reactions.
Form during development of chloroplasts from proplastids in the green leaves of plants.
Small pre cursor organelles that are present in all immature plant cells.
Harbors all of the chloroplast's photosynthetic machinery.
Surrounded by a double membrane, remain isolated from the extensive vesicular traffic that connects the interiors of the most of the other membrane-enclosed organelles to each other and to the outside of the cell.
Membrane and plastids
Intracellular compartments in eukaryotic cells
1. Nucleus and cytosol
2. Organelles that function in the secretory and endocytosis pathways.
Direct their delivery to locations outside the cytosol.
Protein traffic between the cytosol and nucleus occurs between topologically equivalent spaces, which are in continuity in the nuclear pore complexes.
Function as selective gates that actively transport specific macromolecules and macromolecule assemblies but also follow free diffusion of small molecules.
Nuclear pore complexes
Membrane bound protein translocation directly transport specific proteins across the membrane from the cytosol into the space that is topologically distinct.
Membrane enclosed transport intermediates, pericarp like transport vesicles or larger irregularly shaped organelle, ferry proteins from one compartment to another.
Removes the finished proteins that are typically 15-60 residues long.
Used to direct proteins from the cytosol to the ER, mitochondria, chloroplasts and peroxisomes, they are also used to transport proteins from the nucleus to the cytosol and from the Golgi to the ER.
Sorting signals that direct proteins into the nucleus from the cytosol.
Direct newly synthesized degrading enzymes that to the lysosomes
Proteins for initial transfer to the ER.
Signal sequence at N terminus
Recognized as ER residents
Four amino acids at their c terminus
Proteins destined for mitochondria
Positively charged amino acids alternate with hydrophobic ones.
Sufficient for protein targeting
Proteins destined for peroxisomes
Signal peptide of three characteristic amino acid on their C terminus
Guides proteins to their appropriate destination, sorting signals are recognized by this.
Passed from one parent cell to progeny cell in a form of the organelle itself.
Encloses the DNA and defines compartment
Specific proteins that acts as a binding site for chromatin and for protein mesh work or nuclear lamina.
Inner nuclear membrane
Provides structural support for nuclear membrane
Studded with ribosomes engaged in protein synthesis
Outer nuclear membrane
Space between inner and outer nuclear membrane
Occurs continuously between cytosol and nucleus
Small water soluble molecules can passively diffuse through this
Selectivity of the nuclear process resides in this, present only in the nuclear proteins
Nuclear localization signals
Nuclear localization signals must be recognized by this
Nuclear import receptors
Serve as a binding sites for the import receptors
These receptors bind both the export signal and nucleoporins to guide their cargo through the pore complex to the cytosol
Nuclear export receptor
Found in both cytosol and nucleus, required both the nuclear import and export systems
Become bound to proteins that are loaded into the RNA transcription and splicing proceed.
Recognized by export receptors that guide RNA out of the nucleus through nuclear pore complexes.
Nuclear export signals
Interconnected protein subunits
Meshwork of interconnected protein subunits
Special class of intermediate filament proteins that polymerize into a two-dimensional lattice
What happens to the nuclear lamina when the nucleus disassembles during mitosis?
Double membrane enclosed organelles
Mitochondria and chloroplast
Forms intensive invaginations
Inner membrane of mitochondria
Encloses the matrix space
Part of mitochondria that is in contact with the cytosol
Outer membrane of mitochondria
Mitochondrial proteins are first fully synthesized as precursor proteins in the cytosol and then translocated into the mitochondria by this mechanism
Multi subunit protein complexes that function as a protein translocator across the outer membrane
Function across the inner membrane
TIM23 & TIM22
Mediates insertion of inner membrane proteins that are synthesized within the mitochondria
Contact sites of matrix space
Surrounded by only a single membrane, all of the proteins of this organelle must be imported.
Present in all eukaryotic cells, contain oxidative enzymes, catalase and urate oxidase
Utilizes hydrogen peroxide generated by other organelle to oxidize a variety of other substrates
Process of breaking down fatty acid molecules
Most abundant class of phospholipids in myelin
Uses up O2 and liberates CO2
Conversion of fats to sugars
A defect in importing proteins into peroxisomes, individuals that contain "empty" peroxisomes
Organized into a netlike labyrinth of branching tubules and flattened sacs throughout the cytosol
Central role in lipid and protein synthesis
Partly translocated across ER and and become embedded in it.
Fully translocated across the ER membrane and release into the ER lumen.
Water soluble proteins
Contain ER exit sites.
A cell that is abundant with smooth ER
Specialized smooth ER, sequesters Ca2+ from the cytosol by mean of Ca2+ ATPase that pumps Ca2+ ions into the lumen
Sarcomas mic reticulum
Small closed vesicles that form when ER breaks into fragments when being disrupted.
ER resident protein, catalyze sa free sulfhydryl groups on cysteines to form disulfide bonds
Protein disulfide isomerism
Can be formed in three steps: choline, two fatty acids, and glycerol phosphate